SpringBoot整合Mybatis 简单试用

1. 导入依赖

• 我使用MySQL，需要导入MySQL的驱动依赖
• 此外要在SpringBoot中使用Mybatis，则需要导入Mybatis启动器

        <dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.2</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency>

需要注意版本对应关系，我是用springboot2.7.14，则需要导入2.2或2.3的Mybatis启动器

2. 配置文件

在springboot的yaml配置文件中把连接数据库所需的spring.datasource和mybatis.mapper-locations配置好。

• mapper-locations我设置的是classpath:mapper/*.xml，一般都是在
  resource目录下创建一个mapper文件夹，然后把所有的mapper.xml放进去。因此mapper-locations设置为classpath:mapper/*.xml的意思就是扫描mapper文件夹下的所有xml文件作为mybatis的mapper
• spring.datasource则就是数据库连接所需的driver、url、username、password

mybatis:mapper-locations: classpath:mapper/*.xml
spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/mytestusername: rootpassword: root

3. 业务场景

dao层创建一个Mapper接口，注意需要用@Mapper标记

@Mapper
public interface UserMapper {User getUserByID(int id);
}

对应的在resource/mapper下创建对应的Mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.wonder.mapper.UserMapper"><select id="getUserByID" parameterType="int" resultType="com.wonder.entity.User">select * from users where id=#{id}</select>
</mapper>

其中用到的entity

package com.wonder.entity;
public class User {private long id;private String name;private String username;private String password;private java.sql.Timestamp createtime;private long roleid;public long getId() {return id;}public void setId(long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public java.sql.Timestamp getCreatetime() {return createtime;}public void setCreatetime(java.sql.Timestamp createtime) {this.createtime = createtime;}public long getRoleid() {return roleid;}public void setRoleid(long roleid) {this.roleid = roleid;}
}

用到的数据库表和其中的数据

4. Service层和Controller层

public interface UserService {User getUserByID(int id);
}

@Service
public class UserServiceImpl implements UserService {@AutowiredUserMapper userMapper;@Overridepublic User getUserByID(int id) {return userMapper.getUserByID(id);}
}

@Controller
public class UserController {@AutowiredUserService userService;@RequestMapping("/getUser")@ResponseBodypublic User getUserByID(@RequestParam("id") int id){return userService.getUserByID(id);}
}

5. 测试效果

启动程序，浏览器中输入http://localhost:8080/getUser?id=2

6. 额外记录

记录下在IDEA中最好安装MyBatisX插件，能够方便的在IDEA中进行mapper和xml之间的跳转。相当好用。