整合ssh的时候出现空指针java.lang.NullPointerException

转自：https://blog.csdn.net/koudailidexiaolong/article/details/9468857

HTTP Status 500 -

---

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
	com.dragon.action.IndexAction.execute(IndexAction.java:45)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
	com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
	com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
	org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
	org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.

以上是页面报错的信息但是在控制台没有报错 也进了action

之前我运行了好几次都是报的这个异常，进行了调试他只在action中调用了方法直接返回空指针  刚开始还以为是那块写错了

经过仔细的检查发现原来是 struts。xml中配置的问题

未修改之前是这样

<package name="default" namespace="/" extends="struts-default">
  <action name="index" class="com.dragon.action.IndexAction" >
   <result name="success">index.jsp</result>
  </action>
 </package>

修改之后

<package name="default" namespace="/" extends="struts-default">
  <action name="index" class="indexAction" >
   <result name="success">index.jsp</result>
  </action>
 </package>

仔细看了看哦原来是class的问题因为使用了ssh技术 需要用spring中定义的bean的id访问作为struts的class名