令牌/令牌会话拦截器导致 HttpSession 上的空指针

Question

我正在开发 struts2 Web 应用程序，我正在使用令牌拦截器处理 CSRF 漏洞。

我所做的是关于成功和错误，我将将用户重定向到同一页面，但带有操作错误或成功消息。

<action name="saveApplicationForm" class="action.ApplicationFormAction" 
      method="saveApplicationForm">
        <interceptor-ref name="token" />
        <result name="invalid.token" type="tiles">applicationForm.tiles</result>    
        <result name="input" type="tiles">applicationForm.tiles</result>
</action>

没有令牌/令牌会话拦截器一切正常，但是当我使用拦截器时，我得到 NullPointerException。

堆栈跟踪

java.lang.NullPointerException: null
at action.ApplicationFormAction.saveApplicationForm(ApplicationFormAction.java:218) ~[ApplicationFormAction.class:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_67]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_67]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_67]
at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_67]
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:450) [xwork-core-2.3.16.3.jar:2.3.16.3]
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:289) [xwork-core-2.3.16.3.jar:2.3.16.3]
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:252) [xwork-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.interceptor.TokenInterceptor.handleValidToken(TokenInterceptor.java:193) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.interceptor.TokenInterceptor.handleToken(TokenInterceptor.java:154) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.interceptor.TokenInterceptor.doIntercept(TokenInterceptor.java:142) [struts2-core-2.3.16.3.jar:2.3.16.3]
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) [xwork-core-2.3.16.3.jar:2.3.16.3]
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) [xwork-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:562) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99) [struts2-core-2.3.16.3.jar:2.3.16.3]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.63]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.63]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) [catalina.jar:7.0.63]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) [catalina.jar:7.0.63]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) [catalina.jar:7.0.63]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) [catalina.jar:7.0.63]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) [catalina.jar:7.0.63]
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957) [catalina.jar:7.0.63]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) [catalina.jar:7.0.63]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423) [catalina.jar:7.0.63]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079) [tomcat-coyote.jar:7.0.63]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620) [tomcat-coyote.jar:7.0.63]
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318) [tomcat-coyote.jar:7.0.63]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_67]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_67]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-coyote.jar:7.0.63]
at java.lang.Thread.run(Thread.java:745) [na:1.7.0_67]

动作类

public class ApplicationFormAction extends ActionSupport implements ModelDriven<ApplicationFormBean>, SessionAware
{
   private Map<String, Object> session; 
    // getter and setter

   public String saveApplicationForm()
   {
      // getting nullpointer here
     ApplicationFormBean sessApplicationFormBean = (ApplicationFormBean) this.session.get(SESSION_KEY_APPLICANT);
   }

}

1. 代码有什么问题？

2. 不在同一页面上重定向会导致问题（提交的令牌 会与新生成的令牌不同）？

3. 如果是，那么我应该如何处理这种情况而不重定向到其他页面？

Answer 1

<action name="saveApplicationForm" class="action.ApplicationFormAction" 
      method="saveApplicationForm">
        <interceptor-ref name="token" />
        <result name="invalid.token" type="tiles">applicationForm.tiles</result>    
        <result name="input" type="tiles">applicationForm.tiles</result>
</action>

您正在运行仅令牌拦截器。您需要运行整个堆栈，其中包含令牌拦截器。否则强制拦截器，如 Parameter Interceptor 和 ModelDriven Interceptor（因为您使用的是 ModelDriven）将不会运行，不会设置参数并且您将得到 NullPointerException。将其更改为：

<action name="saveApplicationForm" class="action.ApplicationFormAction"
      method="saveApplicationForm">
        <interceptor-ref name="defaultStack" />
        <interceptor-ref name="token" />
        <result name="invalid.token" type="tiles">applicationForm.tiles</result>    
        <result name="input" type="tiles">applicationForm.tiles</result>
</action>

还要注意术语，你不是在重定向任何东西，你只是在调度。重定向意味着一组完全不同的问题，例如参数丢失，并且只发生在redirect 和redirectAction 结果中。