BitMap、Drawable、inputStream及byte[] 互转

（1） BitMap to inputStream：
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
InputStream isBm = new ByteArrayInputStream(baos .toByteArray());

（2）BitMap to byte[]：
Bitmap defaultIcon = BitmapFactory.decodeStream(in);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
defaultIcon.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] bitmapdata = stream.toByteArray();
（3）Drawable to byte[]：
Drawable d; // the drawable (Captain Obvious, to the rescue!!!)
Bitmap bitmap = ((BitmapDrawable)d).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
defaultIcon.compress(Bitmap.CompressFormat.JPEG, 100, bitmap);
byte[] bitmapdata = stream.toByteArray();

（4）byte[] to Bitmap ：
Bitmap bitmap =BitmapFactory.decodeByteArray(byte[], 0,byte[].length);