SpringBoot图文并茂详解如何引入mybatis与连接Mysql数据库

创建一个SpringBoot项目

其他不赘叙了，引入MyBaties、MySql依赖

创建mysql表

CREATE TABLE sp_users(
`id` INT PRIMARY KEY,
`username` VARCHAR(30),
`age` INT
);

刚开始一直出现这个错误，弄的我怀疑人生，结果是最后一行不能加',' ，物是人非。

INSERT INTO sp_users(id,`username`,`age`) VALUES(1,"张三",11);
INSERT INTO sp_users(id,`username`,`age`) VALUES(2,"李四",21);
INSERT INTO sp_users(id,`username`,`age`) VALUES(3,"游坦之",800);

编写实体类

因为引入了Lombok，所以直接用了

package com.you.domain;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class user {
   private int id;
   private String username;
   private int age;
}

配置application.yaml

#datasource
spring:
  datasource:
    url: jdbc:mysql:///springboot?serverTimezone=UTC
    username: root
    password: 你的密码
    driver-class-name: com.mysql.cj.jdbc.Driver

配置Mapper

方式一，创建UserMapper接口

package com.you.mapper;
import com.you.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;
import java.util.List;
@Mapper
@Repository
public interface UserMapper {
   @Select("select * from sp_users")
   public List<User> findAll();
}

配置测试类

package com.you.boot;
import com.you.boot.domain.User;
import com.you.boot.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
class BootMybatis03ApplicationTests {
   @Autowired
   private UserMapper userMapper;
   @Test
   public void testFindAll()
   {
       List<User> list = userMapper.findAll();
       System.out.println(list);
   }
}

效果图

方法二 XML文件配置

编写xml文件，namespace一定要复制全路径，Copy/Copy Reference

<?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.you.boot.mapper.UserXmlMapper">
   <select id="findAll" resultType="user">
       select * from sp_users
   </select>
</mapper>

编写UserXmlMapper接口，@Repository的作用是解决在测试类内爆红，虽然爆红不影响程序的运行。

package com.you.boot.mapper;
import com.you.boot.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;
import java.util.List;
@Mapper
@Repository
public interface UserXmlMapper {
   public List<User> findAll();
}

配置yaml，*Mapper值得是所有后缀是Mapper的xml文件

mybatis:
  mapper-locations: classpath:mapper/*Mapper.xml
  type-aliases-package: com.you.boot.domain

编写测试类

package com.you.boot;
import com.you.boot.domain.User;
import com.you.boot.mapper.UserMapper;
import com.you.boot.mapper.UserXmlMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
class BootMybatis03ApplicationTests {
   @Autowired
   private UserXmlMapper userXmlMapper;
   @Test
   public void testFindAll2()
   {
       List<User> list = userXmlMapper.findAll();
       System.out.println(list);
   }
}

效果

感叹

记得当初学MySQL的时候，编写sql语句非常的熟练，现在非常僵硬，认真写博客真的不失为一种复习的好方法。还有当初学SSM的时候，没好好学，没有扎扎实实的学，现在也挺后悔的。快速和详细真的不能兼得。别人的建议可以听听，但一定要坚守自己的内心。倚天照海花无数，流水高山心自知。

来源：https://blog.csdn.net/m0_59792745/article/details/125804386