使用IDEA的MyBatis-plus快速入门小例子

使用IDEA的MyBatis-plus快速入门小例子

1.创建项目

使用IDEA软件，点击File -> New Project -> Spring Initializr -> next ,写好Group，Artfact，Name和Pakage，选择next，然后选择lombok（简化java代码插件），Spring Web 和Spring Data JDBC，最后选择完成即可。

2.导入MyBatis-Plus依赖

  <dependency>
       <groupId>com.baomidou</groupId>
       <artifactId>mybatis-plus-boot-starter</artifactId>
       <version>3.1.2</version>
  </dependency>
  <dependency>
       <groupId>com.baomidou</groupId>
       <artifactId>mybatis-plus-extension</artifactId>
       <version>3.1.2</version>
 </dependency>

3.修改application.proprerties为application.yml,建立数据连接

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mp?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8
    username: root
    password: 123456

4.创建实体User和UserMapper

（1）创建包entity，在包里创建User对象

@Data
public class User {
    //主键
    private Long id;
    //姓名
    private String name;
    //年龄
    private Integer age;
    //邮箱
    private String email;
    //直属上级
    private Long managerId;
    //创建时间
    private LocalDateTime createTime;
}

（2）创建dao包，在包里创建UserMapper接口类，这里要加上@Mapper和@Component注解,继承BaseMapper

@Mapper
@Component(value="UserMapper")
public interface UserMapper extends BaseMapper<User> {
}

5.在启动类上加上@MapperScan注解，扫描mapper

例如：

@SpringBootApplication
@MapperScan("com.mp.dao")
public class First2Application {

    public static void main(String[] args) {
        SpringApplication.run(First2Application.class, args);
    }

}

6.测试方法

@RunWith(SpringRunner.class)
@SpringBootTest
class First2ApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Test
    public void select(){
        List<User> list = userMapper.selectList(null);
        Assert.assertEquals(5,list.size());
        list.forEach(System.out::println);
    }

}