将位图保存到外部存储器

Question

我正在将GIF保存到外部存储器中，在我的代码中我从Drawable获取GIF并且我能够将其保存到外部存储器Fine.But任何人都可以帮我从GifImageView的Bitmap保存GIF。 / p>

  protected void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState != null)
        fileName = savedInstanceState.getString("fileName");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    gif = (GifImageView) findViewById(R.id.ggg);
 save.setOnClickListener(new saveclick());
 }


      class saveclick implements Button.OnClickListener {
    @Override
    public void onClick(View v) {

      saveGIF();
                         }
                             }

               private void saveGIF()
{
    try
    {
        File file = new 

          File(Environment.getExternalStoragePublicDirectory
                                (Environment.DIRECTORY_DOWNLOADS), "shared_gif_shai" + 
                  System.currentTimeMillis() +  ".gif");

        long startTime = System.currentTimeMillis();


       // InputStream is = new BufferedInputStream(new 
        FileInputStream("source.bitmap"));
        InputStream is =getResources().openRawResource(+R.drawable.aa);

        BufferedInputStream bis = new BufferedInputStream(is);
        //bitmap = BitmapFactory.decodeStream(bis);


        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        //Log.d(TAG, "on do in background, create buffered array output 
        stream");

        byte[] img = new byte[1024];

        int current = 0;


        while ((current = bis.read()) != -1) {
            baos.write(current);
        }



        FileOutputStream fos = new FileOutputStream(file);
        fos.write(baos.toByteArray());


        fos.flush();

        fos.close();
        is.close();

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

此代码中的InputStream是从drawable获取GIF，有没有办法将位图转换为inputStream？非常感谢。