Question

我想从网址加载巨大的图片并在我的设备上显示。我这样做了this帖子。

在该示例中，他们使用原生drawable，但我想从服务器获取图像。

我正在使用此代码

 private void getBitmap(ImageView imageView,final String url){

        mBitmapOptions = new BitmapFactory.Options();
        mBitmapOptions.inJustDecodeBounds = true;
        URL mUrl = null;
        InputStream is= null;
        try {
            mUrl = new URL(url);
            is = mUrl.openStream();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
//        BitmapFactory.decodeStream(is,null,mBitmapOptions);

        mCurrentBitmap = Bitmap.createBitmap(mBitmapOptions.outWidth,
                mBitmapOptions.outHeight, Bitmap.Config.ARGB_8888);
        mBitmapOptions.inJustDecodeBounds = false;
        mBitmapOptions.inBitmap = mCurrentBitmap;
        mBitmapOptions.inSampleSize = 1;
        BitmapFactory.decodeStream(is,null,mBitmapOptions);
        imageView.setImageBitmap(mCurrentBitmap);
//        Bitmap croppedBitmap=Bitmap.createBitmap(Bitmap.createBitmap(mCurrentBitmap, 0, mCurrentBitmap.getHeight()/2, mCurrentBitmap.getWidth(), mCurrentBitmap.getHeight()/2));
//        imageView.setImageBitmap(croppedBitmap);
    }

我想在这里从url获取图片并调整其大小，但我有一个例外。

java.lang.IllegalArgumentException: width and height must be > 0

我在这里做错了什么？或者你能建议我更好的回答吗？

Answer 1

我会使用Picasso，那么你想要实现的就是这样简单：

Picasso.with(context).load(url).resize(50, 50).into(imageView)

http://square.github.io/picasso/

Answer 2

您因以下原因而获得例外：

// BitmapFactory.decodeStream(is,null,mBitmapOptions);

尝试调用时没有设置mBitmapOptions：

mCurrentBitmap = Bitmap.createBitmap(mBitmapOptions.outWidth, mBitmapOptions.outHeight, Bitmap.Config.ARGB_8888);

请仔细查看此问题的答案，以进一步优化您的代码：Getting the size of an image inputstream

Answer 3

我根据http://developer.android.com/training/displaying-bitmaps/load-bitmap.html教程开发了一个解决方案。这是我的代码。棘手的部分包括使用字节数组来存储图像数据（因为不幸markSupported（）不适用于connection.getInputStream()）。

    public static Bitmap getBitmapFromURL(final String imageUrl, final Options options, int reqWidth, int reqHeight) {
    try {
        URL url = new URL(imageUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.connect();
        final InputStream input = connection.getInputStream();
        // using byte array to prevent open 2 times a stream
        final BufferedInputStream bis = new BufferedInputStream(input, 4*1024);
        ByteArrayBuffer baf = new ByteArrayBuffer(50);
        int current = 0;
        while ((current = bis.read()) != -1) {
            baf.append((byte)current);
        }
        bis.close();
        byte[] imageData = baf.toByteArray();
        if(options != null){
            // First decode with inJustDecodeBounds=true to check dimensions
            final BitmapFactory.Options optionsSize = new BitmapFactory.Options();
            optionsSize.inJustDecodeBounds = true;


            BitmapFactory.decodeByteArray(imageData, 0, imageData.length, optionsSize);

            // Calculate inSampleSize
            options.inSampleSize = calculateInSampleSize(optionsSize, reqWidth, reqHeight);

            // Decode bitmap with inSampleSize set
            optionsSize.inJustDecodeBounds = false;

        }
        Bitmap myBitmap = null;
        if(options == null){
            myBitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.length);
        }
        else{
            myBitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.length, options);
        }
        // close the stream;
        input.close();
        return myBitmap;
    } catch (Exception e) {
        return null;
    }
}

private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int halfHeight = height / 2;
        final int halfWidth = width / 2;

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while ((halfHeight / inSampleSize) > reqHeight
                && (halfWidth / inSampleSize) > reqWidth) {
            inSampleSize *= 2;
        }
    }

    return inSampleSize;
}

希望它会对你有所帮助。

从url加载大位图并调整其大小

3 个答案: