caijian_的博客

https://blog.i1i1i.cn/archives/exception-error-stack-trace

所有Exception的父类都是java.lang.Throwable。异常分成两种。Error和Exception而一般Error不是人为能处理的。像out of memory就是虚拟机空间不够时会报这个而Exception分为运行时异常(RuntimeException)和非运行时异常.运行时异常就是RuntimeException其子类的异常。像常用的空指针NullPoi

No EntityManager with actual transaction available for current thread - cannot reliably process 'merge' call; nested exception is javax.persistence.TransactionRequiredException: No EntityManager with ...

Servlet.service() for servlet [springServlet] in context with path [] threw exception [Handler processing failed; nested exception is java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config...