實體類（注解補充getset那些）

public class User {
    private int id;
    private String name;
    private String pwd;
}

接口

public interface UserMapper {
    //獲取全部用戶
    List<User> getUserList();
    //根據ID查詢用戶
    User getUserById(int id);
    //insert一個用戶
    int addUser(User user);
    //修改用戶
    int updateUser(User user);
    //刪除用戶
    int deleteUser(int id);
}

Mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
//注意改namespace路徑
<mapper namespace="com.qi.dao.UserMapper">
    <select id="getUserList" resultType="User">
        select * from mybatis.user;
    </select>
    <select id="getUserById" parameterType="int" resultType="User">
        select * from mybatis.user where id=#{id};
    </select>
    <insert id="addUser" parameterType="User">
        insert into mybatis.user(id,name,pwd) values(#{id},#{name},#{pwd});
    </insert>
    <update id="updateUser" parameterType="User">
        update mybatis.user set name=#{name},pwd=#{pwd} where id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from mybatis.user where id=#{id};
    </delete>
</mapper>

這個寫完別忘了在資源Config.xml里補充

<mappers>
    <mapper resource="com/qi/dao/UserMapper.xml"/>
</mappers>