Strruts2+JQuery上传文件遇到的问题

使用JQuery的ajaxfileupload上传文件：

js：

function ajaxFileUpload(fileName){
	if(!btnEnabler){
		alert("文件上传中，请稍候...");
		return;
	}
	btnEnabler = false;
	
	//load the loading image
	$("#fileLoading")
		.ajaxStart(function(){
			$(this).show();
		})
		.ajaxComplete(function(){
			$(this).hide();
		});
	
	//file upload
	$.ajaxFileUpload({ 
		url:'<%=path%>/email/uploadAttach.action?fileName='+escape(escape(fileName)), 
		secureuri:false, 
		fileElementId:'oFile', 
		dataType: 'json', 
		success: function (data, status){
			allFilePath=allFilePath + data.msg + "<*>";
			showFile();

			//clear the file selection dialog box
			var obj = document.getElementById("oFile");
			obj.outerHTML=obj.outerHTML; 
			 
			btnEnabler = true;
		}, 
		error: function (data, status, e){
			alert("文件上传失败");

			//clear the file selection dialog box
			var obj = document.getElementById("oFile");
			obj.outerHTML=obj.outerHTML;  
			
			btnEnabler = true;
		}
	})
}

 页面部分：

 <input type="file" id="oFile" name="oFile" onchange="ajaxFileUpload(this.value);">

<font id="fileLoading" style="display:none"><img src="<%=path%>/resource/image/Emailimage/loading.gif" border="0" align="absmiddle">&nbsp;正在上传附件...</font>

 后台action：

private static final SimpleDateFormat fileNameSdf=new SimpleDateFormat("yyyyMMddHHmmss"); 
 
private File oFile;

 提供oFile的get/set方法;

 

public void uploadAttach() throws EmailException {
		System.out.println("uploadAttach() invoke..." );
		
		HttpServletRequest request = ServletActionContext.getRequest();
		HttpServletResponse response = ServletActionContext.getResponse();
		
    	String uploadPath = EmailUtil.getUploadPath();
    	String fileNamePrefix = fileNameSdf.format(new Date());  
    	String uploadFileName = Escape.unescape(request.getParameter("fileName"));
    	
    	String storeFileName = uploadPath + fileNamePrefix + uploadFileName;
        File storeFile = new File(storeFileName);   

        BufferedOutputStream bos = null;   
        BufferedInputStream bis = null;   
       
        try {   
            bos = new BufferedOutputStream(new FileOutputStream(storeFile));   
            bis = new BufferedInputStream(new FileInputStream(oFile));   
            int c;   
            while ((c = bis.read()) != -1) {   
                bos.write(c);   
                bos.flush();   
            }   
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("{msg:'"+fileNamePrefix + uploadFileName+"'}");
        } catch (IOException e) {   
            e.printStackTrace();   
            throw new EmailException("上传邮件附件出错！");
        } finally {   
            try { bos.close(); } catch (IOException e) {e.printStackTrace();}
            try { bis.close(); } catch (IOException e) {e.printStackTrace();}
        }   
        
	}

 困惑了半天的问题就是上传小于2M的文件没问题，但是上传大于2M的文件ajax返回error，action没有执行，找了半天是Struts2的default.properties配置文件对上传文件的限制为2M，要修改这个限制可以再struts.xml中修改这一常量

<constant name="struts.multipart.maxSize" value="20000000" />

 问题就搞定了！