Android快速开发--使用ORMLite操作数据库

OrmLite是一个数据库操作辅助的开源框架，主要面向Java语言。在Android面向数据库开发中，是一个比较流行的开源框架，方便操作而且功能强大，今天来学习一下，最近的项目中也有所涉及，写个博客来记一下吧，感谢大神团队贡献如此实用的开源框架，这里是OrmLite的官方网址：http://ormlite.com/

准备工作–创建数据库及数据表

ORMlite通过Java注解的方式来建立起与数据库的映射关系，在这里我们以一个实例来进行说明，如我们现在想要建立一个简单的数据库test.db并创建一张表person来记录一个人的名字，年龄，住址等等。

创建Bean类

首先，建立我们的Bean类Person，并通过注解的方式与数据库联系起来

<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;"><span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@DatabaseTable</span>(tableName = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"person"</span>)
<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);">Person</span> {</span>

<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@DatabaseField</span>(generatedId=<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;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@DatabaseField</span>(columnName=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String name;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@DatabaseField</span>(columnName=<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;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> age;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@DatabaseField</span>(columnName=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"address"</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String address;
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> the id
*/</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;">int</span> <span class="hljs-title" style="box-sizing: border-box;">getId</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> id;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> id the id to set
*/</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;">setId</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.id = id;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> the name
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> String <span class="hljs-title" style="box-sizing: border-box;">getName</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> name;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> name the name to set
*/</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;">setName</span>(String name) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.name = name;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> the age
*/</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;">int</span> <span class="hljs-title" style="box-sizing: border-box;">getAge</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> age;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> age the age to set
*/</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: b
4000
order-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">setAge</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> age) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.age = age;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> the address
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> String <span class="hljs-title" style="box-sizing: border-box;">getAddress</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> address;
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> address the address to set
*/</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;">setAddress</span>(String address) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.address = address;
}

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><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></ul>

在这里我们创建了Bean类，并与数据库建立了联系，有两件事是我们需要做的 

1.需要在@DatabaseTable注解中填入表名 

2.在@DatabaseField(columnName=”“)填入字段名，设置字段的属性等等

字段属性说明

ORMLite为我们提供了全面的字段属性的支持，下面我们来具体看一下吧：
cloumnName:指定字段名,不指定则变量名作为字段名
canBeNull:是否可以为null
dataType:指定字段的类型
foreign 指定这个字段的对象是一个外键,外键值是这个对象的id
foreignAutoCreate 外键不存在时是否自动添加到外间表中
foreignAutoRefresh 外键值,自动刷新
foreignColumnName外键字段指定的外键表中的哪个字段
generatedId:指定字段为自增长的id,不能id,generatedIdSequence通用
id:指定字段为id
index:索引
persisted:指定是否持久化此变量,默认true
throwIfNull,如果空值抛出异常
useGetSet:指定ormlite访问变量使用set,get方法默认使用的是反射机制直接访问变量
unique:字段值唯一
uniqueIndex 唯一索引
uniqueCombo整列的值唯一

创建数据库

与Android中的数据库创建相似，使用OrmLite创建数据库需要我们创建一个SqlOpenHelper继承OrmLiteSqliteOpenHelper，在OrmLiteSqliteOpenHelper也有两个重要方法，分别是onCreate和onUpgrade，负责数据库创建以及升级时的操作

<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;"><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);">MySqlOpenHelper</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);">OrmLiteSqliteOpenHelper</span> {</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Dao<Person, Integer> mPersonDao;

<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;">MySqlOpenHelper</span>(Context context) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"test"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</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;">// TODO Auto-generated constructor stub</span>
}

<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 arg0, ConnectionSource arg1) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// TODO Auto-generated method stub</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//创建数据表</span>
TableUtils.createTableIfNotExists(arg1, Person.class);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (java.sql.SQLException e) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// TODO Auto-generated catch block</span>
e.printStackTrace();
}
}

<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 arg0, ConnectionSource arg1, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> arg2,
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> arg3) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// TODO Auto-generated method stub</span>

}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Dao<Person, Integer> <span class="hljs-title" style="box-sizing: border-box;">getPersonDao</span>() <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> java.sql.SQLException {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mPersonDao == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
mPersonDao = getDao(Person.class);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> mPersonDao;
}

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><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
10cda
: 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></ul>

Dao是一个很重要的类， 这些Dao对象用于以后的数据库操作，其包含两个泛型,第一个泛型表DAO操作的类，第二个是标记数据表的ID。

数据库操作

创建了我们自己的数据库之后就可以来，对数据库操作了，接下来我们看看如何进行数据库的增删查改

插入操作

这些方法使用起来都比较简单，我们只需将自己的Bean传入到下列方法中即可
create:插入一条数据
createIfNotExists:如果不存在则插入
createOrUpdate:如果存在则更新

查询操作

OrmLite为我提供了一系列的查询操作，方法很多，而且很多都是只看方法名就可以知道的，这里就不逐一介绍了，在这里介绍一下如何使用QueryBuilder进行复杂查找。
首先调用personDao.queryBuilder();获得该Dao下的QueryBuilder对象，
接下来设置QueryBuilder的查询条件，
最后通过QueryBuilder的query方法获得List对象，

下面介绍几个常用的builder下的查询， 

1.多字段条件查询：

<code class="hljs perl has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;">QueryBuilder builder = dao.queryBuilder();
builder.where().e<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">q("字段名1","条件1")</span>.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">and</span>.e<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">q(""字段名2","条件2")</span>;
builder.query(); </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><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>

2.查询并按顺序输出

<code class="hljs erlang has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;"><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">QueryBuilder</span><<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">Person</span>, <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">Integer</span>> builder = dao.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">query</span><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">Builder</span>();
builder.order<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">By</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"字段名"</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">true</span>);
builder.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">query</span>();</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><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>

orderBy的方法第一参数表示按那个字段进行排序，第二个参数表示是否为升序。

3.分页查询

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;">QueryBuilder<Person, Integer> builder = dao<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.queryBuilder</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
builder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.offset</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;//表示查询的起始位置</span>
builder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.limit</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;//表示总共获取的对象数量</span>
builder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.query</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; background-color: rgb(238, 238, 238); 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;"><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></ul>

删除和更改操作

与查询操作类似，ORMLite同样为我们提供了一系列的方法，同时也提供了复杂删除，复杂更改的DeleteBuilder和UpdateBuilder，其用法与QueryBuilder相似，就不详细介绍了。

将数据库放置在SD卡

Android创建数据库默认的存储路径是在/data/data/packagename/database 目录之下，一方面如果数据库庞大将占用系统存储空间，另一方面如果没有获得系统ROOT权限，将不能直观的看到该数据库。所以在最后介绍一下如何将数据库建立在指定的SD卡目录之下。

这个在ORMLite中并没有提供，自己来动手写一写吧。阅读一下Android的源码可以很容易发现，Android数据库存放的目录是由ContextWrapper类下的public File getDatabasePath(String name)方法决定的，那么我们只需创建自己的Context覆盖该方法即可。

<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;"><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);">DatabaseContext</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);">ContextWrapper</span> {</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> String ROOT_SDCARD = Environment
.getExternalStorageDirectory().getAbsolutePath();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String dbDir;

<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;">DatabaseContext</span>(Context base, String path) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(base);
dbDir = path;
}

<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> File <span class="hljs-title" style="box-sizing: border-box;">getDatabasePath</span>(String name) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 判断是否存在sd卡</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> sdExist = android.os.Environment.MEDIA_MOUNTED
.equals(android.os.Environment.getExternalStorageState());
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!sdExist) {<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 如果不存在,</span>
Log.e(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Database error"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SD卡不存在"</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;">null</span>;
}

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 判断目录是否存在，不存在则创建该目录</span>
File dirFile = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(dbDir);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!dirFile.exists())
dirFile.mkdirs();

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 标记数据库文件是否创建成功</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> isFileCreateSuccess = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
String dbPath = dbDir + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/"</span> + name;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 数据库路径</span>
File dbFile = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(dbPath);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 如果数据库文件不存在则创建该文件</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!dbFile.exists()) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
isFileCreateSuccess = dbFile.createNewFile();<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 创建文件</span>
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// TODO Auto-generated catch block</span>
e.printStackTrace();
}
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
isFileCreateSuccess = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 返回数据库文件对象</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (isFileCreateSuccess)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> dbFile;
<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;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;

}

<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> SQLiteDatabase <span class="hljs-title" style="box-sizing: border-box;">openOrCreateDatabase</span>(String name, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mode,
SQLiteDatabase.CursorFactory factory) {
SQLiteDatabase result = SQLiteDatabase.openOrCreateDatabase(
getDatabasePath(name), <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> result;
}

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* Android 4.0会调用此方法获取数据库。
*
*/</span>
<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> SQLiteDatabase <span class="hljs-title" style="box-sizing: border-box;">openOrCreateDatabase</span>(String name, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mode,
CursorFactory factory, DatabaseErrorHandler errorHandler) {
SQLiteDatabase result = SQLiteDatabase.openOrCreateDatabase(
getDatabasePath(name), <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> result;
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><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></ul>

之后我们在创建SQLOpenHelper时，只需传入我们自己的DatabaseContext 即可，如

<code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; 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-position: initial initial; background-repeat: initial initial;">SdCardDBHelper dbHelper = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> SdCardDBHelper(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> DatabaseContext(
MainActivity.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, path), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"person.db"</span>);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); 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;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

ORMLite相关文件下载

附上ORMLite相关jar文件以及官方文档说明：点击下载