我开发了以下类来接收带有标头（22字节）的图像首先我解码标头以检查图像的正确性然后我解码图像但是并非所有图像都被解码，有时它会返回SkImageDecoder::Factory returned null。我正在使用this Android教程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();
}
}
}
}
}
Logcat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
答案 0 :(得分：0)
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一个经过验证的库来为您处理它;例如Glide，Picasso或Fresco。这些库将处理为您加载位图所带来的许多陷阱;包括内存约束，缓存和线程。
如果你真的想单独行动，你将不得不面对这些问题。如果位图无法正确解码，SkImageDecoder::Factory returned null方法会吐出BitmapFactory.decode...，这可能是由许多问题引起的。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许多问题。
首先，您将MainActivity传递给Thread，这只是在寻找麻烦。相反，您只需要将ImageView传递给Thread。并确保使用WeakReference，否则您可能会泄露Context：
WeakReference<ImageView> mDisplayedImageView;
SocketServerStreamDataThread(Socket socket, ImageView imageView) {
mDisplayedImageView = new WeakReference<>(imageView);
...
}
接下来，您使用可绘制资源来解码Bitmap的边界，但之后您尝试从Bitmap连接获取Socket。相反，您应该使用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();
并且您不需要单独的DecodeData类，因为BitmapFactory也有解码流的方法：
options.inJustDecodeBounds = false;
BufferedInputStream in = new BufferedInputStream(streamSocket.getInputStream());
Bitmap bitmap = BitmapFactory.decodeStream(in, null, options);
in.close();
最后，如果您使用Thread.sleep()或SystemClock.sleep()来克服某些障碍，您应该重新考虑您的解决方案。这些只是我在快速浏览时注意到的问题。如果你真的想在没有图书馆帮助的情况下继续下去，我建议你做一些有关如何有效加载位图的研究;一个好的起点是the documentation。