Android数据库框架
2016-03-22 23:00
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前言
相信不少开发者跟我一样，每次都很烦恼自己写数据库，而且那些数据库语句也经常记不住。当然网上也有很多很好的数据库框架，你可以直接拿来用，但是 很多时候我们的项目，特别是一个小型的Andrond应用原本用到的数据库结构比较简单，没必要去用那些有点臃肿的框架。当然，即使你用那些框架，当你遇到问题时，你是否也得去修改它？你要修改别人的框架必须的读懂他人的设计代码。所以不管从那个角度出发，你都得掌握简单的数据库操作。那么这篇博客就从简单的数据库操作来学习Android数据库相关知识点，然后一步一步去搭建自己的简单型数据库框架，以后就再也不用担心害怕去写数据库了，直接拿自己的数据库框架用就好了。
框架功能
public long insert(Object obj)；插入数据public List findAll(Class clazz)；查询所有数据
public List findByArgs(Class clazz, String select, String[] selectArgs) ；根据指定条件查询满足条件数据
public T findById(Class clazz, int id)；根据id查询一条记录
public void deleteById(Class
创建数据库
Android系统中已经集成了Sqlite数据库，我们直接使用它就好了，同时Android系统提供了一个数据库帮助类SQLiteOpenHelper，该类是一个抽象类，所以得写一个类来继承它实现里面的方法。代码如下：MySQLiteHelper类
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MySQLiteHelper</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">SQLiteOpenHelper</span> {</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">MySQLiteHelper</span>(Context context, String name, CursorFactory factory,
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> version) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, name, factory, version);
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(SQLiteDatabase db) {
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onUpgrade</span>(SQLiteDatabase db, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> oldVersion, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> newVersion) {
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>当数据库创建时系统会调用其中的 onCreate方法，那么我们就可以来实现 onCreate 方法来创建数据库表。假设我们要创建一张 Person表，表中有 id，name，age，flag字段。那么代码如下：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MySQLiteHelper</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">SQLiteOpenHelper</span> {</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String CREATE_TABLE = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"create table Person ("</span>
+ <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id integer primary key autoincrement, "</span>
+ <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name text, "</span>
+ <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age integer, "</span>
+ <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"flag boolean)"</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">MySQLiteHelper</span>(Context context, String name, CursorFactory factory,
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> version) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, name, factory, version);
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
...
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul>由此我们的数据库帮助类就完成了，接下来是这么使用的：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String DB_NAME = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"demo.db"</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> DB_VERSION = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">oepnDB</span>(){
MySQLiteHelper helper = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> MySQLiteHelper(context, DB_NAME, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, DB_VERSION);
SQLiteDatabase db = helper.getWritableDatabase();
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>有以上代码就已经完成了一个数据库创建以及一张表的创建，是不不是感觉不是很难呢？这么看起来的确不是很难，但是我的也不得不每次去继承SQLiteOpenHelper类来实现里面的方法。关键是每次都要去写创建表语句
<code class="hljs sql has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">public static final String CREATE_TABLE = "<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">create</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> Person (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" + "</span>id <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">integer</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">primary</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">key</span> autoincrement, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" + "</span>name text, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" + "</span>age <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">integer</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" + "</span>flag boolean)<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">";</span></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>
这里表的字段只有4个，如果有一天你遇到表里的字段有10列怎么办？还继续按照上面的方法写创建表语句么？你就不嫌繁琐么？而且容易粗错。那么有没有超级简单的方法一步完成表语句的创建呢？你细想：存放在数据库中表的这些字段无非就是一个Person类中的所有成员变量，这么一来是否可以只通过Person类型直接创建表语句呢？答案是肯定的。我们通过java 的反射机制来一步一劳永逸的实现建表操作。代码如下：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 得到建表语句
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 指定类
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> sql语句
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String <span class="hljs-title" style="box-sizing: border-box;">getCreateTableSql</span>(Class<?> clazz) {
StringBuilder sb = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> StringBuilder();
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//将类名作为表名</span>
String tabName = Utils.getTableName(clazz);
sb.append(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"create table "</span>).append(tabName).append(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" (id INTEGER PRIMARY KEY AUTOINCREMENT, "</span>);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//得到类中所有属性对象数组</span>
Field[] fields = clazz.getDeclaredFields();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (Field fd : fields) {
String fieldName = fd.getName();
String fieldType = fd.getType().getName();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (fieldName.equalsIgnoreCase(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"_id"</span>) || fieldName.equalsIgnoreCase(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">continue</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
sb.append(fieldName).append(Utils.getColumnType(fieldType)).append(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">", "</span>);
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> len = sb.length();
sb.replace(len - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, len, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">")"</span>);
Log.d(TAG, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"the result is "</span> + sb.toString());
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> sb.toString();
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul>工具类代码如下：
<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">package com.xjp.databasedemo;
import android.text.TextUtils;
import java.util.Locale;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* Created by xjp on 2016/1/23.
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> DBUtils {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//得到每一列字段的数据类型</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> String <span class="hljs-title" style="box-sizing: border-box;">getColumnType</span>(String type) {
String <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"String"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" text "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"int"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" integer "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"boolean"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" boolean "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"float"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" float "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"double"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" double "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"char"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" varchar "</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (type.contains(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"long"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" long "</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span>;
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//得到表名</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> String <span class="hljs-title" style="box-sizing: border-box;">getTableName</span>(Class<?> clazz){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> clazz.getSimpleName();
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> String <span class="hljs-title" style="box-sizing: border-box;">capitalize</span>(String <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!TextUtils.isEmpty(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.substring(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>).toUpperCase(Locale.US) + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.substring(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span> == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span> ? <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span> : <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>;
}
}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li></ul>如此一来，用户创建数据库表就变的很简单了，传入Person类的类型(Person.class)作为参数，那么代码就帮你创建出了一张名字为Person的表。使用代码如下：
<code class="hljs scala has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MySqLiteHelper</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">SQLiteOpenHelper</span> {</span>
..................
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
public void onCreate(SQLiteDatabase db) {
createTable(db);
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 根据制定类名创建表
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> void createTable(SQLiteDatabase db) {
db.execSQL(getCreateTableSql(Person.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span>));
..............
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>是不是很简单！！！领导再也不用担心我不会创建数据库了。
数据库操作–插入
android提供的数据库插入操作
对数据库插入操作 SQLite提供了如下方法<code class="hljs vbnet has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">long</span> insert(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> table, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> nullColumnHack, ContentValues values)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
可以看到，第一个参数是table 表示表名，第二个参数通常用不到，传入null即可，第三个参数将数据以 ContentValues键值对的形式存储。比如我们在数据库中插入一条人Person的信息代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">public void insert(Person person){
ContentValues values = new ContentValues()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
values<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.put</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>,person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getName</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
values<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.put</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>,person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getAge</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
values<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.put</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"flag"</span>,person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getFlag</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
db<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.insert</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Person"</span>,null,values)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>其中ContentValues是以键值对的形式存储数据，上面代码中的key 分别对应数据库中的每一列的字段，vaule分别对应着该列的值。你是否发现Person类中有几个属性就得写多少行values.put（key，value）；加入它有10个字段需要保存到数据库中，你是否觉得这样很麻烦呢？觉得麻烦就对了，接下来我们利用反射来一步完成以上数据库插入操作。
数据库插入框架
数据库插入操作框架可以减轻你写代码量，让你一步完成数据库插入操作而无须关注其内部繁琐的操作。同样利用java反射来实现以上效果。代码如下：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 插入一条数据
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> obj
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> 返回-1代表插入数据库失败，否则成功
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @throws</span> IllegalAccessException
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span> <span class="hljs-title" style="box-sizing: border-box;">insert</span>(Object obj) {
Class<?> modeClass = obj.getClass();
Field[] fields = modeClass.getDeclaredFields();
ContentValues values = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ContentValues();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (Field fd : fields) {
fd.setAccessible(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
String fieldName = fd.getName();
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//剔除主键id值得保存，由于框架默认设置id为主键自动增长</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (fieldName.equalsIgnoreCase(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id"</span>) || fieldName.equalsIgnoreCase(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"_id"</span>)) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">continue</span>;
}
putValues(values, fd, obj);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> db.insert(DBUtils.getTableName(modeClass), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, values);
}
............
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* put value to ContentValues for Database
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> values ContentValues object
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> fd the Field
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> obj the value
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">putValues</span>(ContentValues values, Field fd, Object obj) {
Class<?> clazz = values.getClass();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
Object[] parameters = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Object[]{fd.getName(), fd.get(obj)};
Class<?>[] parameterTypes = getParameterTypes(fd, fd.get(obj), parameters);
Method method = clazz.getDeclaredMethod(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"put"</span>, parameterTypes);
method.setAccessible(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
method.invoke(values, parameters);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (NoSuchMethodException e) {
e.printStackTrace();
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (InvocationTargetException e) {
e.printStackTrace();
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IllegalAccessException e) {
e.printStackTrace();
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li></ul>有以上框架之后，我们现在来向数据库插入一条数据代码如下：
<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">Person person = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Person(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Tom"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">18</span>,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>); DBManager.insert(person);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
哇！如此简单，一行代码解决繁琐的插入操作。我们只需要传入Person对象的实例作为参数即可完成数据库插入操作。再也不用去构建什么ContentVaules键值对了。
数据库操作–查询
android提供的数据库查询
android 的sqlite数据库提供的查询语句有rawQuery()方法。该方法的定义如下：<code class="hljs vbnet has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Cursor rawQuery(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> sql, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[] selectionArgs)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
其中第一个参数是sql字符串，第二个参数是用于替换SQL语句中占位符（?）的字符串数组。返回结果存放在Cursor对象当中，我们只要循环一一取出数据即可。当然我们平时不怎么用这个方法，因为需要记住很多数据库查询语句的规则等。Android给开发者封装了另外一个数据库查询方法，即SQLiteDatabase中的query()方法。该方法的定义如下：
<code class="hljs vbnet has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Cursor query(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> table, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[] columns, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> selection, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[] selectionArgs, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> groupBy, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> having, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> orderBy)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>
其中，
第一个参数是需要查询数据的表名称；
第二个参数指查询表中的那几列字段，如果不指定则默认查询所有列；
第三个参数是sql语句，表示查询条件；
第四个参数是用于替换第三个参数sql语句中的占位符（？）数组，如果第三，四个参数不指定则默认查询所有行；
第五个参数用于指定需要去group by的列，不指定则表示不对查询结果进行group by操作。
第六个参数用于对group by之后的数据进行进一步的过滤，不指定则表示不进行过滤。
第七个参数用于指定查询结果的排序方式，不指定则表示使用默认的排序方式。
query()方法的参数是不是很多，一般人都很难记住这些参数的意思，在用的时候就很不方便，比如你要查询数据库中 age=18的人，你的代码得这么写：
<code class="hljs javascript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> Cursor cursor = db.query(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Person"</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age = ?"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[]{<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"18"</span>}, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">null</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>第三个参数是查询条件，去约束查询结果 age = 18，所以 第三个参数是“age= ？”，第四个参数用于替换第三个参数的占位符（？），因此是String的数组。查询的结果保存在Cursor中，为了拿到查询结果，我们不得不去变量里Cursor一一取出其中的数据并保存。代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">List<Person> list = new ArrayList<>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
if (cursor != null && cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.moveToFirst</span>()) {
do {
Person person = new Person()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
int id = cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getInt</span>(cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getColumnIndex</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id"</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
String name = cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getString</span>(cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getColumnIndex</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
String age = cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getString</span>(cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getColumnIndex</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
boolean flag = cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getInt</span>(cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getColumnIndex</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"flag"</span>)) == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> ? true : false<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setId</span>(id)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setName</span>(name)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setAge</span>(age)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setFlag</span>(flag)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
list<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.add</span>(person)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
} while (cursor<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.moveToNext</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>为了取得Cursor中的查询结果，我们写了如此多的繁琐的代码，如果此时有一个新的Student类，那么你是否又要去修改这个查询方法呢？如此看来该查询方法和取得结果是不是没有通用性，很不方便使用。对于讨厌敲重复代码的程序员来说这样很麻烦，用的不爽，那么有没有一种方法直接将查询结果转换成我需要的类的集合呢？这里我们又要用到自己写的查询框架了，利用该框架一行代码即可搞定所有。
数据库查询框架
1.查询数据库中所有数据<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 查询数据库中所有的数据
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> <T> 以 List的形式返回数据库中所有数据
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> 返回list集合
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @throws</span> IllegalAccessException
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @throws</span> InstantiationException
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @throws</span> NoSuchMethodException
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @throws</span> InvocationTargetException
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <T> List<T> <span class="hljs-title" style="box-sizing: border-box;">findAll</span>(Class<T> clazz) {
Cursor cursor = db.query(clazz.getSimpleName(), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> getEntity(cursor, clazz);
}
.....................
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 从数据库得到实体类
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> cursor
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> <T>
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span>
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <T> List<T> <span class="hljs-title" style="box-sizing: border-box;">getEntity</span>(Cursor cursor, Class<T> clazz) {
List<T> list = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ArrayList<>();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (cursor != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span> && cursor.moveToFirst()) {
do {
Field[] fields = clazz.getDeclaredFields();
T modeClass = clazz.newInstance();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (Field field : fields) {
Class<?> cursorClass = cursor.getClass();
String columnMethodName = getColumnMethodName(field.getType());
Method cursorMethod = cursorClass.getMethod(columnMethodName, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>.class);
Object value = cursorMethod.invoke(cursor, cursor.getColumnIndex(field.getName()));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (field.getType() == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span>.class || field.getType() == Boolean.class) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"0"</span>.equals(String.valueOf(value))) {
value = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>.equals(String.valueOf(value))) {
value = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
}
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (field.getType() == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>.class || field.getType() == Character.class) {
value = ((String) value).charAt(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (field.getType() == Date.class) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span> date = (Long) value;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (date <= <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
value = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
value = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Date(date);
}
}
String methodName = makeSetterMethodName(field);
Method method = clazz.getDeclaredMethod(methodName, field.getType());
method.invoke(modeClass, value);
}
list.add(modeClass);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (cursor.moveToNext());
}
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e) {
e.printStackTrace();
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">finally</span> {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (cursor != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
cursor.close();
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> list;
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li></ul>查询所有数据并且自动保存在List中返回，无须用户去将Cursor解析成对象封装。简单易用，自需要一个方法一个参数即可。调用代码如下：
<code class="hljs php has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">List</span><Person> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">list</span> = dbManager.findAll(Person.class);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
超级简单啊！
2.查询指定条件的数据
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 根据指定条件返回满足条件的记录
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 类
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> select 条件语句 ：（"id>？"）
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> selectArgs 条件(new String[]{"0"}) 查询id=0的记录
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> <T> 类型
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> 返回满足条件的list集合
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <T> List<T> <span class="hljs-title" style="box-sizing: border-box;">findByArgs</span>(Class<T> clazz, String select, String[] selectArgs) {
Cursor cursor = db.query(clazz.getSimpleName(), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, select, selectArgs, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> getEntity(cursor, clazz);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>3.根据指定id查询一条数据
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 通过id查找制定数据
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 指定类
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> id 条件id
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> <T> 类型
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> 返回满足条件的对象
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <T> T <span class="hljs-title" style="box-sizing: border-box;">findById</span>(Class<T> clazz, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id) {
Cursor cursor = db.query(clazz.getSimpleName(), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id="</span> + id, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
List<T> list = getEntity(cursor, clazz);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> list.get(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>用户代码调用如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> Person p = dbManager<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.findById</span>(Person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.class</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
查询id=1的数据，第一个参数为Person类型，第二个参数为id值，查询结果直接保存在Person对象p里。
以上就是自己封装的数据库查询操作，简单易用，无须记住quary（）方法中的那么多参数，也无须自己去一个个解析Cursor数据并保存。该方法一步到位，直接返回Person类型的list集合。
注释：其中用到的一些方法我暂时没有贴出来，文章最后我会把例子和代码都贴出来。
数据库删除操作
android提供的删除
android系统提供了sqlite数据库删除方法 delete()，其定义如下：<code class="hljs vbscript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">int</span> delete(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> table, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> whereClause, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[] whereArgs)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
其中，第一个参数表示表名，第二个参数是条件SQL语句，第三个参数是替换第二个参数中的占位符（？）。假如我要删除Person表中的age=18的数据，则代码调用如下：
<code class="hljs javascript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">db.delete(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Person"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age = ?"</span>,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[]{<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"18"</span>});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
数据库删除框架
删除这一块比较简单，我直接贴出代码来<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 删除记录一条记录
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 需要删除的类名
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> id 需要删除的 id索引
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">deleteById</span>(Class<?> clazz, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span> id) {
db.delete(DBUtils.getTableName(clazz), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id="</span> + id, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>用户调用如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">dbManager<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.deleteById</span>(Person<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.class</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
第一个 参数是Person类的类型，第二个参数是被删除数据的id。是不是很简单呢？它的实现如下：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 删除记录一条记录
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 需要删除的类名
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> id 需要删除的 id索引
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">deleteById</span>(Class<?> clazz, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span> id) {
db.delete(DBUtils.getTableName(clazz), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id="</span> + id, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>
数据库更新操作
android提供的更新操作
在android的sqlite中提供了update（）方法来更新数据操作，其定义如下：<code class="hljs vbscript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">int</span> update(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> table, ContentValues values, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span> whereClause, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[] whereArgs)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
update()方法接收四个参数，第一个参数是表名，第二个参数是一个封装了待修改数据的ContentValues对象，第三和第四个参数用于指定修改哪些行，对应了SQL语句中的where部分。
比如我要修改id=1的Person人的年龄age改成20，那么代码实现如下：
<code class="hljs javascript has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> ContentValues values = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ContentValues();
values.put(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>);
db.update(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Person"</span>,values,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id = ?"</span>,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">String</span>[]{<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>该方法也算比较简单，那么我们来看看自己写的数据库框架是怎么实现的呢？
数据库框架更新操作
<code class="hljs perl has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> ContentValues <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">values</span> = new ContentValues(); <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">values</span>.put(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">34</span>); dbManager.updateById(Person.class, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">values</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>
第一个参数为Person类的类型，第二个参数为需要更新的vaules，第三个参数是条件，更新id为1的数据。用法很简单，它的实现如下：
<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 更新一条记录
*
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> clazz 类
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> values 更新对象
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> id 更新id索引
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">updateById</span>(Class<?> clazz, ContentValues values, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">long</span> id) {
db.update(clazz.getSimpleName(), values, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"id="</span> + id, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>
总结
自此，数据库的基本操作都罗列出来了，也说明了Android提供的sqlite数据库在平时开发中的一些繁琐的地方，所以自己总结提取了一个简单型的数据库操作框架，仅仅是比较简单的操作，如果你有数据量大的操作，请出门左转利用其他多功能成熟稳定的数据库开源框架。该框架只适合数据量小，不存在表与表之间的对应关系，可以将查询结果直接转换成对象的轻量级框架。
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