mybatis快速入门

Posted 2020-10-08

上面2章写了mybatis的基本操作，今天就写写mybatis的动态代理吧。

动态代理有4个基本原则：

1.userMapper.xml里面的namespace="cn.my.dao.UserDaoMapper"一定要和接口的包名+接口名一致

2.userMapper.xml里面的statementid值要和接口中的方法名一致

3.userMapper.xml里面的入参类型要和接口中方法的参数类型一致

4.userMapper.xml里面的返回类型要和接口中方法的返回类型一致

好了不废话直接上代码.

首先改造一下上一篇的代码，为了不修改user.xml，添加一个新的UserMapper.xml文件，然后修改部分代码

<?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="cn.my.dao.UserDaoMapper">
    <select id="findById" parameterType="int" resultType="cn.my.mybatis.entity.User">
        select * from user where id=#{id}
    </select>
    
    <!-- 新增映射 修改id名称为了以后封装basedao-->
    <insert id="insert" parameterType="cn.my.mybatis.entity.User">
         <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            SELECT LAST_INSERT_ID()
        </selectKey>
        INSERT INTO `user` (`username`,`birthday`,`sex`,`address`) 
        VALUES(#{username},#{birthday},#{sex},#{address})
    </insert>
   
    <!-- 修改用户 修改id名称为了以后封装basedao-->
    <update id="update" parameterType="cn.my.mybatis.entity.User">
        UPDATE `user` 
        SET
          `username` = #{username},
          `birthday` = #{birthday},
          `sex` = #{sex},
          `address` = #{address} 
        WHERE `id` = #{id} ;
    </update>
    <!-- 删除 修改id名称为了以后封装basedao -->
    <delete id="delete" parameterType="java.lang.Integer">
        delete from user where id=#{id}
    </delete>
</mapper>

 

第二步新增一个UserDaoMapper.java接口

package cn.my.dao;

import cn.my.mybatis.entity.User;

public interface UserDaoMapper {
    
    public User findById(int id);
    public void insert(User user);
    public void update(User user);
    public void delete(int id);
}

 

第三步新增一个测试类TestUserMapper.java文件

 

package cn.my.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;

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 cn.my.dao.UserDaoMapper;
import cn.my.mybatis.entity.User;

public class TestUserMapper {
    private SqlSessionFactory factory;
    @Before
    public void setUp() throws IOException{
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        factory = new SqlSessionFactoryBuilder().build(inputStream);
    }
    
    @Test  
    public void testFindById(){  
        SqlSession session = factory.openSession();
        UserDaoMapper dao = session.getMapper(UserDaoMapper.class);//获取mybatis的动态代码实现接口对象
        User user = dao.findById(10);
        session.close();  
        System.out.println(user);  
    }  
    /**
     * 新增用户
     */
    @Test  
    public void testInserUser(){  
        SqlSession session = factory.openSession();
        User user = new User();
        user.setAddress("许昌");
        user.setUsername("曹操1");
        user.setSex("男");
        user.setBirthday(new Date());
        UserDaoMapper dao = session.getMapper(UserDaoMapper.class);//获取mybatis的动态代码实现接口对象
        dao.insert(user); 
        session.commit();
        session.close();  
        System.out.println(user.getId());  
    }
    /**
     * 修改
     */
    @Test  
    public void testUpdateUser(){  
        SqlSession session = factory.openSession();
        User user = new User();
        user.setId(34);
        user.setAddress("许昌1");
        user.setUsername("曹操2");
        user.setSex("女");
        user.setBirthday(new Date());
        UserDaoMapper dao = session.getMapper(UserDaoMapper.class);//获取mybatis的动态代码实现接口对象
        dao.update(user); 
        session.commit();
        session.close();  
    }  
    /**
     * 删除
     */
    @Test  
    public void testDeleteUser(){  
        SqlSession session = factory.openSession();
        UserDaoMapper dao = session.getMapper(UserDaoMapper.class);//获取mybatis的动态代码实现接口对象
        dao.delete(34); 
        session.commit();
        session.close();  
    } 
        
        
}

 

 

 

运行结果:

查询结果：User [id=10, username=张三, sex=1, birthday=Thu Jul 10 00:00:00 CST 2014, address=北京市]

新增结果：   　　打印结果：34

 

修改结果：

 

删除结果：

 

 以上修改为动态代理就已经修改好了。

下一章写sql动态标签