ServletFileUpload 上传时upload.parseRequest(request);为空

今天在页面提交到servlet上传时，遇到一小问题，

 DiskFileItemFactory factory = new DiskFileItemFactory();

 factory.setRepository(new File(tempPath));

 ServletFileUpload upload = new ServletFileUpload(factory);

 List<FileItem> fileItems = upload.parseRequest(req);

 

// 这里 fileItems一直为空

最后原因是被 web.xml中的 Filter过滤掉了

<filter>
		<filter-name>struts2</filter-name>
		<filter-class>
			org.apache.struts2.dispatcher.FilterDispatcher
		</filter-class>
	</filter>

	<filter-mapping>
		<filter-name>struts2</filter-name>
               <!-- 	<url-pattern>/*</url-pattern> -->
		<url-pattern>*.action</url-pattern>
	</filter-mapping>