Android中通过代码修改bitmap的宽高

public Bitmap getNewBitmap(Bitmap bitmap, int newWidth ,int newHeight){
    // 获得图片的宽高.
    int width = bitmap.getWidth();
    int height = bitmap.getHeight();
    // 计算缩放比例.
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;
    // 取得想要缩放的matrix参数.
    Matrix matrix = new Matrix();
    matrix.postScale(scaleWidth, scaleHeight);
    // 得到新的图片.
    Bitmap newBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
    return newBitmap;
}