java - java恢复下载需要很长时间

Question

这是我的代码

private static void DownloadFile() throws IOException {
    BufferedInputStream in = null;
    File file=new File("temporary.file");
    RandomAccessFile raf=null;
    long fSize=0;
    if(file.exists()){
        raf=new RandomAccessFile(file, "rw");
        fSize=raf.length();
        System.out.println("File Exists size is "+fSize );
    }
    else{//2210413
        raf=new RandomAccessFile(file, "rw");
    }
    URL mURL=new URL("http://down5.game.uc.cn/s/5/5
    /20130517175858a128ee_1750544ZFbuE.xcxxsdjb_1365659155330.apk");
    HttpURLConnection conn = (HttpURLConnection)mURL.openConnection();
    String byteRange = fSize + "-";
    conn.setRequestProperty("Range", byteRange);
    conn.setConnectTimeout(60000);
    conn.connect();
     in = new BufferedInputStream(conn.getInputStream());
     in.skip(fSize);
    int mEndByte=conn.getContentLength();
     System.out.println("Total size:: "+mEndByte );
    raf.seek(fSize);
    byte data[] = new byte[1024];
    int numRead;
    while(((numRead = in.read(data,0,1024)) != -1)){
        raf.write(data,0,numRead);
        fSize += numRead;
        }
     if (raf != null) {
         try {
             raf.close();
         } catch (IOException e) {}
     }if (in != null) {
         try {
             in.close();
         } catch (IOException e) {}
     }

);
}}

此方法工作正常，但需要很长时间才能恢复。我的问题是有没有有效的方法来做到这一点？在我的代码中，我认为in.skip(); 这需要时间。