SpringBoot图文并茂详解如何引入mybatis与连接Mysql数据库
作者：游坦之
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。
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