SpringBoot整合Mybatis

1. 新建User表

CREATE DATABASE mybatis_demo;
USE mybatis_demo;CREATE TABLE user (id BIGINT PRIMARY KEY AUTO_INCREMENT,username VARCHAR(50) NOT NULL,email VARCHAR(100) NOT NULL UNIQUE,password VARCHAR(255) NOT NULL
);

2. 初始化项目

2.1 新建项目

这个项目是可以直接用IDEA创建的，就不给pom文件了。

创建好之后，记得去改改mvn的配置和jdk版本

2.2 配置数据库连接

数据库的ip、端口号、数据库名以及用户名和密码，改成自己的

spring:datasource:url: jdbc:mysql://192.168.171.135:3306/mybatis_demo?serverTimezone=UTC&useSSL=falseusername: new_userpassword: your_passworddriver-class-name: com.mysql.cj.jdbc.Drivermybatis:mapper-locations: classpath:mapper/*.xmlconfiguration:map-underscore-to-camel-case: true  # 下划线转驼峰 user_name  userName

2.3 完善项目的架子

3. 正式开始

3.1 新增用户

在UserMapper里写一个insert接口：

package com.example.demo.mapper;import com.example.demo.domain.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Options;@Mapper
public interface UserMapper {@Insert("INSERT INTO user (username, email, password) VALUES (#{username}, #{email}, #{password})")@Options(useGeneratedKeys = true, keyProperty = "id")  // 自动获取数据库生成的主键IDint insertUser(User user);
}

在UserService和测试类里编写调用和测试的代码

package com.example.demo.service;import com.example.demo.domain.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class UserService {@Autowiredprivate UserMapper userMapper;public int insertUser(User user) {return userMapper.insertUser(user);}
}

package com.example.demo.unit;import com.example.demo.domain.User;
import com.example.demo.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import static org.junit.jupiter.api.Assertions.assertEquals;@SpringBootTest
class UserServiceTest {@AutowiredUserService userService;@Testvoid insertUser(){int res=userService.insertUser(User.builder().email("123@example.com").password("password").username("urfread").build());assertEquals(1, res);}
}

这里可能会遇到重复录入的问题，后续再解决。

3.2 根据邮箱查询

@Select("SELECT * FROM user where email = #{email}")
User findUserByEmail(String email);

3.4 改密码 和 删除用户

@Update("UPDATE user SET password = #{password} WHERE email = #{email}")
int updateUserPassword(String password,String email);
@Delete("DELETE FROM user WHERE email = #{email}")
int deleteUserByEmail(String email);

3.5 用xml再写一遍

``UserMapper`只保留方法定义

package com.example.demo.mapper;import com.example.demo.domain.User;
import org.apache.ibatis.annotations.Mapper;@Mapper
public interface UserMapper {int insertUser(User user);User findUserByEmail(String email);int updateUserPasswordByEmail(String password, String email);int deleteUserById(Long id);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.demo.mapper.UserMapper"><insert id="insertUser" parameterType="com.example.demo.domain.User">insert into user (email,password,username)values (#{email},#{password},#{username})</insert><update id="updateUserPasswordByEmail">update user set password = #{password} where email = #{email}</update><delete id="deleteUserById" parameterType="java.lang.Long">delete from user where id = #{id}</delete><select id="findUserByEmail" resultType="com.example.demo.domain.User">SELECT * FROM user WHERE email = #{email}</select>
</mapper>

---

再往后，逻辑删除、只更新非空字段、分页查询、事务等内容我都不太熟，所以都放在进阶里了。

4. 进阶