【Mybatis Plus-01】CRUD简单使用

一、引入maven依赖

			com.baomidou
			mybatis-plus-boot-starter
			3.5.1

二、创建数据库表

CREATE TABLE `boot_user` (
  `id` int NOT NULL COMMENT '主键id',
  `username` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '用户名',
  `password` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '密码',
  `avatar` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '头像',
  `nickName` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '昵称',
  `address` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '地址',
  `email` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '邮箱',
  `birthday` date DEFAULT NULL COMMENT '生日',
  `age` int DEFAULT NULL COMMENT '年龄',
  `height` double(10,2) DEFAULT NULL COMMENT '身高',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `update_time` datetime DEFAULT NULL COMMENT '更新时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

三、在spring boot工程中创建 User.java

@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor
@TableName(value = "boot_user") //@TableName注解用来指定表名
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty("用户id")
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    @ApiModelProperty("用户名")
    private String username;

    @ApiModelProperty("密码")
    private String password;

    @ApiModelProperty("头像")
    private String avatar;

    @ApiModelProperty("昵称")
    //字段如果和数据库不匹配，需要使用@TableField注解指定字段名称
    @TableField(value = "nick_name")
    private String nickName;

    @ApiModelProperty("地址")
    private String address;

    @ApiModelProperty("邮箱")
    private String email;

    @ApiModelProperty("生日")
    private LocalDateTime birthday;

    @ApiModelProperty("年龄")
    private Integer age;

    @ApiModelProperty("身高")
    private Double height;

    @ApiModelProperty("创建时间")
    @TableField(value = "create_time")
    private LocalDateTime createTime;

    @ApiModelProperty("修改时间")
    @TableField(value = "update_time")
    private LocalDateTime updateTime;

UserMapper.java

public interface UserMapper extends BaseMapper<User> {

}

IUserService.java

public interface IUserService extends IService<User> {
   
}

UserServiceImpl.java

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {

}

UserMapper.xml

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cy.springboot.mapper.UserMapper">

mapper>

四、通用mapper的CRUD

MapperTests.java

增

@SpringBootTest
@RunWith(SpringRunner.class)
public class MapperTests {
    @Resource
    private UserMapper userMapper;
	
	//增：C
	@Test
    public void c(){
        User user=new User();
        user.setUsername("account");
        user.setPassword("qwe123");
        user.setNickName("普通用户");
        user.setAddress("河北");
        user.setEmail("dsad@123.com");
        user.setBirthday(new Date());
        user.setAge(10);
        user.setHeight(180.88);
        int insert = userMapper.insert(user);
        System.out.println(insert);
    }
}

打印sql

删

@SpringBootTest
@RunWith(SpringRunner.class)
public class MapperTests {
    @Resource
    private UserMapper userMapper;
	
	//删：D
	@Test
    public void d(){
		//根据id删除一条数据库数据，返回受影响的行数
        int i = userMapper.deleteById(3);
        System.out.println(i);
    }
}

打印sql

改

@SpringBootTest
@RunWith(SpringRunner.class)
public class MapperTests {
    @Resource
    private UserMapper userMapper;
	
	//改：U
	@Test
    public void u(){
        User user = new User();
        user.setId(2);
        user.setAddress("天津");
        int i = userMapper.updateById(user);
        System.out.println(i);
    }
}

打印sql

查

@SpringBootTest
@RunWith(SpringRunner.class)
public class MapperTests {
    @Resource
    private UserMapper userMapper;
	
	//查：r
    @Test
    public void r(){
        List<User> users = userMapper.selectList(null);
        System.out.println(users);
    }

打印sql