注:inputStream不能在二个不同的类之间赋予.只能直接得到!!

FTP远程下载的例子:
//设置此项即告诉SERVLET是下载文件,而不是网页或TXT.(可以弹出对话框)
 response.setContentType("APPLICATION/OCTET-STREAM");

//用IntputStream时,就用下面这个.
    ServletOutputStream  outputStream = response.getOutputStream();

//转换下载中文名的问题.
String fPath =new String(Filename.getBytes("GBK"), "ISO8859_1");

//设置下载的文件名与原文件名一样.
 response.setHeader("Content-Disposition",
                           "attachment; filename=\"" +  fPath +
                           "\"");
        System.out.println(refFile.getFilename());

        FTPClient ftpclient=new FTPClient();

//连接FTP服务器
      ftpclient.connection(severurl)

       
        if (refFile != null && (refFile.getFilesize() < 1024 * 1024 * 10)) {
          temRemote=new String(("\\" + refFile.getFilename()).getBytes("gb2312"), "iso-8859-1");
          inputStream = ftpclient.retrieveFileStream(temRemote);
          System.out.println("00001");
        }
        else if (refFile != null && (refFile.getFilesize() > 1024 * 1024 * 10)) {
          temRemote=new String((refFile.getMetaURL() + "\\" +
                                               refFile.getFilename()).getBytes("gb2312"), "iso-8859-1");
          inputStream = ftpclient.retrieveFileStream(temRemote);
        }
        System.out.println("<10M时=" + "\\" + refFile.getFilename());
        System.out.println(">10M时=" + refFile.getMetaURL() + "\\" +
                                               refFile.getFilename());
        int i;
        int chunk = inputStream.available();
        System.out.println("chunk数据长度是=" + chunk);
        //byte数组接受文件的数据
        byte[] buffer = new byte[chunk];
        int length = -1;
        if (inputStream == null) {
          System.out.println("输入流为空!!");
        }
       while((length=inputStream.read(buffer))!=-1){
         System.out.println("length数据长度是=" + length);
         outputStream.write(buffer, 0, length); //读入流,保存在BYTe数组中
       }