TransactionRequiredException: No EntityManager with actual transaction available for current thread

错误描述全称：

javax.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call

原因：

没有在事务内进行表更新插入或者删除操作。

解决办法：

@RequestMapping("save")
@Transactional
public void save(HttpServletRequest request , HttpServletResponse response , User user){

}

在方法上头加入注解

@Transactional