我要在Android的图库中保存Gif图像。 我已经尝试了很多次将gif保存到图库中，但是当我按下保存按钮时，它已下载但不是gif格式。我不知道是什么问题。

请帮助我解决这个问题

public void saveImageToExternal(String imgName,Bitmap bm) throws IOException {
        //Create Path to save Image
        File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES + "/savaimage1.gif"); //Creates app specific folder
        path.mkdirs();
        File imageFile = new File(path,imgName + ".gif");// Imagename.png

        Log.e("msg",imageFile.toString());

        FileOutputStream out = new FileOutputStream(imageFile);
        Toast.makeText(this,"save",Toast.LENGTH_SHORT).show();
        try {
             bm.compress(Bitmap.CompressFormat.PNG,100,out); // Compress Image

            out.flush();
            out.close();

            // Tell the media scanner about the new file so that it is
            // immediately available to the user.
            MediaScannerConnection.scanFile(Mainactivity.this,new String[]{imageFile.getabsolutePath()},null,new MediaScannerConnection.OnScanCompletedListener() {
                public void onScanCompleted(String path,Uri uri) {
                    Log.i("ExternalStorage","Scanned " + path + ":");
                    Log.i("ExternalStorage","-> uri=" + uri);
                }
            });
        } catch (Exception e) {
            throw new IOException();
        }
    }