Загрузка файлов в android

Question

Я пытаюсь написать приложение, которое загружает файлы в фоновом режиме. При сбое кода doInBackground() код выходит из строя. Это происходит, когда для выполнения задается значение false перед возвратом. Код следующим образом -

public class DownloadFile extends AsyncTask<String, Integer, String> { 
    private boolean doing; 
    private Activity activity; 
    private Intent intent; 
    private File beta; 
    private File alpha; 

    public DownloadFile(Activity act, Intent intent) { 
     this.activity = act; 
     this.intent = intent; 
     doing = false; 
    } 

    @Override 
    protected String doInBackground(String... sUrl) { 
     int fileCount = 0; 
     if (!download(sUrl[0] + "list.txt", 
       Environment.getExternalStorageDirectory() + "/alpha/list.txt")){ 
      setDoing(false); 
      return "Download failed";//list.txt could not be downloaded. return error message. 
     } 
     fileCount++; 

     beta = new File(Environment.getExternalStorageDirectory() + "/beta/"); 
     File betalist = new File(beta + "/list.txt"); 

     alpha = new File(Environment.getExternalStorageDirectory() + "/alpha/"); 
     File alphalist = new File(alpha + "/list.txt"); 

     //verify that the file is changed. 
     if (alphalist.lastModified() == betalist.lastModified()// these two are 
                   // never equal. 
       || alphalist.length() == betalist.length()) { // better to check 
                   // the length of 
                   // the files. 
      setDoing(false); 
      return "Nothing to download."; 
     } 



     try { 
      FileReader inAlpha = new FileReader(alphalist); 
      BufferedReader br = new BufferedReader(inAlpha); 
      String s; 

      // read the name of each file in a loop 
      while ((s = br.readLine()) != null) { 
//    if(fileExistsInBeta(s)){ 
//     copyFromBetaToAlpha(s); 
//     continue; 
//    } 
       // download the file. 
       //Url will truncate the trailing/so keep if statement as is. 
       if (!download(sUrl[0] + s, 
         Environment.getExternalStorageDirectory() + "/alpha/" 
           + s)){ 
        setDoing(false); 
        return "Failed at " + s;// the given file could not be downloaded. return error. 
       } 
       fileCount++; 
      } 
      br.close(); 
     } catch (FileNotFoundException e) { 
      // TODO Auto-generated catch block 
      Log.e("Pankaj", e.getMessage()); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      Log.e("Pankaj", e.getMessage()); 
     } catch (Exception e) { 
      Log.e("Pankaj", e.getMessage()); 
     } 
     Log.d("Pankaj", "Download Done"); 

     activity.overridePendingTransition(0, 0); 
     intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION); 
     activity.finish(); 

     Log.d("Pankaj", "MainActivity Killed"); 
     // rename alpha to beta 

     deleteSubFolders(beta.toString()); 
     beta.delete(); 
     alpha.renameTo(beta); 
     if (!alpha.exists()) { 
      alpha.mkdir(); 
     } 
     File upper = new File(alpha + "/upper/"); 
     if (!upper.exists()) 
      upper.mkdirs(); 
     File lower = new File(alpha + "/lower/"); 
     if (!lower.exists()) 
      lower.mkdirs(); 

//  ConfLoader.getInstance().reload();//to refresh the settings 
     // restart the activity 
     activity.overridePendingTransition(0, 0); 
     activity.startActivity(intent); 
     Log.d("Pankaj", "MainActivity restarted"); 

     // now reset done status so we can start again. 
     setDoing(false); 
     return "Download finished.";// return the status for onPostExecute. 
    } 

    private void copyFromBetaToAlpha(String fileName) { 
     File beta=new File(Environment.getExternalStorageDirectory()+"/beta/"+fileName); 
     File alpha=new File(Environment.getExternalStorageDirectory()+"/alpha/"+fileName); 
     try { 
      FileInputStream fis=new FileInputStream(beta); 
      FileOutputStream fos=new FileOutputStream(alpha); 
      byte[] buf=new byte[1024]; 
      int len; 
      while((len=fis.read(buf))>0){ 
       fos.write(buf, 0, len); 
      } 
      fis.close(); 
      fos.close(); 
     } catch (FileNotFoundException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     Toast.makeText(activity, result, Toast.LENGTH_LONG).show(); 
     super.onPostExecute(result); 
    } 

    public boolean download(String url, String file) { 
     boolean successful = true; 
     try { 
      URL u = new URL(url); 
      URLConnection conn = u.openConnection(); 
      conn.connect(); 
      int filelen = conn.getContentLength(); 
      File f = new File(file); 

      // skip download if lengths are same 
      // because the file has been downed fully. 
      if (f.exists() && filelen == f.length()) { 
       return successful; 
      } 

      InputStream is = u.openStream(); 
      DataInputStream dis = new DataInputStream(is); 

      byte[] buffer = new byte[1024]; 
      int length; 

      FileOutputStream fos = new FileOutputStream(f); 
      while ((length = dis.read(buffer)) > 0) { 
       fos.write(buffer, 0, length); 

      } 
      fos.close(); 
      buffer = null; 
      dis.close(); 
     } catch (MalformedURLException mue) { 
      Log.e("SYNC getUpdate", "malformed url error", mue); 
      successful = false; 
     } catch (IOException ioe) { 
      Log.e("SYNC getUpdate", "io error", ioe); 
      successful = false; 
     } catch (SecurityException se) { 
      Log.e("SYNC getUpdate", "security error", se); 
      successful = false; 
     } 
     return successful; 
    } 

    private void deleteSubFolders(String uri) { 
     File currentFolder = new File(uri); 
     File files[] = currentFolder.listFiles(); 

     if (files == null) { 
      return; 
     } 
     for (File f : files) { 
      if (f.isDirectory()) { 
       deleteSubFolders(f.toString()); 
      } 
      // no else, or you'll never get rid of this folder! 
      f.delete(); 
     } 
    } 

    public static int getFilesCount(File file) { 
     File[] files = file.listFiles(); 
     int count = 0; 
     for (File f : files) 
      if (f.isDirectory()) 
       count += getFilesCount(f); 
      else 
       count++; 

     return count; 
    } 

    public boolean isDoing() { 
     return doing; 
    } 

    /** 
    * @param doing 
    */ 
    public void setDoing(boolean doing) { 
     this.doing = doing; 
    } 

    private boolean fileExistsInBeta(final String fileName){ 
     boolean exists=false; 
     File beta=new File(Environment.getExternalStorageDirectory()+"/beta/"+fileName); 
     if(beta.exists()){ 
      String[] ext=beta.getName().split("."); 
      String extName=ext[ext.length-1]; 
      exists=(extName!="txt" && extName!="tmr" && extName!="conf"); 
     } 
     return exists; 
    } 

в основной деятельности -

public void run() { 
     if (!downloadFile.isDoing()) { 
      downloadFile.execute(ConfLoader.getInstance().getListUrl()); 
      downloadFile.setDoing(true); 
     } 
     // change the delay so that it covers the time for download and 
     // doesn't overlap causing multiple downloads jamming the bandwidth. 

     h.postDelayed(this, 1000);//check after 60 sec. 

    } 

в OnCreate() -

downloadFile = new DownloadFile(this, getIntent()); 
h = new Handler(); 
h.postDelayed(this, 1000); 

Любая помощь приветствуется. Заранее спасибо.

EDIT: Ошибка logcat Не удается выполнить задачу, задача которой уже запущена. Невозможно выполнить задачу: задача уже выполнена (задача может быть выполнена только один раз). EDIT: Возможно ли, что ошибка связана с тем, что я снова пытаюсь выполнить asynchtask в run(). Возможно, AsynchTask не разрешает повторный вход.

Answer 1

Попробуйте использовать этот 1. Сначала создайте диалог

@Override 
    protected Dialog onCreateDialog(int id) { 
    switch (id) { 
    case DIALOG_DOWNLOAD_PROGRESS: 
     mProgressDialog = new ProgressDialog(this); 
     mProgressDialog.setMessage("Downloading file.."); 
     mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
     mProgressDialog.setCancelable(false); 
     mProgressDialog.show(); 
     return mProgressDialog; 
    default: 
     return null; 
    } 
} 

1. Загрузки асинхронной задача

   class DownloadFileAsync extends AsyncTask<String, String, String> { 
   
   @SuppressWarnings("deprecation") 
   @Override 
   protected void onPreExecute() { 
   super.onPreExecute(); 
   
   showDialog(DIALOG_DOWNLOAD_PROGRESS); 
       } 
   
       @Override 
       protected String doInBackground(String... aurl) { 
   int count; 
   File root = android.os.Environment.getExternalStorageDirectory();    
   // 
   File dir = new File (root.getAbsolutePath()+"/Downl"); 
   if(dir.exists()==false) { 
        dir.mkdirs(); 
       } 
   File file = new File(dir, url.substring(url.lastIndexOf("/")+1)); //name of file 
       try { 
   
         URL url = new URL(aurl[0]); 
         URLConnection conexion = url.openConnection(); 
         conexion.connect(); 
   
         int lenghtOfFile = conexion.getContentLength(); 
         Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile); 
   
         InputStream input = new BufferedInputStream(url.openStream()); 
         OutputStream output = new FileOutputStream(file); 
   
         byte data[] = new byte[1024]; 
   
         long total = 0; 
   
         while ((count = input.read(data)) != -1) 
          { 
           total += count; 
           publishProgress(""+(int)((total*100)/lenghtOfFile)); 
           output.write(data, 0, count); 
          } 
   
         output.flush(); 
         output.close(); 
         input.close(); 
       } catch (Exception e) {} 
       return null; 
   
        } 
   
       protected void onProgressUpdate(String... progress) { 
   Log.d("ANDRO_ASYNC",progress[0]); 
   mProgressDialog.setProgress(Integer.parseInt(progress[0])); 
       } 
   
       @SuppressWarnings("deprecation") 
       @Override 
       protected void onPostExecute(String unused) { 
   dismissDialog(DIALOG_DOWNLOAD_PROGRESS); 
   Toast.makeText(DisplayActivity.this,"Successfully downloaded in phone memory.", Toast.LENGTH_SHORT).show(); 
   } 
       } 
   

2. Вызовите асинхронный новый DownloadFileAsync() выполнение (URL). // Передаем ур URL