java ftp下载的一个小问题（人民币100元）

    protected void doPost(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

        String sufix = request.getParameter("s");

        String path = request.getParameter("p") + "." + sufix;

        try {

            String fileName = request.getParameter("f").trim();

            int c = fileName.lastIndexOf(".");

            String name = fileName.substring(0, c > 0 ? c : fileName.length())

                    + "." + sufix;

            response.setContentType("application/octet-stream");

            response.setHeader("Content-Disposition", "attachement;filename="

                    + new String(name.getBytes("GBK"), "ISO-8859-1"));

            File file = new File(Const.getCurrentUtterlyPath() + path);

            if (!file.exists()) {

                throw new IOException(fileName + ",所下载的文件不存在!");

            }

            response.setContentLength(Integer.parseInt(file.length() + ""));

            InputStream fs = new FileInputStream(file);

            OutputStream os = response.getOutputStream();

            byte[] buff = new byte[1024];

            int readCount = 0;

            while ((readCount = fs.read(buff)) != -1) {

                os.write(buff, 0, readCount);

            }

            if (fs != null) {

                fs.close();

            }

            if (os != null) {

                os.close();

            }

        } catch (IOException e) {

            LOG.error("error: " + e.getMessage() + ",path: " + path);

            throw e;

        }

        response.setStatus(response.SC_OK);

        response.flushBuffer();

    }

/** */

	/**

	 * 从FTP服务器上下载文件,支持断点续传

	 * 

	 * @param remote

	 *            远程文件路径

	 * @param local

	 *            本地文件路径

	 * @return 上传的状态

	 * @throws Exception

	 */

	public DownloadStatus downloadFile(String remote, String local)

			throws Exception {

		ftpClient.setControlEncoding("iso-8859-1");	

		FtpConnect();	

		

		// 设置被动模式

		ftpClient.enterLocalPassiveMode();

		// 设置以二进制方式传输

		ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

		DownloadStatus result = null;	

		// 检查远程文件是否存在

		FTPFile[] files = ftpClient.listFiles(new String(

				remote.getBytes("utf-8"), "iso-8859-1"));

		if (files.length != 1) {

			//System.out.println("远程文件不存在");

			return DownloadStatus.Remote_File_Noexist;

		}

		

		long lRemoteSize = files[0].getSize();

		File f = new File(local + remote);

		this.createDir(local + remote);

		// 本地存在文件，进行断点下载

		if (f.exists()) {

			long localSize = f.length();

			// 判断本地文件大小是否大于远程文件大小

			if (localSize >= lRemoteSize) {

				//System.out.println("本地文件大于远程文件，下载中止");

				return DownloadStatus.Local_Bigger_Remote;

			}



			// 进行断点续传，并记录状态

			FileOutputStream out = new FileOutputStream(f, true);

			ftpClient.setRestartOffset(localSize);

			InputStream in = ftpClient.retrieveFileStream(new String(remote

					.getBytes("utf-8"), "iso-8859-1"));

			byte[] bytes = new byte[1024];

			int c;

			while ((c = in.read(bytes)) != -1) {

				out.write(bytes, 0, c);

			}

			in.close();

			out.close();

			boolean isDo = ftpClient.completePendingCommand();

			if (isDo) {

				result = DownloadStatus.Download_From_Break_Success;

			} else {

				result = DownloadStatus.Download_From_Break_Failed;

			}

		} else {

			OutputStream out = new FileOutputStream(f);

			InputStream in = ftpClient.retrieveFileStream(new String(remote

					.getBytes("utf-8"), "iso-8859-1"));

			byte[] bytes = new byte[1024];

			int c;

			while ((c = in.read(bytes)) != -1) {

				out.write(bytes, 0, c);



			}

			in.close();

			out.close();

			

			boolean upNewStatus = ftpClient.completePendingCommand();

			this.disconnect();

			if (upNewStatus) {

				result = DownloadStatus.Download_New_Success;

			} else {

				result = DownloadStatus.Download_New_Failed;

			}



		}

		return result;

	}