Immer große Verzögerungen beim Herunterladen von Dateien über Service

Question

Ich habe einen Service, der URLs zum Download erhält. Der Dienst lädt dann diese URLs herunter und speichert sie in einer Datei auf der SD-Karte.

Wenn ich mehr als 2 Elemente in die Download-Queue legen, ist mein Gerät unbrauchbar. Es gefriert fast. Riesige Verzögerungen und so weiter. Irgendeine Idee?

Sourcecode:

private static boolean downloading = false; 
    private static ArrayList<DownloadItem> downloads = new ArrayList<DownloadItem>(); 

    /** 
    * called once when the service started 
    */ 
    public static void start() { 
     Thread thread = new Thread(new Runnable() { 

      @Override 
      public void run() { 
       while (true) { 
        if (downloads.size() > 0 && !downloading) { 
         downloading = true; 
         DownloadItem item = downloads.get(0); 
         downloadSingleFile(item.getUrl(), item.getFile()); 
        } 
       } 
      } 
     }); 
     thread.start(); 
    } 

    public static void addDownload(DownloadItem item) { 
     downloads.add(item); 
    } 

    private static void downloadSuccessfullFinished() { 
     if (downloads.size() > 0) 
      downloads.get(0).setDownloaded(true); 
     downloadFinished(); 
    } 


    private static void downloadFinished() { 
     // remove the first entry; it has been downloaded 
     if (downloads.size() > 0) 
      downloads.remove(0); 
     downloading = false; 
    } 

    private static void downloadSingleFile(String url, File output) { 
     final int maxBufferSize = 4096; 

     HttpResponse response = null; 
     try { 
      response = new DefaultHttpClient().execute(new HttpGet(url)); 
      if (response != null 
        && response.getStatusLine().getStatusCode() == 200) { 
       // request is ok 
       InputStream is = response.getEntity().getContent(); 
       BufferedInputStream bis = new BufferedInputStream(is); 
       RandomAccessFile raf = new RandomAccessFile(output, "rw"); 
       ByteArrayBuffer baf = new ByteArrayBuffer(maxBufferSize); 
       long current = 0; 
       long i = 0; 

       // read and write 4096 bytes each time 
       while ((current = bis.read()) != -1) { 
        baf.append((byte) current); 
        if (++i == maxBufferSize) { 
         raf.write(baf.toByteArray()); 
         baf = new ByteArrayBuffer(maxBufferSize); 
         i = 0; 
        } 
       } 

       if (i > 0) // write the last bytes to the file 
        raf.write(baf.toByteArray()); 

       baf.clear(); 
       raf.close(); 
       bis.close(); 
       is.close(); 

       // download finished get start next download 
       downloadSuccessfullFinished(); 
       return; 
      } 
     } catch (Exception e) { 
      // not successfully downloaded 
      downloadFinished(); 
      return; 
     } 
     // not successfully downloaded 
     downloadFinished(); 
     return; 
    } 

Answer 1

Sie einen AsyncTask oder einen Thread, in dem Sie den Download-Vorgang starten verwenden sollen.