Java SSM框架之MyBatis3（二）——Mapper代理的开发方式

Mapper代理的开发规范

1、 mapper接口的全限定名要和mapper映射文件的namespace值一致。

2、 mapper接口的方法名称要和mapper映射文件的statement的id一致。

3、 mapper接口的方法参数类型要和mapper映射文件的statement的parameterType的值一致，而且它的参数是一个。

4、 mapper接口的方法返回值类型要和mapper映射文件的statement的resultType的值一致。

代码实战

1.搭建如下工程



2.mapper接口——interface UserMapper

package com.mf.mybatis.mapper;

import java.util.List;

import com.mf.mybatis.po.User;
import com.mf.mybatis.po.UserQueryVO;

public interface UserMapper {

public User findUserById(int id) throws Exception;

public void insertUser(User user) throws Exception;

public List<User> findUserList(UserQueryVO vo);

public int findUserCount(UserQueryVO vo);

public User findUserRstMap(int id);
}

3.mapper映射文件——SqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>

<properties resource="db.properties">
<property name="db.username" value="123" />
</properties>

<typeAliases>
<typeAlias type="com.mf.mybatis.po.User" alias="user"/>
<package name="com.mf.mybatis.po" />
</typeAliases>

<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${db.driver}" />
<property name="url" value="${db.url}" />
<property name="username" value="${db.username}" />
<property name="password" value="${db.password}" />
</dataSource>
</environment>
</environments>

<mappers>
<!--<mapper resource="mapper/UserMapper.xml" /> -->
<package name="com.mf.mybatis.mapper" />
</mappers>

</configuration>

4.Db.properties

db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8
db.username=root
db.password=root

5.log4j.properties

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

6.UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mf.mybatis.mapper.UserMapper">

<select id="findUserById" parameterType="int" resultType="User">
SELECT * FROM USER WHERE id =#{id}
</select>

<insert id="insertUser" parameterType="com.mf.mybatis.po.User">
<selectKey keyProperty="id" resultType="int" order="AFTER">
SELECT LAST_INSERT_ID()
</selectKey>
INSERT INTO USER(username,birthday,sex,address) VALUES(#{username},#{birthday},#{sex},#{address})
</insert>

<sql id="whereClause">
<if test="user != null">
<if test="user.username != null and user.username != ''">
AND username LIKE '%${user.username}%'
</if>
<if test="user.sex != null and user.sex != ''">
AND sex = #{user.sex}
</if>
</if>

<if test="idList != null">
AND id IN
<foreach collection="idList" item="id" open="(" close=")" separator=",">
#{id}
</foreach>
</if>
</sql>

<select id="findUserList" parameterType="com.mf.mybatis.po.UserQueryVO"    resultType="user">
SELECT * FROM user
<where>
<include refid="whereClause" />
</where>
</select>

<select id="findUserCount" parameterType="com.mf.mybatis.po.UserQueryVO" resultType="int">
SELECT count(*) FROM user
<where>
<include refid="whereClause" />
</where>
</select>

<resultMap type="user" id="UserRstMap">
<id column="id_" property="id" />
<result column="username_" property="username" />
<result column="sex_" property="sex" />
</resultMap>

<select id="findUserRstMap" parameterType="int" resultMap="UserRstMap">
Select id id_,username username_,sex sex_ from user where id = #{id}
</select>
</mapper>

7.UserQueryVO.java

package com.mf.mybatis.po;

import java.util.List;

public class UserQueryVO {

private User user;

private List<Integer> idList;

public List<Integer> getIdList() {
return idList;
}

public void setIdList(List<Integer> idList) {
this.idList = idList;
}

public User getUser() {
return user;
}

public void setUser(User user) {
this.user = user;
}
}

8.UserMapperTest.java

package com.mf.mybatis.mapper;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import com.mf.mybatis.po.User;
import com.mf.mybatis.po.UserQueryVO;

public class UserMapperTest {

private SqlSessionFactory sqlSessionFactory;

@Before
public void setUp() throws Exception {
String resource = "SqlMapConfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}

@Test
public void testFindUserById() throws Exception {

SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
User user = mapper.findUserById(1);
System.out.println(user);
sqlSession.close();

}

@Test
public void testInsertUser() throws Exception {

SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
User user = new User();
user.setUsername("sgz");
user.setAddress("北京");
mapper.insertUser(user);
System.out.println(user.getId());
sqlSession.commit();
sqlSession.close();

}

@Test
public void testFindUserList() throws Exception {

SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
UserQueryVO vo = new UserQueryVO();
// User user= new User();
// user.setUsername("沐风");
// user.setSex("1");
// vo.setUser(user);
List<Integer> idList = new ArrayList<>();
idList.add(1);
idList.add(2);
idList.add(10);
vo.setIdList(idList);

List<User> list = mapper.findUserList(vo);
int count = mapper.findUserCount(vo);

System.out.println(list);
System.out.println(count);
sqlSession.close();
}

@Test
public void testFindUserRstMap() throws Exception {

SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);

User user = mapper.findUserRstMap(1);
System.out.println(user);
sqlSession.close();
}

}