下載的視頻文件無法在Android的播放

Question

問題：
我下載的視頻文件不能從任何播放器上播放，更別說我的應用程序的VideoView，但它從URL中很好地扮演成VideoView。

什麼DONE：
我下載a video file，如果它不是在外部存儲，否則直接從網址到VideoView播放。
代碼的VideoView部分是這樣的：

final VideoView vvPlayer = (VideoView) findViewById(R.id.vvPlayer); 
MediaController mc = new MediaController(MainActivity.this); 
mc.setAnchorView(vvPlayer); 
vvPlayer.setMediaController(mc); 

if (videoFile.exists()) { 
    // vvPlayer.setVideoURI(Uri.fromFile(videoFile)); <-- Also Tried :(
    vvPlayer.setVideoPath(videoFile.getAbsolutePath()); 
    Toast.makeText(this, "Playing from local ...", Toast.LENGTH_SHORT).show(); 
} else { 
    vvPlayer.setVideoPath(VIDEO_PATH); 
    Toast.makeText(this, "Playing online & caching ...", Toast.LENGTH_SHORT).show(); 
    downloadVideoFile(); 
} 

的芯核部，即，downloadVideoFile()方法的的AsyncTask的the doInBackground()返回文件的內容作爲使用以下代碼的字符串：

@Override 
protected String doInBackground(Void... params) { 

    URLConnection conn; 
    try { 
     URL httpFileUrl = new URL(fileUrl); 
     conn = httpFileUrl.openConnection(); 
     conn.connect(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
     return null; 
    } 
    Log.d(TAG, "Connection opened"); 
    InputStream inputStream; 
    try { 
     inputStream = new BufferedInputStream(conn.getInputStream(), 4096); 
    } catch (IOException e) { 
     e.printStackTrace(); 
     return null; 
    } 

    BufferedReader bufferedReader = new BufferedReader(
           new InputStreamReader(inputStream)); 

    int responseLen = 0; 
    StringBuilder stringBuilder = new StringBuilder(); 
    String responseStr; 
    try { 
     while ((responseStr = bufferedReader.readLine()) != null) { 
      // Log.i(TAG, "Response read: " + responseStr); 
      stringBuilder.append(responseStr.trim()); 
      // ...my progress-bar related codes 
     } 
     inputStream.close(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
     return null; 
    } 

    responseStr = stringBuilder.toString(); 
    return responseStr; 
} 

獲取文件的內容後，我平凡保存使用下面的代碼在那些文件：

 try { 
      if (!APP_DIRECTORY.exists()) 
       APP_DIRECTORY.mkdirs(); 
      if (videoFile.createNewFile()) 
       Log.d(TAG, "Vide-file newly created"); 

      FileOutputStream fos = new FileOutputStream(videoFile); 
      fos.write(fileContent.getBytes()); 
      fos.flush(); 
      fos.close(); 
     } catch (IOException e) { 
      Log.d(TAG, "Exception for new creation of videoFile"); 
      e.printStackTrace(); 
     } 

最終結果是一個8.81 MB的文件，無法用任何視頻播放器打開爲視頻文件，更不用說我嘗試過的VideoView。

可能是我想的東西像編解碼器，編碼甚至簡單文件保存一部分？

Answer 1

Replace your doInBackground with this: 

@Override 
protected String doInBackground(Void... params) { 

    URLConnection conn; 
    try { 
     URL httpFileUrl = new URL(fileUrl); 
     conn = httpFileUrl.openConnection(); 
     conn.connect(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
     return null; 
    } 
    Log.d(TAG, "Connection opened"); 
    InputStream inputStream; 
    try { 
     inputStream = new BufferedInputStream(httpFileUrl.openStream(), 8192); 
OutputStream output = new FileOutputStream("/sdcard/downloadedfile.mp4"); 

byte data[] = new byte[1024]; 

      long total = 0; 

      while ((count = input.read(data)) != -1) { 
output.write(data, 0, count); 
} 
output.flush(); 
output.close(); 
      inputStream.close(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
     return null; 
    } 


    return null; 
} 


And in onPostExecute, 

@Override 
    protected void onPostExecute(String file_url) { 

     String videoPath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.mp4"; 
     // Now pass this path for playing video. 
    }