当数据库字段与实体类字段不相同时的解决方法

1.数据库

2.实体类（字段名不同）

package cn.yf.entity;

public class Admin {

    private int admin_id;
    private String admin_name;
    private String admin_password;

    public Admin() {
    }

    public Admin(int admin_id, String admin_name, String admin_password) {
        this.admin_id = admin_id;
        this.admin_name = admin_name;
        this.admin_password = admin_password;
    }

    public Admin(String admin_name, String admin_password) {
        this.admin_id = admin_id;
        this.admin_name = admin_name;
        this.admin_password = admin_password;
    }

    public int getAdmin_id() {
        return admin_id;
    }

    public void setAdmin_id(int admin_id) {
        this.admin_id = admin_id;
    }

    public String getAdmin_name() {
        return admin_name;
    }

    public void setAdmin_name(String admin_name) {
        this.admin_name = admin_name;
    }

    public String getAdmin_password() {
        return admin_password;
    }

    public void setAdmin_password(String admin_password) {
        this.admin_password = admin_password;
    }

    @Override
    public String toString() {
        return "Admin{" +
                "admin_id=" + admin_id +
                ", admin_name='" + admin_name + '\'' +
                ", admin_password='" + admin_password + '\'' +
                '}';
    }

}

3.使用ResultMap解决

<?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.yf.mapper.AdminMapper">
    <!--column：数据库字段-->
    <!--property:实体类字段-->
    <resultMap id="adminResultMap" type="cn.yf.entity.Admin">
        <id property="admin_id" column="id" ></id>
        <result property="admin_name" column="name"></result>
        <result property="admin_password" column="password"></result>
    </resultMap>
    <select id="queryAdminById" resultType="Admin" parameterType="int" resultMap="adminResultMap">
        select * from admin where id = #{admin_id}
    </select>

    <insert id="addAdmin" parameterType="Admin" >
        insert into admin(name,password) values(#{admin_name},#{admin_password})
    </insert>

    <delete id="deleteAdmin" parameterType="int">
        delete from admin where id = #{admin_id}
    </delete>

    <update id="updateAdmin" parameterType="Admin">
        update admin set name=#{admin_name},password=#{admin_password} where id=#{admin_id}
    </update>

    <select id="queryAllAdmin" resultType="Admin" resultMap="adminResultMap">
        select * from admin
    </select>

</mapper>

<resultMap id="adminResultMap" type="cn.yf.entity.Admin">
        <id property="admin_id" column="id" ></id>
        <result property="admin_name" column="name"></result>
        <result property="admin_password" column="password"></result>
</resultMap>