android --- Drawable、Bitmap、byte[]之间的转换

android在处理一写图片资源的时候，会进行一些类型的转换，现在有空整理一下：

1、Drawable → Bitmap
Java代码
public static Bitmap drawableToBitmap(Drawable drawable) {

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);
//canvas.setBitmap(bitmap);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
drawable.draw(canvas);
return bitmap;
}

2、从资源中获取Bitmap

Java代码
Resources res=getResources();

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

3、Bitmap → byte[]

Java代码
private byte[] Bitmap2Bytes(Bitmap bm){
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}

4、 byte[] → Bitmap
Java代码
private Bitmap Bytes2Bimap(byte[] b){
if(b.length!=0){
return BitmapFactory.decodeByteArray(b, 0, b.length);
}
else {
return null;
}
}