使用 mybatis 让 entity 和 数据库字段对应

使用resultMap 构建对应关系

<?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">
<!-- namespace用于绑定dao接口的 -->
<mapper namespace="dao.UserDao">
    <resultMap type="entity.User" id="User">
        <id property="userId" column="user_id"></id>
        <result property="userName" column="user_name" />  
                <result property="email" column="email" />  
                <result property="phoneNumber" column="phone_number" />  
                <result property="roleId" column="role_id" />  
                <result property="password" column="password" />    
    </resultMap>


    <select id="getUsers" resultMap="User">
        SELECT * FROM .t_user
    </select>
    <select id="getUserById" parameterType="Integer" resultMap="User">
        SELECT * FROM  t_user where user_id = #{id}
    </select>
    
    <select id="getUsersCount" resultType="Integer">
        SELECT count(*) FROM  t_user
    </select>
</mapper>