struts2檔案下載出現Can not find a java.io.InputStream with the name的錯誤

 

struts2檔案下載出現Can not find a java.io.InputStream with the name的錯誤
JavaApacheServlet

    今天在用struts2就行檔案下載時出現如下錯誤：

 

Java代碼

1. Servlet.service() for servlet default threw exception   
2. java.lang.IllegalArgumentException: Can not find a java.io.InputStream with the name [imageStream] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
     
3.     at org.apache.struts2.dispatcher.StreamResult.doExecute(StreamResult.java:189)   
4.     at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:178)   
5.     at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:348)   
6.     at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:253)   
7.     at com.best.top.validate.TopInterceptor.intercept(TopInterceptor.java:47)   
8.     at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)   
9.     at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)   
10.     at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)   
11.     at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)   
12.     at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50)   
13.     at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:504)   
14.     at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419)  

Servlet.service() for servlet default threw exceptionjava.lang.IllegalArgumentException: Can not find a java.io.InputStream with the name [imageStream] in the invocation stack. Check the <param name="inputName"> tag specified for this action.at org.apache.struts2.dispatcher.StreamResult.doExecute(StreamResult.java:189)at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:178)at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:348)at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:253)at com.best.top.validate.TopInterceptor.intercept(TopInterceptor.java:47)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)

 

     說實話這個提示真有誤導人的嫌疑，剛開始還以為是名稱不對，估計一般人看到這個提示都這樣想。然後查看StreamResult的原始碼才發現是因為InputStream為null的緣故，汗一個。看下源碼：

 

Java代碼

1. if (inputStream == null) {   
2.                 // Find the inputstream from the invocation variable stack
     
3.                 inputStream = (InputStream) invocation.getStack().findValue(conditionalParse(inputName, invocation));   
4.             }   
5.   
6.             if (inputStream == null) {   
7.                 String msg = ("Can not find a java.io.InputStream with the name [" + inputName + "] in the invocation stack. " +   
8.                     "Check the <param name=\"inputName\"> tag specified for this action.");   
9.                 LOG.error(msg);   
10.                 throw new IllegalArgumentException(msg);   
11.             }