MyBatis-Plus 快速入门案例(小白教程)

<!--lombok-->
<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <optional>true</optional>
</dependency>
<!--mybatis plus 启动器-->
<dependency>
  <groupId>com.baomidou</groupId>
  <artifactId>mybatis-plus-boot-starter</artifactId>
  <version>3.1.0</version>
</dependency>
<!--mysql 驱动-->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
</dependency>

#创建用户表
CREATE TABLE user (
  id BIGINT(20) PRIMARY KEY NOT NULL COMMENT '主键',
  name VARCHAR(30) DEFAULT NULL COMMENT '姓名',
  age INT(11) DEFAULT NULL COMMENT '年龄',
  email VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
  manager_id BIGINT(20) DEFAULT NULL COMMENT '直属上级id',
  create_time DATETIME DEFAULT NULL COMMENT '创建时间',
  CONSTRAINT manager_fk FOREIGN KEY (manager_id)
    REFERENCES user (id)
) ENGINE=INNODB CHARSET=UTF8;

#初始化数据：
INSERT INTO user (id, name, age, email, manager_id
	, create_time)
VALUES (1087982257332887553, '大boss', 40, 'boss@baomidou.com', NULL
		, '2019-01-11 14:20:20'),
	(1088248166370832385, '王天风', 25, 'wtf@baomidou.com', 1087982257332887553
		, '2019-02-05 11:12:22'),
	(1088250446457389058, '李艺伟', 28, 'lyw@baomidou.com', 1088248166370832385
		, '2019-02-14 08:31:16'),
	(1094590409767661570, '张雨琪', 31, 'zjq@baomidou.com', 1088248166370832385
		, '2019-01-14 09:15:15'),
	(1094592041087729666, '刘红雨', 32, 'lhm@baomidou.com', 1088248166370832385
		, '2019-01-14 09:48:16');

import lombok.Data;

import java.util.Date;

/**
 * @Auther: IT贱男
 * @Date: 2019/6/10 14:35
 * @Description:这里没有Setter、Getter方法是因为小编使用了@Data注解
 */
@Data
public class User {

  private Long id;

  private String name;

  private Integer age;

  private String email;

  private Long managerId;

  private Date createTime;

}

spring:
 datasource:
  driver-class-name: com.mysql.jdbc.Driver
  username: root
  password: 123456
  url: jdbc:mysql://127.0.0.1:3306/mdp?userSSL=false

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.demo.model.User;

/**
 * @Auther: IT贱男
 * @Date: 2019/6/10 14:40
 * @Description: User对象持久层
 */
public interface UserMapper extends BaseMapper<User> {
}

@SpringBootApplication
@MapperScan("com.example.demo.mapper.**")
public class DemoApplication {

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

}

@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {

  @Autowired
  private UserMapper userMapper;

  @Test
  public void contextLoads() {
    // 查询所有数据
    List<User> users = userMapper.selectList(null);
    users.forEach(System.out::println);
    // 数据库中的数据默认初始5条，则判断查询出来的集合数量是否等于5
    Assert.assertEquals(5, users.size());
  }
}