Android Drawable、Bitmap、byte[]之间

1. byte[ ] 转 Bitmap

BitmapFactory.decodeByteArray(byte, 0, byte.length)

2. Bitmap 转 byte[ ]

ByteArrayOutputStream baos = new ByteArrayOutputStream();  
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);  

3. Bitmap 转 Drawable

Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.pic); 

4. Drawable 转 Bitmap

if (drawable instanceof BitmapDrawable) {
       return ((BitmapDrawable) drawable).getBitmap();
} else if (drawable instanceof NinePatchDrawable) {
      Bitmap bitmap = Bitmap
         .createBitmap(
         drawable.getIntrinsicWidth(),
         drawable.getIntrinsicHeight(),
         drawable.getOpacity() != PixelFormat.OPAQUE ? 
         Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
      Canvas canvas = new Canvas(bitmap);
      drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
      drawable.getIntrinsicHeight());
      drawable.draw(canvas);
      return bitmap;
} else {
      return null;
}