Drawable, Bitmap和byte[]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; 
            } 
      }