java | 代理讲解 「使用 mybatis 完整案例」

这里说的是在 spring boot 中的用法。

SQL 写在 xml 文件里面。

代理需要完成 3 项

• 配置
• 编写 xml
• 编写接口代理文件

目录结构

- main
  - java
    - com.mybatis.test
      - mapper
        - UserMapper.java
  - resources
    - mapper
      - mapper.xml
    -  application.properties

配置

配置文件主要是告诉 mybatis ，xml 位于哪里。

# JDBC

Spring.datasource.url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
Spring.datasource.username=root
Spring.datasource.password=123456
Spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# Mybatis
mybatis.mapper-locations=classpath*:mapper/*.xml

UserMapper.java

UserEntity 是自定义的对象。

package com.mybatis.test.mapper;

import com.fate.backstage.entity.user.UserEntity;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper
@Repository
public interface UserMapper {

    UserEntity getUser(@Param("email") String email);
}

• mybatis | @Mapper 和 @MapperScan

mapper.xml

<?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="com.mybatis.test.mapper.UserMapper">
    <resultMap type="com.fate.backstage.entity.user.UserEntity" id="UserInfo">
        <result property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="password" column="password"/>
        <result property="nickName" column="nickName"/>
        <result property="email" column="email"/>
        <result property="token" column="token"/>
        <result property="erc20Address" column="erc20address"/>
        <result property="createTime" column="create_time"/>
    </resultMap>

    <select id="getUser" resultType="com.fate.backstage.entity.user.UserEntity">
        select * from account where
        email = #{email}
    </select>
</mapper>

• namespace
  • 告诉 mybatis 依赖于哪个接口
• resultType
  • 返回值类型是什么