android – decodeStream返回null
作者:互联网
我正在尝试采用bitmap resizing教程 – 唯一的区别是我使用decodeStream而不是decodeResource.这很奇怪,但是没有任何操作的decodeStream给了我一个位图obj,但是当我通过decodeSampledBitmapFromStream时它会因某种原因返回null.
我如何解决它 ?
这是我使用的代码:
protected Handler _onPromoBlocksLoad = new Handler() {
@Override
public void dispatchMessage(Message msg) {
PromoBlocksContainer c = (PromoBlocksContainer) _promoBlocksFactory.getResponse();
HttpRequest request = new HttpRequest(c.getPromoBlocks().get(0).getSmallThumbnail());
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
InputStream stream;
ImageView v = (ImageView) findViewById(R.id.banner);
try {
stream = request.getStream();
//v.setImageBitmap(BitmapFactory.decodeStream(stream)); Works fine
Bitmap img = decodeSampledBitmapFromStream(stream, v.getWidth(), v.getHeight());
v.setImageBitmap(img);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
};
public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float)height / (float)reqHeight);
} else {
inSampleSize = Math.round((float)width / (float)reqWidth);
}
}
return inSampleSize;
}
public static Bitmap decodeSampledBitmapFromStream(InputStream res, int reqWidth, int reqHeight) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(res, null, options);
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
options.inJustDecodeBounds = false;
Bitmap img = BitmapFactory.decodeStream(res, null, options); // Gives null
return img;
}
解决方法:
问题是,一旦你使用了来自HttpUrlConnection的InputStream,你就不能再回放并再次使用相同的InputStream.因此,您必须为图像的实际采样创建新的InputStream.否则我们必须中止http请求.
request.abort();
标签:android,bitmap,android-image 来源: https://codeday.me/bug/20190716/1480851.html