MybatisPlus的乐观锁

Mybatis Plus添加乐观锁

1.乐观锁和悲观锁概念和理解

相关的定义和概念在学习Redis的事务已经做过笔记，这里就不重复写了

2.Mybatis Plus实现乐观锁

1. 此处是在Mybatis Plus的自动填充的代码上进行修改

2. 给数据库添加一个version字段
   

3. 给实体类添加对应的字段

package com.pning.pojo;

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.Version;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
    private Date autoTime;//通过数据库字段设定默认值，数据库自己在插入的时候填充时间

    @TableField(fill = FieldFill.INSERT)
    private Date creatTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;

    @Version
    private int version;
}

4. 注册组件

package com.pning.conf;

import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@EnableAutoConfiguration
@Configuration
public class MybatisPlusConfig {
    @Bean
    public OptimisticLockerInterceptor optimisticLockerInterceptor() {
        return new OptimisticLockerInterceptor();
    }
}

5. 启动测试

 @Test
    public void OptimisticLockingSuccess(){
        //线程1
        User user1 = userMapper.selectById("1l");
        user1.setName("P_ning");
        //假如这时候有一个线程插入
        //线程2
        User user2 = userMapper.selectById("1l");
        user2.setName("Pning");
        userMapper.updateById(user2);//更新成功
        userMapper.updateById(user1);//更新失败
    }