当图片过大，或图片数量较多时使用BitmapFactory解码图片会出java.lang.OutOfMemoryError: bitmap size exceeds VM budget，要想正常使用则需分配更少的内存，具体的解决办法是修改采样值BitmapFactory.Options.inSampleSize，例如：

BitmapFactory.Options opts = new BitmapFactory.Options();opts.inSampleSize = 4;Bitmap bitmap = BitmapFactory.decodeFile(imageFile, opts);

如何设置恰当的inSampleSize

设置恰当的inSampleSize是解决该问题的关键之一。BitmapFactory.Options提供了另一个成员inJustDecodeBounds。

BitmapFactory.Options opts = new BitmapFactory.Options();opts.inJustDecodeBounds = true;Bitmap bitmap = BitmapFactory.decodeFile(imageFile, opts);

设置inJustDecodeBounds为true后，decodeFile并不分配空间，但可计算出原始图片的长度和宽度，即opts.width和opts.height。有了这两个参数，再通过一定的算法，即可得到一个恰当的inSampleSize。

查看Android源码，Android提供了一种动态计算的方法。

public static int computeSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {int initialSize = computeInitialSampleSize(options, minSideLength,maxNumOfPixels);

int roundedSize;if (initialSize <= 8 ) {        roundedSize = 1;while (roundedSize < initialSize) {            roundedSize <<= 1;        }    } else {        roundedSize = (initialSize + 7) / 8 * 8;    }

return roundedSize;}

private static int computeInitialSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {double w = options.outWidth;double h = options.outHeight;

int lowerBound = (maxNumOfPixels == -1) ? 1 :            (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));int upperBound = (minSideLength == -1) ? 128 :            (int) Math.min(Math.floor(w / minSideLength),            Math.floor(h / minSideLength));

if (upperBound < lowerBound) {// return the larger one when there is no overlapping zone.        return lowerBound;    }

if ((maxNumOfPixels == -1) &&            (minSideLength == -1)) {return 1;    } else if (minSideLength == -1) {return lowerBound;    } else {return upperBound;    }}

使用该算法，就可动态计算出图片的inSampleSize。

BitmapFactory.Options opts = new BitmapFactory.Options();opts.inJustDecodeBounds = true;BitmapFactory.decodeFile(imageFile, opts);

opts.inSampleSize = computeSampleSize(opts, -1, 128*128);opts.inJustDecodeBounds = false;try {    Bitmap bmp = BitmapFactory.decodeFile(imageFile, opts);    imageView.setImageBitmap(bmp);    } catch (OutOfMemoryError err) {}

另外，可以通过Bitmap.recycle()方法来释放位图所占的空间，当然前提是位图没有被使用。