Can not find a java.io.InputStream with the name [downloadFile] in the invocation stack问题解决-优快云博客

本文详细介绍了在使用Struts2进行文件下载时遇到的常见问题及解决方法，包括错误提示解读、代码修复步骤以及可能导致问题的常见原因分析。

2010-1-22 9:45:03 org.apache.struts2.dispatcher.StreamResult doExecute
严重: Can not find a java.io.InputStream with the name [inputStream] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
2010-1-22 9:45:03 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.IllegalArgumentException: Can not find a java.io.InputStream with the name [inputStream] 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.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:221)

==========================解决办法===========================
这个错误报的真有点误导人呀,我还一直以为我struts.xml中<param name="inputName">inputStream</param>和action中的方法名getInputStream()不一致的问题,大家如果也碰到此类问题,直接打印
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
System.out.println(in);

如果打印为NULL的话,恭喜您,问题得以解决,问题的原因是这个流的realPath路径错误,像我的,
//String realPath=ServletActionContext.getServletContext().getRealPath("/uploadImages")+ "/"+name; 路径错误

String realPath="/uploadImages/"+name;正确的
=====================================================
没明白的,请看下面的详细说来
怪呀,我的配置应该没错呀
页面上:
<a href="fileDownload.action?fileName=<s:property value ="imageName" />">下载此图片</a>
struts.xml中
----------------------------------------------------------

<action name="fileDownload"
class="com.test.action.filedown.FileDownloadAction">
<result name="success" type="stream">

<param name="contentType">
application/octet-stream;charset=ISO8859-1
</param>
<param name="contentDisposition">
attachment;filename="${downloadFileName}"
</param>

<param name="inputName">inputStream</param>
<param name="bufferSize">4096</param>
</result>
</action>
----------------------------------------------------------
action中
----------------------------------------------------------
private String fileName;// 初始的通过param指定的文件名属性 set get

/** 文件名转换编码防止中文乱码*/
public String getDownloadFileName() {
String fileName=ServletActionContext.getRequest().getParameter("fileName");
String downFileName = fileName;
try {
downFileName = new String(downFileName.getBytes(), "ISO8859-1");
} catch (Exception e) {
e.printStackTrace();
}
return downFileName;
}
//下载的流
public InputStream getInputStream() {
String name=this.getDownloadFileName();
//String realPath=ServletActionContext.getServletContext().getRealPath("/uploadImages")+ "/"+name; 路径错误
String realPath="/uploadImages/"+name;
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
if(null==in){
System.out.println("Can not find a java.io.InputStream with the name [inputStream] in the invocation stack. Check the <param name=\"inputName\"> tag specified for this action.检查action中文件下载路径是否正确.");
}
return ServletActionContext.getServletContext().getResourceAsStream(realPath);
}

@Override
public String execute() throws Exception {
return SUCCESS;
}