Mybatis Mapper动态代理开发（基础版）

àì夳堔傛蜴生んèń 2021-12-22 12:47 262阅读 0赞

1 创建项目，lib下引入Mybatis的jar包

![20190613202253534.png][]

2 引入数据库连接的jar包

![20190613202351526.png][]

3 选中所有lib下的包右键Build Path

4 编写Mybatis核心配置文件（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>
    	
    	<environments default="development">
    		<environment id="development">
    			
    			<transactionManager type="JDBC" />
    			
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.jdbc.Driver" />
    				<property name="url"
    					value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
    				<property name="username" value="root" />
    				<property name="password" value="123456" />
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
    	<mapper resource="sqlmap/User.xml"/>
    	</mappers>
    </configuration>

5 创建POJO类

public class User{
    	private Integer id;
    	private String username;
    	private String sex;
    	private Date birthday;
    	private String address;
        .......get/set方法........
    
    }

6 创建sql映射User.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.mapper.UserMapper">
    
    
    	
    
    	<select id="findUserById" parameterType="Integer" resultType="com.entity.User">
    		select * from user where id = #{v}
    	</select>
    
    
    	
    
    
    	<select id="findUserByUsername" parameterType="String"
    		resultType="com.entity.User">
    		
    		
    		select * from user where username like '%${value}%'
    	</select>
    
    	
    
    	<insert id="insertUser" parameterType="com.entity.User">
    		
    		<selectKey keyProperty="id" resultType="Integer" order="AFTER">
    			select LAST_INSERT_ID()
    		</selectKey>
    		insert into user(username,sex,birthday,address)
    		values(#{username},#{sex},#{birthday},#{address})
    	</insert>
    
    	
    	
    
    	<update id="updateUserByID" parameterType="com.entity.User">
    	update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id=#{id}
    	</update>
    
    
    	
    
    	<delete id="deleteUserById" parameterType="Integer">
    	 delete from user where id = #{value}
    	</delete>
    </mapper>

7 加载映射文件

![20190613203335406.png][]

8 编写Mapper接口类（只写接口不需要实现类（由程序生成））

package com.mapper;
    
    import com.entity.User;
    
    /**
     *
     * mapper动态代理开发
     * 只写接口不需要实现类（由程序生成）
     * 用来取代Dao
     */
    public interface UserMapper {
    	//遵循4个原则
    	//1 接口方法名 == User.xml中的id
    	//2 返回值类型 与 User.xml中的返回值一致
    	//3 方法的入参 与  User.xml中一致
    	//4 命名空间绑定此接口（User.xml中namespace写此类）
    	public User findUserById(Integer id);
    }

9 编写测试类

package com.junit;
    
    
    
    import java.io.InputStream;
    
    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.Test;
    
    import com.entity.User;
    import com.mapper.UserMapper;
    
    public class MybatisMappterTest {
    	@Test
    	public void testMapper() throws Exception {
    		String resource = "sqlMapConfig.xml";
    		InputStream inputStream = Resources.getResourceAsStream(resource);
    		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		
    		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    		User user = userMapper.findUserById(10);
    		System.out.println(user);
    	}
    
    }

[20190613202253534.png]: /images/20211220/96be5ec3b1a14cb38d8531039526336d.png
[20190613202351526.png]: /images/20211220/fa4b4f7f320c4ea98e4af45e3725e40e.png
[20190613203335406.png]: /images/20211220/bce4258aefdd49e583bde79f1f90e528.png