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我开发了下面的类来接收带有标题（22字节）发送的图像，首先我解码标题以检查图像正确性然后我解码图像但并非所有图像都被解码，有时它返回SkImageDecoder::Factory returned null。我正在使用这个Android 教程来inSampleImage.

public class SocketServerStreamDataThread extends Thread {

    private Socket streamSocket;
    MainActivity mainActivity ;
    ImageView  displayedImage ;

    Bitmap bitmapImageToDisplay = null;
    byte[] dataBuffer = new byte[1048576];

    boolean result ;

    protected static boolean mReceivingStop; // Flag used to start and stop transmitting data

    SocketServerStreamDataThread(Socket socket, MainActivity mainActivityReceived, ImageView displayedImageView) {
        streamSocket = socket;
        // received activity to work on it in our java file
        mainActivity = mainActivityReceived ;
        // received image UI component to display
        displayedImage = displayedImageView;
    }

    @Override
    public void run() {
        /* Receiving the image */
        try {
            DecodeData decodeData = new DecodeData();
            // call DecodeData to get Image data from stream
            while (mReceivingStop == false) {
                if (bitmapImageToDisplay == null) {
                    InputStream inputStream = streamSocket.getInputStream();
                    if (inputStream.read(dataBuffer) > -1) {
                        // Call the class to decode received stream and return integer with the state of the decoding of the received data
                        // result = 0  ; means that decoding header is successful.
                        // result = -1 ; means that there is a problem in decoding header.
                        byte [] dataHeaderReceived = Arrays.copyOf(dataBuffer, 23) ;
                        result = decodeData.iDecodeReceiveData(dataHeaderReceived);
                        // Evalute the received data
                        if (result == false) {
                            /* Fault on application */
                            /* Close socket */
                            streamSocket.close();
                            mReceivingStop = true;
                        }

                        if (result == true) {
                            /* Data have been received */
                            /* Show image */
                            BitmapFactory.Options imageOption = new BitmapFactory.Options();
                            imageOption.inJustDecodeBounds = true;
                            BitmapFactory.decodeResource(mainActivity.getResources(), R.id.display_image, imageOption);
                            imageOption.inSampleSize = calculateInSampleSize (imageOption, 550, 435) ;
                            imageOption.inJustDecodeBounds = false;
                            bitmapImageToDisplay = BitmapFactory.decodeByteArray(dataBuffer, 23, decodeData.imageSize, imageOption);

                            if (bitmapImageToDisplay != null) {
                                mainActivity.runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {
                                        //try to display to image
                                        displayedImage.setImageBitmap(bitmapImageToDisplay);
                                    }
                                });
                            }
                        }
                    }
                    SystemClock.sleep(300);
                    bitmapImageToDisplay = null ;
                }
            }
            streamSocket.close();
            mReceivingStop = true;

            mainActivity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(mainActivity, "Finished", Toast.LENGTH_LONG).show();
                }
            });
        } catch (IOException e) {
            e.printStackTrace();
            StringBuilder eMsg = new StringBuilder();
            eMsg.append("Something wrong: " + e.getMessage());
            final String eMessage=eMsg.toString();
            // final String eMsg = "Something wrong: " + e.getMessage();

            mainActivity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(mainActivity, eMessage, Toast.LENGTH_LONG).show();
                }
            });
        } finally {
            if(streamSocket != null){
                try {
                    streamSocket.close();
                    mReceivingStop = true ;
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

日志输出：

GC_FOR_ALLOC freed 1307K, 27% free 13676K/18596K, paused 34ms, total 34ms
D/dalvikvm: GC_FOR_ALLOC freed 1306K, 27% free 13676K/18596K, paused 8ms, total 8ms
D/skia: --- SkImageDecoder::Factory returned null
D/skia: --- SkImageDecoder::Factory returned null
D/dalvikvm: GC_FOR_ALLOC freed 1607K, 29% free 13376K/18596K, paused 24ms, total 24ms
D/skia: --- SkImageDecoder::Factory returned null
D/dalvikvm: GC_FOR_ALLOC freed 1255K, 27% free 13728K/18596K, paused 9ms, total 9ms
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1 回答 1

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在 Android 上加载位图是一个庞大且相当复杂的主题。这就是为什么我建议使用经过验证的库之一来为您处理它；如Glide、Picasso或Fresco。这些库将为您处理加载位图带来的许多陷阱；包括内存限制、缓存和线程。

如果你真的想一个人去，你将不得不自己面对这些问题。如果位图无法正确解码，这就是方法吐出的内容，这可能是由许多问题引起的SkImageDecoder::Factory returned null。BitmapFactory.decode...我不知道究竟是什么导致了这种情况，但我确实在您的代码中看到了一些问题。

首先，您将MainActivity传入Thread，这只是自找麻烦。相反，您应该只需要将ImageViewinto 传递给Thread. 并确保您使用 a WeakReference，否则您可能会泄露您的Context:

WeakReference<ImageView> mDisplayedImageView;

SocketServerStreamDataThread(Socket socket, ImageView imageView) {
    mDisplayedImageView = new WeakReference<>(imageView);
    ...
}

接下来，您正在使用可绘制资源来解码 的边界Bitmap，但随后您尝试Bitmap从Socket连接中获取 a。相反，您应该使用以下方法解码边界InputStream：

BufferedInputStream inBounds = new BufferedInputStream(streamSocket.getInputStream());

BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(inBounds, null, options);

options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

inBounds.close();

而且你不需要一个单独的DecodeData类，因为BitmapFactory也有一个解码流的方法：

options.inJustDecodeBounds = false;

BufferedInputStream in = new BufferedInputStream(streamSocket.getInputStream());

Bitmap bitmap = BitmapFactory.decodeStream(in, null, options);

in.close();

最后，如果您正在使用Thread.sleep()或SystemClock.sleep()克服一些障碍，您可能应该重新考虑您的解决方案。这些只是我快速浏览时注意到的问题。如果您真的想在没有库帮助的情况下继续，我建议您对如何有效地加载位图进行更多研究；一个好的起点是文档。

于 2016-09-27T15:23:49.413 回答