在Android程序中往往需要对图片进行处理，也就是将图片解析为字节数组，读取字节数组转换成图片，图片Bitmap 和Drawable 的转换，下边写了3个方法去实现这写转换

//bitmap 和 drawable的转换

public static Bitmap drawableToBitmap(Drawable drawable){
    int width = drawable.getIntrinsicWidth();
    int height = drawable.getIntrinsicHeight();
    Bitmap bitmap = Bitmap.createBitmap(width, height,
    drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0,0,width,height);
    drawable.draw(canvas);
    return bitmap;
    }

//bitmap和byte[]的转换

public byte[] getBitmapByte(Bitmap bitmap){
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);
    try {
        out.flush();
        out.close();
    } catch (IOException e) {
        e.printStackTrace();
        }
    return out.toByteArray();
    }

public Bitmap getBitmapFromByte(byte[] temp){
    if(temp != null){
        Bitmap bitmap = BitmapFactory.decodeByteArray(temp, 0, temp.length);
        return bitmap;
    }else{
        return null;
        }
    }