mybatisPlus-乐观锁

数据库中添加version字段

 自定义配置类中，添加乐观锁的拦截器

package com.atguigu.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@MapperScan(basePackages = "com.atguigu.mapper")
@Configuration
public class Mpconfig {

    //乐观锁插件
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        //1 创建MybatisPlusInterceptor拦截器对象
        MybatisPlusInterceptor mpInterceptor=new MybatisPlusInterceptor();
        //2 添加乐观锁拦截器
        mpInterceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());

        return mpInterceptor;
    }
}

MyMetaObjectHandler类中设置添加version时的默认值

  @Override
    public void insertFill(MetaObject metaObject) {
        this.setFieldValByName("version",1,metaObject);
    }

实体类上verison自动添加注解

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.Version;
import lombok.Data;

import java.util.Date;
import static com.baomidou.mybatisplus.annotation.FieldFill.*;

@Data
public class User {

    @Version
    @TableField(fill = INSERT)
    private Integer version;
}

测试代码

当执行更新sql时，version版本号会自动+1

  @Test
    public void updateUserById(){
        //先查询再更新
        User user = userMapper.selectById(11L);
        user.setName("hello");
        //更新时会比对当前版本号，相同会更新版本号+1
        int i = userMapper.updateById(user);
        System.out.println(i);
    }

 下面场景会更新失败

携带版本号为0，此时库里面版本号为2

  @Test
    public void updateUserById(){
        User user = userMapper.selectById(11L);
        user.setName("hello");
        user.setVersion(0);

        int i = userMapper.updateById(user);
        System.out.println(i);
    }