java 生成透明背景图片

        //开始绘图
         graphics2d.setBackground(Color.WHITE);
         graphics2d.clearRect(0, 0, width, height);                 
        graphics2d.setPaint(new Color(backgroundcolorR, backgroundcolorG, backgroundcolorB,backgroundcolorA));      //设置背景颜色
        graphics2d.fillRect(0, 0, width, height);  //填充颜色

        //设置透明  start  
        bufferedImage = graphics2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);  
        graphics2d=bufferedImage.createGraphics();  
        //设置透明  end