Bitmap bitMap = BitmapFactory.decodeFile(path);
int width = bitMap.getWidth();
int height = bitMap.getHeight();
// 设置想要的大小
int newWidth = 500;
int newHeight = 400;
// 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 = Bitmap.createBitmap(bitMap, 0, 0, width, height, matrix, true);

Bitmap bm = BitmapFactory.decodeByteArray(imgdata, 0,imgdata.length);
Matrix matrix = new Matrix();
matrix.preRotate(270);
bm = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(),bm.getHeight(), matrix, true);