在Java中恢复http文件下载

 HttpURLConnection connection = (HttpURLConnection) url.openConnection();    if(ISSUE_DOWNLOAD_STATUS.intValue()==ECMConstant.ECM_DOWNLOADING){        File file=new File(DESTINATION_PATH);        if(file.exists()){  downloaded = (int) file.length();  connection.setRequestProperty("Range", "bytes="+(file.length())+"-");        }    }else{        connection.setRequestProperty("Range", "bytes=" + downloaded + "-");    }    connection.setDoInput(true);    connection.setDoOutput(true);    progressBar.setMax(connection.getContentLength());     in = new BufferedInputStream(connection.getInputStream());     fos=(downloaded==0)? new FileOutputStream(DESTINATION_PATH): new FileOutputStream(DESTINATION_PATH,true);     bout = new BufferedOutputStream(fos, 1024);    byte[] data = new byte[1024];    int x = 0;    while ((x = in.read(data, 0, 1024)) >= 0) {        bout.write(data, 0, x);         downloaded += x;         progressBar.setProgress(downloaded);    }

这不是我的代码，但是可以。