1 package cn.mybatis.po;2 3 public class UserPoJo extends User{4     private User user;5 6     public void setUser(User user) {7         this.user = user;8     }9
10     public User getUser() {
11         return user;
12     }
13 }复制代码

 1 package cn.mybatis.po;2 3 public class UserVo {4     private UserPoJo userPoJo;5 6     public UserPoJo getUserPoJo() {7         return userPoJo;8     }9
10     public void setUserPoJo(UserPoJo userPoJo) {
11         this.userPoJo = userPoJo;
12     }
13 }复制代码

    //测试包装类型的查询public List<UserPoJo> findUserList(UserVo userVo) throws Exception;复制代码

 1     @Test2     public void testFindUserList() throws Exception {3         SqlSession sqlSession = sqlSessionFactory.openSession();4         UserMapper userMapper = sqlSession.getMapper(UserMapper.class);5 6         UserPoJo userPoJo = new UserPoJo();7         UserVo userVo = new UserVo();8         userPoJo.setSex("男");9         userPoJo.setUsername("u");
10         userVo.setUserPoJo(userPoJo);
11
12         List<UserPoJo> userPoJoList = userMapper.findUserList(userVo);
13
14         System.out.println(userPoJoList);
15     }复制代码

SELECT COUNT(*) FROM t_userSELECT username FROM t_user WHERE id = 2复制代码

 1 <?xml version="1.0" encoding="UTF-8" ?>2 <!DOCTYPE mapper3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">5 <mapper namespace="cn.mybatis.mapper.UserMapper">6 7     <!--定义resultMap8         type:resultMap最终映射的Java对象类型9         id:对resultMap的标识
10     -->
11     <resultMap id="userResultMap" type="user">
12         <!--id:标识查询结果集中的唯一标识-->
13         <id column="_id" property="id"></id>
14         <!--result:标识查询结果集中其他列的标识-->
15         <result column="_username" property="username"></result>
16         <result column="_password" property="password"></result>
17         <result column="_sex" property="sex"></result>
18         <result column="_address" property="address"></result>
19     </resultMap>
20
21     <select id="findUserById_resultMap" parameterType="int" resultMap="userResultMap">
22         SELECT id _id, username _username, PASSWORD _password, address _address, sex _sex FROM t_user WHERE id = #{id}
23     </select>
24 </mapper>复制代码

    //测试resultMappublic User findUserById_resultMap(int id) throws Exception;复制代码

1     @Test
2     public void testFindUserById_resultMap() throws Exception {
3         SqlSession sqlSession = sqlSessionFactory.openSession();
4         UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
5
6         User user = userMapper.findUserById_resultMap(2);
7
8         System.out.println(user);
9     }复制代码

    <select id="findUserList" parameterType="cn.mybatis.po.UserVo" resultType="cn.mybatis.po.UserPoJo">SELECT * FROM t_user<where><if test="userPoJo != null"><if test="userPoJo.sex != null and userPoJo.sex != ''">AND sex = #{userPoJo.sex}</if><if test="userPoJo.username != null and userPoJo.username != ''">AND username LIKE '%${userPoJo.username}%'</if></if></where></select>复制代码

 1     <!--定义Sql片段-->2     <sql id="query_user_info">3         <if test="userPoJo != null">4             <if test="userPoJo.sex != null and userPoJo.sex != ''">5                 AND sex = #{userPoJo.sex}6             </if>7             <if test="userPoJo.username != null and userPoJo.username != ''">8                 AND username LIKE '%${userPoJo.username}%'9             </if>
10         </if>
11     </sql>复制代码

1     <select id="findUserList" parameterType="cn.mybatis.po.UserVo" resultType="cn.mybatis.po.UserPoJo">
2         SELECT * FROM t_user
3         <where>
4             <include refid="query_user_info"></include>
5         </where>
6     </select>复制代码

    <sql id="query_ids"><if test="ids != null"><!--SELECT * FROM t_user WHERE 1=1 AND (id = 1 OR id =2 OR id = 3)cilleation: 指定的是输入参数集合的属性名item:每次遍历的名称open:开始遍历时拼接串close:结束遍历时候拼接的串separator:遍历的两个对象中间需要拼接的串--><foreach collection="ids" item="item_id" open="AND (" close=")" separator=" OR ">id=#{item_id}</foreach></if></sql>复制代码

    <select id="findUserByIds" parameterType="userVo" resultType="userPoJo">SELECT * FROM t_user<where><include refid="query_ids"></include></where></select>复制代码