1、我们先定义增删改查的接口操作，我们在接下来的运行中只需要考虑dao文件中的两个便可

package com.xie.dao;

import com.xie.pojo.User;

import java.util.List;

//等价于mapper 一定创建的是一个接口
public interface UseDao {
    //查询全部用户
    List<User> getUserList();

    //根据ID查询用户信息
    User getUserById(int id);

    //insert 一个用户
    int addUser(User user);

    //修改用户
    int updateUser(User user);

    //删除用户
    int deleteUser(int id);
}

        2、在XML文件中通过Mysql语句进行增删改查操作

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.xie.dao.UseDao">
    <!--标签和Sql语句返回值-->
    <select id="getUserList" resultType="com.xie.pojo.User">
        select * from mybatis.user1
    </select>
    <!--parameterType 需要输入的参数类型  #取数据操作和参数名字一样-->
    <select id="getUserById" resultType="com.xie.pojo.User" parameterType="int">
        select * from mybatis.user1 where id = #{id}
    </select>
    <!--insert一个用户然后插入  权限命名 全称-->
    <!--对象中的属性可以直接取出来-->
    <insert id="addUser" parameterType="com.xie.pojo.User">
        insert into mybatis.user1 (id, name, pwd) values(#{id},#{name},#{pwd});
    </insert>
    
    <!--修改用户-->
    <update id="updateUser" parameterType="com.xie.pojo.User">
        update mybatis.user1 set name = #{name}, pwd=#{pwd}  where id = #{id}
    </update>

    <!--删除一个用户-->
    <delete id="deleteUser" parameterType="int">
        delete from mybatis.user1 where id = #{id}
    </delete>
</mapper>

        3、编写测试类编程  一定在增删改查后进行提交事务操作

package com.xie.dao;

import com.xie.pojo.User;
import com.xie.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UseDaoTest {
    @Test
    public void test(){
        //第一步获得sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //方式一 执行sql 通过接口的Class对象获得相应的接口
        UseDao userDao = sqlSession.getMapper(UseDao.class);
        //快速生成对象 ctrl+alt+v
        List<User> userList = userDao.getUserList();

        for (User user : userList) {
            System.out.println(user);
        }
        //关闭
        sqlSession.close();
    }
    @Test
    public void getUserById(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UseDao mapper = sqlSession.getMapper(UseDao.class);
        User user = mapper.getUserById(1);
        System.out.println(user);

        sqlSession.close();
    }

    //提交事务
    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UseDao mapper = sqlSession.getMapper(UseDao.class);
        User user = new User(7,"chenqq","152364");
        int id = mapper.addUser(user);
        System.out.println(id);
        //提交事务
        sqlSession.commit();

        sqlSession.close();
    }

    @Test
    public void updateUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UseDao mapper = sqlSession.getMapper(UseDao.class);
        User user = new User(2,"qqchen","165985");
        int id = mapper.updateUser(user);
        System.out.println(id);
        //提交事务
        sqlSession.commit();

        sqlSession.close();
    }

    @Test
    public void deleteUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UseDao mapper = sqlSession.getMapper(UseDao.class);
        int id = mapper.deleteUser(7);
        System.out.println(id);
        //提交事务
        sqlSession.commit();

        sqlSession.close();
    }
}