enctype="multipart/form-data" 上传有关问题

<form action="hidden-uploadAttachment.action" method="post" enctype="multipart/form-data">  <input name="file" type="file"   style="padding:0px; "   <input type="submit" value="上传附件" name="agree"/></form>

<action name="hidden-uploadAttachment" class="com.ntsky.bbs.web.webwork.action.attachment.UploadAttachmentAction">            <interceptor-ref name="commonStack"/>            <interceptor-ref name="basicStack"/>            <result name="success">/hidden-uploadAttachment.jsp</result>           </action>

public class UploadAttachmentAction extends AttachmentActionSupport{          public String execute(){        if(logger.isDebugEnabled()){            logger.debug("该代码被执行...");        }               //..........上传代码省略           }