安卓下載的文件大小比其實際尺寸更小

Question

我想更新我的應用程序自動
這是我使用

public void Update(String apkurl){ 
     try { 
      URL url = new URL(apkurl); 
      HttpURLConnection c = (HttpURLConnection) url.openConnection(); 
      c.setRequestMethod("GET"); 
      c.setDoOutput(true); 
      c.connect(); 

      String PATH = Environment.getExternalStorageDirectory() + "/download/"; 
      File file = new File(PATH); 
      file.mkdirs(); 
      File outputFile = new File(file, "DeliverReceipt.apk"); 
      FileOutputStream fos = new FileOutputStream(outputFile); 

      InputStream is = c.getInputStream(); 

      byte[] buffer = new byte[1024]; 
      int len1 = 0; 
      while ((len1 = is.read(buffer)) != -1) { 
       fos.write(buffer, 0, len1); 
      } 
      fos.close(); 
      is.close();//till here, it works fine - .apk is download to my sdcard in download file 

      /*Intent intent = new Intent(Intent.ACTION_VIEW); 
      intent.setDataAndType(Uri.fromFile(new File(Environment.getExternalStorageDirectory() + "/apk/" + "DeliverReceipt.apk")), "application/vnd.android.package-archive"); 
      startActivity(intent); //installation is not working   
      */ 
     } catch (IOException e) { 
      Toast.makeText(getApplicationContext(), "Update error!", Toast.LENGTH_LONG).show(); 
     } 
    } 

下載的文件中的代碼只是20KB大小，這是比原來少
我該如何解決這個問題？
謝謝
*注意：如果我在瀏覽器試試這個網址是工作，一個APK可以下載

Answer 1

你應該沖洗關閉該文件之前，用​​