Android：BitmapFactory.decodeStream OutOfMemoryException - 是SoftReference的解決方案嗎？

Question

我得到一個OutOfMemoryException：

E/AndroidRuntime(3013): java.lang.OutOfMemoryError: bitmap size exceeds VM budget 
E/AndroidRuntime(3013):  at android.graphics.BitmapFactory.nativeDecodeStream(Native Method) 
E/AndroidRuntime(3013):  at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:375) 
E/AndroidRuntime(3013):  at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:394) 

在下面的功能：

static Bitmap downloadBitmap(String url) 
    { 
     final HttpClient client = new DefaultHttpClient(); 
     final HttpGet getRequest = new HttpGet(url); 

     try 
     { 
      HttpResponse response = client.execute(getRequest); 
      final int statusCode = response.getStatusLine().getStatusCode(); 

      // Check HTTP Status code 
      if (statusCode != HttpStatus.SC_OK) 
      { 
       debugPrint("ImageDownloader StatusCode Error " + statusCode + " while retrieving bitmap from " + url); 
       return null; 
      } 
      else; 


      final HttpEntity entity = response.getEntity(); 

      if (entity != null) 
      { 
       InputStream inputStream = null; 
       try 
       { 
        inputStream = entity.getContent(); 
        if(inputStream == null) 
        { 
         debugPrint("ImageDownloader::downloadBitmap() - INPUTSTREAM = NULL!!!!!!"); 
        } 
        else; 



        // THIS LINE IS GIVING THE ERROR 
        final Bitmap bitmap = BitmapFactory.decodeStream(new FlushedInputStream(inputStream)); 

        if(bitmap == null) 
        { 
         debugPrint("LocrPhoto::downloadBitmap() - about to return BITMAP =NULL!!!!!!"); 
        } 
        else; 

        return bitmap; 
       } 
       catch (Exception e) 
       { 
        // Could provide a more explicit error message for IOException or IllegalStateException 
        getRequest.abort(); 
        debugPrint("LocrPhoto::downloadBitmap() Error while decoding bitmap from " + url + "\n"+ e.toString()); 
       } 
       finally 
       { 
        if (inputStream != null) 
        { 
         inputStream.close(); 
        } 
        entity.consumeContent(); 
       } 
      } 
      else 
      { 
       debugPrint("LocrPhoto::downloadBitmap("+url+") - entity = NULL!!!!!"); 
      } 
     } 
     catch (Exception e) 
     { 
      // Could provide a more explicit error message for IOException or IllegalStateException 
      //getRequest.abort(); 
      debugPrint("LocrPhoto::downloadBitmap() Error while retrieving bitmap from " + url + "\n"+ e.toString()); 
     } 
     finally 
     { 
      if (client != null) 
      { 
       // CLOSE CONNECTION 
      } 
     } 
     debugPrint("LocrPhoto::downloadBitmap("+url+") - returning NULL at end of function"); 
     return null; 
    } 

FlushedInputStream（雖然我加入這個代碼之前得到了錯誤）：

// A Class to hopefully avoid the BitmapFactory.decodeStream() returning null bug 
    //  http://code.google.com/p/android/issues/detail?id=6066 
    static class FlushedInputStream extends FilterInputStream { 
     public FlushedInputStream(InputStream inputStream) { 
      super(inputStream); 
     } 

     @Override 
     public long skip(long n) throws IOException { 
      long totalBytesSkipped = 0L; 
      while (totalBytesSkipped < n) { 
       long bytesSkipped = in.skip(n - totalBytesSkipped); 
       if (bytesSkipped == 0L) { 
         int byt = read(); 
         if (byt < 0) { 
          break; // we reached EOF 
         } else { 
          bytesSkipped = 1; // we read one byte 
         } 
       } 
       totalBytesSkipped += bytesSkipped; 
      } 
      return totalBytesSkipped; 
     } 
    } 

基本上，我有一個下載圖像的活動，將它們放置在一個框架佈局中，並將幀放入和放出以進行幻燈片放映。 framelayout有兩個imageview兒童。

我見過有人說SoftReference被用來防止OOMExceptions，但我不明白這將如何應用到我的代碼（希望），以防止此錯誤。

任何人都可以解釋這可能是如何實現的嗎？

在此先感謝！ r3mo

Answer 1

我正在處理同樣的問題，因爲我發現問題是BitmapFactory.decodeStream的內存消耗（如日誌所示）。你必須做的是在調用BitmapFactory.decodeStream之前縮放位圖，你可以找到一篇很好的文章來解決你的問題！

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

希望它能幫助！