jsp 和servlet 的一个问题

[didiaogao]

我在做一个文件上传的功能。
当点击上传后，需要时时的返回文件上传的进度。在页面上显示进度条。

我现在是在js里面用ajax 调用servlet。然后用servlet调用文件上传的处理类。。这个文件上传的进度在这个类里面。我怎么能时时的返回到页面啊？

js

	http_request = false;   
		       		//下面需要建立一个XMLHttpRequest对象,用它进行服务器请求,针对不同浏览器建立方法不同   
		      		if (window.XMLHttpRequest)   
		    		{ // Mozilla, Safari,...   
		           		http_request = new XMLHttpRequest();   
		          		if (http_request.overrideMimeType)   
		           		{   
		                	http_request.overrideMimeType('text/xml');   
		            	}   
		       		}   
		       		else if (window.ActiveXObject)   
		       		{ // IE   
			         	try {   
			               http_request = new ActiveXObject("Msxml2.XMLHTTP");   
			          	}   
			         	catch (e)   
			         	{   
			               	try  
			             	{	   
			              		http_request = new ActiveXObject("Microsoft.XMLHTTP");   
			                }   
			               catch (e) {}   
			         	}   
		       		}   
		         
				     if (!http_request) {   
				          alert('出现错误,不能建立一个XMLHTTP实例!');   
				          return false;   
				     }   
				     //var url = "servlet/UploadServlet?filepath="+filepath;
				     var url = "servlet/UploadServlet?filepath="+"F://ScreenKinescope.rar";
				    
				     //funccallback为请求返回后要调用的javascript方法   
				     http_request.onreadystatechange = funccallback;   
				     //该请求用get方式发送至url为/servlet/CheckServlet的Servlet,url可以带参数或数据方式同一般url传值,Servlet请看后面代码   
				     //http_request.open('GET',url, true);   
				     //http_request.send(null);   
				     //如果要使用HTTP POST方式,必须要对 XMLHttpRequest 对象设置一个 Content-Type 头，使用以下语句(url中也可包含参数)：   
				     http_request.open('POST',url, true);   
				     http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");   
				     http_request.send(null);   
					//每隔5秒循环一次服务器请求   
					setTimeout('startProgress()',1000); 

servlet：

String filepath = request.getParameter("filepath");
			String filepathF ="";
			if (filepath.contains("/")) {
				filepathF = filepath.substring(filepath.lastIndexOf("/") + 1);
			}
                          ContinueFtp c = new ContinueFtp();
c.connect("localhost", 21, "userid", "gao");
			c.u(filepath, "/"+filepathF);

文件上传的具体类：

public UploadStatus uploadFile(String remoteFile, File localFile,
			FTPClient ftpClient, long remoteSize) throws IOException {
		UploadStatus status;
		// 显示进度的上传
		long step = localFile.length() / 100;
		long process = 0;
		long localreadbytes = 0L;
		//InputStream raf = new FileInputStream(localFile);
		RandomAccessFile raf = new RandomAccessFile(localFile, "r");
		OutputStream out = ftpClient.appendFileStream(new String(remoteFile
				.getBytes("GBK"), "iso-8859-1"));
		// 断点续传
		if (remoteSize > 0) {
			ftpClient.setRestartOffset(remoteSize);
			process = remoteSize / step;
			raf.seek(remoteSize);
			localreadbytes = remoteSize;
		}
		byte[] bytes = new byte[1024];
		int c;
		while ((c = raf.read(bytes)) != -1) {
				out.write(bytes, 0, c);
			localreadbytes += c;
			if (localreadbytes / step != process) {
				process = localreadbytes / step;
				UploadServlet.a = process;
				System.out.println("上传进度:" + process);
				// TODO 怎么把这个process这个变量时时的传到jsp页面上啊
			}
		}
		out.flush();
		raf.close();
		out.close();
		boolean result = ftpClient.completePendingCommand();
		if (remoteSize > 0) {
			status = result ? UploadStatus.Upload_From_Break_Success
					: UploadStatus.Upload_From_Break_Failed;
		} else {
			status = result ? UploadStatus.Upload_New_File_Success
					: UploadStatus.Upload_New_File_Failed;
		}
		return status;
	}

[桃园闲人]

你在servlet中不断的out进度信息给页面，当全部都上传完了，你在关闭out流。这样试试看，我也没做过这个，不知道可行否。