Mybatis之mapper代理方法

开发规范：

1. 在mapper.xml中namespace等于mapper接口地址
   
2. mapper.java接口中的方法名和mapper.xml中statement的id一致
   
3. mapper.java接口中的方法输入参数类型和mapper.xml中statement的parameterType指定的类型一致。
   
4. mapper.java接口中的方法返回值类型和mapper.xml中statement的resultType指定的类型一致
   

mapper接口：

package com.itachi.mybatis.mapper;

import java.util.List;

import com.itachi.mybatis.bean.User;

public interface UserMapper {

	public abstract User findUserById(int id) throws Exception;

	public abstract void insertUser(User user) throws Exception;

	public abstract void deleteUser(int id) throws Exception;

	public abstract void updateUser(User user) throws Exception;

	public abstract List<User> findAll() throws Exception;

}

映射文件：

<?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.itachi.mybatis.mapper.UserMapper">
	
	<select id="findUserById" parameterType="int" resultType="com.itachi.mybatis.bean.User">
		select * from user where id=#{id}
	</select>
	
	<select id="findAll" resultType="com.itachi.mybatis.bean.User">
		select * from user
	</select>
	
	<insert id="insertUser" parameterType="com.itachi.mybatis.bean.User">
		insert into user(username, birthday, sex, address) values(#{username}, #{birthday}, #{sex}, #{address})
	</insert>
	
	<update id="updateUser" parameterType="com.itachi.mybatis.bean.User">
		update user set username=#{username}, birthday=#{birthday}, sex=#{sex}, address=#{address} where id=#{id}
	</update>
	
	<delete id="deleteUser" parameterType="int">
		delete from user where id=#{id}
	</delete>
	
</mapper>

配置文件：

<?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>
	<!-- 和spring整合后，environments配置将废除 -->
	<environments default="development">
		<environment id="development">
			<!-- 使用jdbc事务管理，事务控制由mybatis -->
			<transactionManager type="JDBC"/>
			<!-- 数据库连接池，由mybatis控制 -->
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://localhost:3306/？？？"/>
				<property name="username" value="？？？"/>
				<property name="password" value="？？？"/>
			</dataSource>
		</environment>
	</environments>
	
	<mappers>
		<mapper resource="mapper/User.xml"/>
		<mapper resource="mapper/mapper.xml"/>
	</mappers>
</configuration>

测试类：

package com.itachi.mybatis.test;

import java.io.InputStream;
import java.util.Date;
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.itachi.mybatis.bean.User;
import com.itachi.mybatis.mapper.UserMapper;

public class UserMapperTest {

	private SqlSessionFactory sqlSessionFactory;

	// 此方法是在执行testFindUserById之前执行
	@Before
	public void setUp() throws Exception {
		// 创建sqlSessionFactory

		// mybatis配置文件
		String resource = "Mybatis-config.xml";
		// 得到配置文件流
		InputStream inputStream = Resources.getResourceAsStream(resource);

		// 创建会话工厂，传入mybatis的配置文件信息
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
	}

	@Test
	public void findUserByIdTest() throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		User user = userMapper.findUserById(1);
		System.out.println(user);
	}
	
	@Test
	public void insertUserTest() throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		User user = new User();
		user.setAddress("冰岛");
		user.setBirthday(new Date());
		user.setSex("1");
		user.setUsername("itachi");
		userMapper.insertUser(user);
		sqlSession.commit();
		sqlSession.close();
	}
	
	@Test
	public void updateUserTest() throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		User user = new User();
		user.setId(30);
		user.setUsername("长的萨");
		userMapper.updateUser(user);
		sqlSession.commit();
		sqlSession.close();
	}
	
	@Test
	public void deleteUserTest() throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		userMapper.deleteUser(30);
		sqlSession.commit();
		sqlSession.close();
	}
	
	@Test
	public void findAllTest() throws Exception {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		List<User> list = userMapper.findAll();
		for (User user : list) {
			System.out.println(user);
		}
	}

}

总结：与dao方法开发相比，mapper代理方法降低了硬编码带来的不便，因此推荐使用mapper代理方法