Mybatis学习记录(二)--Mybatis开发DAO方式

转载自：http://blog.csdn.net/u012706811/article/details/51156153

mybatis开发dao的方法通常用两种,一种是传统DAO的方法,一种是基于mapper代理的方法,下面学习这两种开发模式.

写dao之前应该要对SqlSession有一个更加细致的了解

一.mybatis的SqlSession使用范围

SqlSessionFactoryBuilder用于创建SqlSessionFacoty，SqlSessionFacoty一旦创建完成就不需要SqlSessionFactoryBuilder了，因为SqlSession是通过SqlSessionFactory生产，所以可以将SqlSessionFactoryBuilder当成一个工具类使用，最佳使用范围是方法范围即方法体内局部变量。

SqlSessionFactory是一个接口，接口中定义了openSession的不同重载方法，SqlSessionFactory的最佳使用范围是整个应用运行期间，一旦创建后可以重复使用，通常以单例模式管理SqlSessionFactory。

SqlSession中封装了对数据库的操作，如：查询、插入、更新、删除等。通过SqlSessionFactory创建SqlSession，而SqlSessionFactory是通过SqlSessionFactoryBuilder进行创建。
SqlSession是一个面向用户的接口，sqlSession中定义了数据库操作，默认使用DefaultSqlSession实现类。 

具体执行过程如下: 
加载数据源等配置信息Environment environment = configuration.getEnvironment();
创建数据库链接
创建事务对象创建Executor，SqlSession所有操作都是通过Executor完成 

对应源码:

<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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (ExecutorType.BATCH == executorType) {
executor = newBatchExecutor(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, transaction);
} elseif (ExecutorType.REUSE == executorType) {
executor = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ReuseExecutor(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, transaction);
} <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
executor = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> SimpleExecutor(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, transaction);
}
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (cacheEnabled) {
executor = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> CachingExecutor(executor, autoCommit);
}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li></ul>

结论得出 

每个线程都应该有它自己的SqlSession实例。SqlSession的实例不能共享使用，它也是线程不安全的。因此最佳的范围是请求或方法范围。绝对不能将SqlSession实例的引用放在一个类的静态字段或实例字段中。 

打开一个 SqlSession；使用完毕就要关闭它。通常把这个关闭操作放到 finally 块中以确保每次都能执行关闭。

二.传统DAO开发方法

传统的方法是建立dao接口定义方法,然后创建其实现类,实现dao中的方法.下面代码用的还是第一篇的例子 
无论是哪种开发方法,mapper.xml都要写的,mapper映射也都需要在SqlMapperConfig.xml中配置的

1.User.xml编写

和上一篇中的一模一样,这里为了完整的流程才贴出来的

<code class="hljs xml 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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-pi" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><?xml version="1.0" encoding="UTF-8" ?></span>
<span class="hljs-doctype" style="margin: 0px; padding: 0px; color: rgb(102, 0, 102); box-sizing: border-box;"><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd"></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--命名空间，用于隔离sql语句，后面会讲另一层非常重要的作用。--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">namespace</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"test"</span>></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--根据id查询出用户信息(查询一条数据)--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">select</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"findUserById"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">parameterType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"int"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">resultType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"com.aust.model.User"</span>></span>
SELECT * FROM user WHERE id=#{id}
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">select</span>></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--根据名称进行模糊查询(查询出多条数据)--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">select</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"findUserByName"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">parameterType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"java.lang.String"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">resultType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"com.aust.model.User"</span>></span>
SELECT * from user WHERE nickname LIKE '%${value}%'
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">select</span>></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--插入一个用户--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">insert</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"insertUser"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">parameterType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"com.aust.model.User"</span>></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">selectKey</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">keyProperty</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"id"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">resultType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"java.lang.Integer"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">order</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"AFTER"</span> ></span>
SELECT last_insert_id()
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">selectKey</span>></span>
INSERT INTO user(username,password,nickname,status) VALUE (#{username},#{password},#{nickname},#{status})
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">insert</span>></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--删除一个用户--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">delete</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"deleteUser"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">parameterType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"int"</span>></span>
DELETE FROM user WHERE id =#{id}
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">delete</span>></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--更新用户--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">update</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"updateUser"</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">parameterType</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"com.aust.model.User"</span>></span>
UPDATE user SET username=#{username},password=#{password},nickname=#{nickname} WHERE id = #{id}
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">update</span>></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span>></span></code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">13</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">14</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">15</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">16</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">17</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">18</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">19</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">20</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">21</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">22</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">23</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">24</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">25</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">26</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">27</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">28</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">29</li></ul>

2.配置mapper映射

在SqlMapperConfig,xml中配置即可

<code class="hljs xml 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-radius: 0px; word-wrap: normal; background: transparent;">  <span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--配置mappeer映射--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mappers</span>></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">resource</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"mapper/User.xml"</span>/></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mappers</span>></span></code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li></ul>

3.实现dao接口

<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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="margin: 0px; padding: 0px; box-sizing: border-box;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">interface</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">UserDao</span> {</span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//根据id查询用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> User <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserById</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//根据姓名模糊查询用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> List<User> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByName</span>(String name);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//插入一个用户,返回主键</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">insertUser</span>(User user);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//删除一个用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">deleteUser</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//更新一个用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">updateUser</span>(User user);
}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li></ul>

4.实现dao接口的实现类

<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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="margin: 0px; padding: 0px; box-sizing: border-box;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">UserDaoImp</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">implements</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">UserDao</span>{</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">private</span> SqlSessionFactory factory;

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//通过构造注入SqlSessionFactory,后期整合spring,全部交给spring管理</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">UserDaoImp</span>(SqlSessionFactory factory) {
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.factory = factory;
}

<span class="hljs-annotation" style="margin: 0px; padding: 0px; color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> User <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserById</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id) {
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//放在方法体内创建,保证线程安全</span>
SqlSession session = factory.openSession();
User user = session.selectOne(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"test.findUserById"</span>,id);
session.close();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">return</span> user;
}

<span class="hljs-annotation" style="margin: 0px; padding: 0px; color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> List<User> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByName</span>(String name) {
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//放在方法体内创建,保证线程安全</span>
SqlSession session = factory.openSession();
List<User> users = session.selectList(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"test.findUserByName"</span>,name);
session.close();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">return</span> users;
}

<span class="hljs-annotation" style="margin: 0px; padding: 0px; color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">insertUser</span>(User user) {
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//放在方法体内创建,保证线程安全</span>
SqlSession session = factory.openSession();
session.insert(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"test.insertUser"</span>,user);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//一定要提交,不然是失败</span>
session.commit();
session.close();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">return</span> user.getId();
}

<span class="hljs-annotation" style="margin: 0px; padding: 0px; color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">deleteUser</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id) {
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//放在方法体内创建,保证线程安全</span>
SqlSession session = factory.openSession();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = session.delete(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"test.deleteUser"</span>,id);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//一定要提交,不然是失败</span>
session.commit();
session.close();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">return</span> i><span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
}

<span class="hljs-annotation" style="margin: 0px; padding: 0px; color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">updateUser</span>(User user) {
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//放在方法体内创建,保证线程安全</span>
SqlSession session = factory.openSession();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = session.delete(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"test.updateUser"</span>,user);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//一定要提交,不然是失败</span>
session.commit();
session.close();
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">return</span> i><span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
}
}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">13</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">14</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">15</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">16</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">17</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">18</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">19</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">20</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">21</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">22</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">23</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">24</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">25</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">26</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">27</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">28</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">29</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">30</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">31</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">32</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">33</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">34</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">35</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">36</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">37</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">38</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">39</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">40</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">41</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">42</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">43</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">44</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">45</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">46</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">47</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">48</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">49</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">50</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">51</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">52</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">53</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">54</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">55</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">56</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">57</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">58</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">59</li></ul>

5.写junit测试

<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-radius: 0px; word-wrap: normal; background: transparent;">    SqlSessionFactory factory  = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;

@Before
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">init</span>(){
InputStream <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span> = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span> = Resources.getResourceAsStream(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"SqlMapperConfig.xml"</span>);
} <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e) {
e.printStackTrace();
}
factory = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> SqlSessionFactoryBuilder().build(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span>);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试取出单个</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByIdTest</span>(){
UserDaoImp daoImp = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> UserDaoImp(factory);
User user = daoImp.findUserById(<span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(user);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试取出多个</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByNameTest</span>(){
UserDaoImp daoImp = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> UserDaoImp(factory);
List<User> users = daoImp.findUserByName(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"张"</span>);
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(users);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试插入数据</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">insertUserTest</span>(){
UserDaoImp daoImp = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> UserDaoImp(factory);
User u = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> User();
u.setUsername(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"niuli1"</span>);
u.setPassword(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"123456"</span>);
u.setNickname(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"牛李"</span>);
u.setStatus(<span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> index = daoImp.insertUser(u);
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(index);

}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">13</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">14</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">15</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">16</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">17</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">18</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">19</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">20</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">21</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">22</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">23</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">24</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">25</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">26</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">27</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">28</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">29</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">30</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">31</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">32</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">33</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">34</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">35</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">36</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">37</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">38</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">39</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">40</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">41</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">42</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">43</li></ul>

以上五步就是传统DAO开发方法

6.原始DAO开发方法存在的问题

Dao方法体存在重复代码：通过SqlSessionFactory创建SqlSession，调用SqlSession的数据库操作方法
调用sqlSession的数据库操作方法需要指定statement的id，这里存在硬编码，不得于开发维护。

二.基于Mapper代理接口

1.实现原理

Mapper接口开发方法只需要程序员编写Mapper接口（相当于Dao接口），由Mybatis框架根据接口定义创建接口的动态代理对象，代理对象的方法体同上边Dao接口实现类方法。换句话说也就是不用程序员自己编写DAO接口的实现类了

2.UserMapper接口

接口定义有如下特点： 

1、Mapper接口方法名和Mapper.xml中定义的statement的id相同 

2、Mapper接口方法的输入参数类型和mapper.xml中定义的statement的parameterType的类型相同 

3、Mapper接口方法的输出参数类型和mapper.xml中定义的statement的resultType的类型相同

<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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">interface</span> UserMapper {

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//根据id查询用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> User <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserById</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//根据姓名模糊查询用户</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> List<User> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByName</span>(String name);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//插入一个用户,返回受影响的行数</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">insertUser</span>(User user);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//删除一个用户,返回受影响的行数</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">deleteUser</span>(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> id);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//更新一个用户,返回受影响的行数</span>
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">updateUser</span>(User user);
}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">13</li></ul>

3.UserMapper.xml

Mapper接口开发需要遵循以下规范： 

1、Mapper.xml文件中的namespace与mapper接口的类路径相同。

<code class="hljs xml 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-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-pi" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><?xml version="1.0" encoding="UTF-8" ?></span>
<span class="hljs-doctype" style="margin: 0px; padding: 0px; color: rgb(102, 0, 102); box-sizing: border-box;"><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd"></span>
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--命名空间，基于Mapper代理的话要是Mapper代理类路径。--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">namespace</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"com.aust.dao.UserMapper"</span>></span>

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--其余内容和上面的User.xml一样--></span>

<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span>></span></code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li></ul>

4.配置Mapper映射

无论哪种方式都需要配置映射

<code class="hljs xml 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-radius: 0px; word-wrap: normal; background: transparent;">  <span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;"><!--配置mappeer映射--></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mappers</span>></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mapper</span> <span class="hljs-attribute" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(102, 0, 102);">resource</span>=<span class="hljs-value" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 136, 0);">"mapper/UserMapper.xml"</span>/></span>
<span class="hljs-tag" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(0, 0, 136);">mappers</span>></span></code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li></ul>

5.写junit测试

<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-radius: 0px; word-wrap: normal; background: transparent;">  @Before
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">init</span>(){
InputStream <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span> = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span> = Resources.getResourceAsStream(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"SqlMapperConfig.xml"</span>);
} <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e) {
e.printStackTrace();
}
factory = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> SqlSessionFactoryBuilder().build(<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">is</span>);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试取出单个</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByIdTest</span>(){
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//获取sqlsession</span>
SqlSession session = factory.openSession();
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//创建mapper代理</span>
UserMapper mapper = session.getMapper(UserMapper.class);
<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//利用mapper代理查询</span>
User u = mapper.findUserById(<span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);
session.close();
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(u);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试取出多个</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">findUserByNameTest</span>(){
SqlSession session = factory.openSession();
UserMapper mapper = session.getMapper(UserMapper.class);
List<User> users = mapper.findUserByName(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"张"</span>);
session.close();
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(users);
}

<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//测试插入数据</span>
@Test
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="margin: 0px; padding: 0px; box-sizing: border-box;">insertUserTest</span>(){
SqlSession session = factory.openSession();
UserMapper mapper = session.getMapper(UserMapper.class);
User u = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">new</span> User();
u.setUsername(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"niuli1"</span>);
u.setPassword(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"123456"</span>);
u.setNickname(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(0, 136, 0); box-sizing: border-box;">"牛李"</span>);
u.setStatus(<span class="hljs-number" style="margin: 0px; padding: 0px; color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);
<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">int</span> index = mapper.insertUser(u);
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(index);<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//获取受影响的行数</span>
System.<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 136); box-sizing: border-box;">out</span>.println(u.getId());<span class="hljs-comment" style="margin: 0px; padding: 0px; color: rgb(136, 0, 0); box-sizing: border-box;">//获取返回的自增主键</span>

}</code><ul class="pre-numbering" style="margin: 0px; padding: 6px 0px 40px; box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; 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="margin: 0px; padding: 0px 5px; box-sizing: border-box;">1</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">2</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">3</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">4</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">5</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">6</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">7</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">8</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">9</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">10</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">11</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">12</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">13</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">14</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">15</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">16</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">17</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">18</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">19</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">20</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">21</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">22</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">23</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">24</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">25</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">26</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">27</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">28</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">29</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">30</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">31</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">32</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">33</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">34</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">35</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">36</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">37</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">38</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">39</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">40</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">41</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">42</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">43</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">44</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">45</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">46</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">47</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">48</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">49</li><li style="margin: 0px; padding: 0px 5px; box-sizing: border-box;">50</li></ul>

6.总结

selectOne和selectList动态代理对象调用sqlSession.selectOne()和sqlSession.selectList()是根据mapper接口方法的返回值决定，如果返回list则调用selectList方法，如果返回单个对象则调用selectOne方法。
mybatis官方推荐使用mapper代理方法开发mapper接口，程序员不用编写mapper接口实现类。
可以发现使用Mapper代理的方式,在Mapper接口中输入参数必须只能是一个,但是怎么才能满足多样查询呢?mybatis建议输入参数可以使用pojo包装对象或map对象，保证dao的通用性.