Android应用中因背景图片尺寸过大引发内存溢出问题的解决方案

public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
                                                             int reqWidth, int reqHeight) {
            // First decode with inJustDecodeBounds=true to check dimensions
            final BitmapFactory.Options optiOns= new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeResource(res, resId, options);
            // Calculate inSampleSize
            options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
            // Decode bitmap with inSampleSize set
            options.inJustDecodeBounds = false;
            return BitmapFactory.decodeResource(res, resId, options);
        }

        public 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) {
                // Calculate ratios of height and width to requested height and width
                final int heightRatio = Math.round((float) height / (float) reqHeight);
                final int widthRatio = Math.round((float) width / (float) reqWidth);

                // Choose the smallest ratio as inSampleSize value, this will guarantee
                // a final image with both dimensions larger than or equal to the
                // requested height and width.
                inSampleSize = heightRatio  heightRatio : widthRatio;
            }
            return inSampleSize;
        }