如何正确旋转位图？

旋转位图我遇到了很多麻烦.下面的代码有效,但它比Galaxy Note 2手机附带的Gallery应用程序慢4-6倍.

码:

    File DirectoryFile = new File(Image_Path); 
    Bitmap bitmap = BitmapFactory.decodeFile(DirectoryFile.getAbsolutePath()); 



    String imagePATH = FileLocation + "test.jpg";
    final File newfile = new File(imagePATH);           

    FileOutputStream mFileOutputStream = null;
    try {                   
           mFileOutputStream = new FileOutputStream(newfile);
       } catch (FileNotFoundException e1) { }

        try {
        Bitmap RotatedBitmap =  RotateImage(imagePATH, bitmap);
        RotatedBitmap.compress(Bitmap.CompressFormat.JPEG, 100, mFileOutputStream);
        bitmap.recycle(); 
        RotatedBitmap.recycle();

        mFileOutputStream.flush();
        mFileOutputStream.close();

    } catch (IOException e) {
        e.printStackTrace();
    }

private Bitmap RotateImage(String filePath, Bitmap bitmap) throws IOException {
    ExifInterface exif = new ExifInterface(filePath);
    int exifOrientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
    int rotate = 0;
    switch (exifOrientation) {
    case ExifInterface.ORIENTATION_NORMAL: rotate = 0; break;               
    case ExifInterface.ORIENTATION_UNDEFINED: rotate = 90; break;                               
    case ExifInterface.ORIENTATION_ROTATE_90: rotate = 90; break; 
    case ExifInterface.ORIENTATION_ROTATE_180: rotate = 180; break;
    case ExifInterface.ORIENTATION_ROTATE_270: rotate = 270; break;
    }                 

    Matrix matrix = new Matrix();
    matrix.postRotate(rotate);
    //matrix.setRotate(rotate); is no difference ???
    return bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, false);
}

请有人请指导我这个吗？

如何让它像Gallery应用程序一样工作？