mybatis并发问题解决,参考hibernate
银行两操作员同时操作同一账户就是典型的例子。比如A、B操作员同时读取一余额为1000元的账户,A操作员为该账户增加100元,B操作员同时为该账户减去 50元,A先提交,B后提交。 最后实际账户余额为1000-50=950元,但本该为 1000100-50=1050。这就是典型的并发
银行两操作员同时操作同一账户就是典型的例子。比如A、B操作员同时读取一余额为1000元的账户,A操作员为该账户增加100元,B操作员同时为该账户减去 50元,A先提交,B后提交。 最后实际账户余额为1000-50=950元,但本该为 1000+100-50=1050。这就是典型的并发问题
一个简单的解决办法:更新的时候给版本号字段加上 1,然后 UPDATE 会返回一个更新结果的行数,通过这个行数去判断。
update account set price = #price #,version=version+1
where id=#id# and version=#vsersion#
如果更新执行返回的数量是 0 表示产生并发修改了,需要重新获得最新的数据后再进行更新操作。
Hibernate、JPA 等 ORM 框架或者实现,是使用版本号,再判断 UPDATE 后返回的数值,如果这个值小于 1 时则抛出乐观锁并发修改异常。

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