发现的问题

在做项目的时候出现了这个异常：ognl.NoSuchPropertyException

java.lang.IllegalAccessException: Class ognl.OgnlRuntime can not access a member of

引起这种原因就是属性名称的不规范！！比如 "nTitle"、“pID”这样的属性名生成set和get方法是不规范的！

虽然代码没错，但是就会出现这个异常；

 

关于ssh中的问题：当我们在po层有集合属性时，我们应该显示的初始化集合属性，否则程序运行时会抛出空指针异常，

这个异常与hibernate无关，当程序对该集合属性添加属性时，如果没有初始化就会引发空指针异常。

 

 

org.hibernate.MappingException: Could not determine type for.......

hibernate集成在spring文件中，
在属性及get方法上都可以注解，结果hibernate默认只读属性上的注解，忽略 get方法上的注解，

所以特别是在一对多，一对一关系，多对多关系映射时，虽然在get方法上做了配置，但hibernate没有读取该注解，

才报 Could not determine type XXXx的错误；到底怎么在get方法上配置才有效，自己百度去吧。

 

 

org.hibernate.MappingException: Unknown entity: java.lang.Integer

今天发现自己写的hibernate中出现这个异常；其实是session.delete（）中的参数是个对象；

而我传的是个ID int型的；

 

 

八月 22, 2014 8:30:09 下午 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userAction' defined in file [D:\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\szwproj\WEB-INF\classes\com\action\UserAction.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.action.UserAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1007)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:953)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:626)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4210)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4709)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.action.UserAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:163)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1000)
    ... 28 more
Caused by: java.lang.NullPointerException
    at org.apache.struts2.ServletActionContext.getRequest(ServletActionContext.java:112)
    at com.action.UserAction.<init>(UserAction.java:33)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
    ... 30 more

一直出这个错误是因为UserAction中有private HttpSession session = ServletActionContext.getRequest().getSession();