Mybatis-plus实现主键自增和自动注入时间的示例代码

mybatis-plus依赖导入

<dependency>
     <groupId>com.baomidou</groupId>
     <artifactId>mybatis-plus-boot-starter</artifactId>
     <version>3.3.2</version>
   </dependency>

建议使用3.3.0后的版本。

导入mybatis-plus就不用导入mybatis了，冲突！

连接数据库

spring.datasource.username=root
spring.datasource.password=19981204
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl//配置默认日志

设置主键自增

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
 @TableId(type = IdType.AUTO)
 private Long id;
 private String name;
 private Integer age;
 private String email;

}

使用注解 @TableId(type=IdType.AUTO),同时将数据库中的id字段设置为自增即可。

编写配置类来进行自动注入时间（继承元数据类并重写它的insertFill和updateFill方法）
使用注解@TableFiled(fill=FieldFill.INSERT)

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
 @TableId(type = IdType.AUTO)
 private Long id;
 private String name;
 private Integer age;
 private String email;
 @TableField(fill = FieldFill.INSERT)
 private LocalDateTime createTime;
 @TableField(fill = FieldFill.INSERT_UPDATE)
 private LocalDateTime updateTime;
}

package com.ls.handler;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
   import org.apache.ibatis.reflection.MetaObject;
   import org.springframework.stereotype.Component;

import java.time.LocalDateTime;

/**
* @author dell
*/
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
 @Override
 public void insertFill(MetaObject metaObject) {
   this.strictInsertFill(metaObject,"createTime", LocalDateTime.class,LocalDateTime.now());
   this.strictUpdateFill(metaObject,"updateTime",LocalDateTime.class,LocalDateTime.now());

}

@Override
 public void updateFill(MetaObject metaObject) {
   this.strictUpdateFill(metaObject,"updateTime",LocalDateTime.class,LocalDateTime.now());
 }
}

来源：https://segmentfault.com/a/1190000023287521