在我的 Web 应用程序中，我想包含ClearCacheInterceptor，以便在执行注销操作后它应该清除捕获，以便如果用户单击后退按钮它不应该显示上一页。当我运行代码时它工作正常我可以登录执行其他操作但是当我单击注销时它显示错误。这是我的代码
public class ClearCacheInterceptor extends AbstractInterceptor{
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
public String intercept(ActionInvocation invocation) throws Exception {
ActionContext context=(ActionContext)invocation.getInvocationContext();
HttpServletResponse response=(HttpServletResponse)context.get(StrutsStatics.HTTP_RESPONSE);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
response.setDateHeader("Expires", 0);
String result=invocation.invoke();
System.out.println("check result="+result);
return result;
}
}
注销代码
public String logOut() {
String status = "";
if (true) {
session.clear();
session = null;
if (session instanceof org.apache.struts2.dispatcher.SessionMap) {
try {
((org.apache.struts2.dispatcher.SessionMap) session).invalidate();
} catch (IllegalStateException e) {
}
}
status = "success";
} else {
addActionError(getText("system.ERROR"));
status = "error";
}
return status;
}
我的 struts.xml 动作文件
<struts>
<!-- Configuration for the default package. -->
<constant name="struts.Devmode" value="false"></constant>
<constant name="struts.enable.DynamicMethodInvocation" value="false" />
<constant name="struts.custom.i18n.resources" value="ApplicationResources" />
<package name="default" extends="struts-default">
<interceptors>
<interceptor-stack name="defaultStack">
<interceptor-ref name="exception" />
<interceptor-ref name="alias" />
<interceptor-ref name="servletConfig" />
<interceptor-ref name="prepare" />
<interceptor-ref name="i18n" />
<interceptor-ref name="chain" />
<interceptor-ref name="debugging" />
<interceptor-ref name="profiling" />
<interceptor-ref name="scopedModelDriven" />
<interceptor-ref name="modelDriven" />
<interceptor-ref name="fileUpload" />
<interceptor-ref name="checkbox" />
<interceptor-ref name="staticParams" />
<interceptor-ref name="params">
<param name="excludeParams">dojo..*,d-..*,6..*</param>
</interceptor-ref>
<interceptor-ref name="conversionError" />
<interceptor-ref name="validation">
<param name="excludeMethods">input,back,cancel,browse</param>
</interceptor-ref>
<interceptor-ref name="workflow">
<param name="excludeMethods">input,back,cancel,browse</param>
</interceptor-ref>
</interceptor-stack>
<interceptor name="clear-cache" class="com.java.session.ClearCacheInterceptor" />
</interceptors>
<default-interceptor-ref name="defaultStack"/>
<action name="users">
<result>home.jsp </result>
</action>
<action name="UserAction" class="com.java.action.RegisterAction">
<result name="input">/signup.jsp</result>
<result name="success">/home.jsp</result>
<result name="error">/error.jsp</result>
</action>
<action name="trialregister">
<result>signup.jsp</result>
</action>
<action name="Activate" class="com.java.action.ActivationAction">
<result name="input">/error.jsp</result>
<result name="success">/home.jsp</result>
<result name="error">/test1.jsp</result>
</action>
<action name="verifyLogin" class="com.java.action.LoginAction" method="verifyLogin">
<result name="input">/home.jsp</result>
<result name="success">/test1.jsp</result>
</action>
<action name="logOut" class="com.java.action.LoginAction" method="logOut">
<interceptor-ref name="clear-cache"/>
<result name="error">/error.jsp</result>
<result name="success">/logout.jsp</result>
</action>
<action name="Back">
<result>/index.jsp</result>
</action>
<action name="Reroot">
<result>/index.jsp</result>
</action>
</package>
日志中的错误消息是
SEVERE: Servlet.service() for servlet default threw exception
java.lang.NullPointerException
at com.java.action.LoginAction.logOut(LoginAction.java:103)
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:601)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:229)
at com.java.session.ClearCacheInterceptor.intercept(ClearCacheInterceptor.java:37)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:504)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Thread.java:722)