Bitmap，byte流，drawable之相互转换

刚开始学习android，以前学习J2me的时候也碰到过类似的问题，现在看到有同学总结过了，地址为：http://www.iteye.com/topic/642128 
   这里全文摘抄，以备学习：） 
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;  
            }  
      }