java对PNG图片圆角处理 保持PNG透明背景

http://my.oschina.net/u/2358721/blog/634042

/*
* 圆角处理
* @param BufferedImage
* @param cornerRadius
* */
public static String makeRoundedCorner(String srcImageFile, String result, String type, int cornerRadius) {
    try {
        BufferedImage image = ImageIO.read(new File(srcImageFile));
        int w = image.getWidth();
        int h = image.getHeight();
        BufferedImage output = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2 = output.createGraphics();
        output = g2.getDeviceConfiguration().createCompatibleImage(w, h, Transparency.TRANSLUCENT);
        g2.dispose();
        g2 = output.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.fillRoundRect(0, 0,w, h, cornerRadius, cornerRadius);
        g2.setComposite(AlphaComposite.SrcIn);
        g2.drawImage(image, 0, 0, w, h, null);
        g2.dispose();
        ImageIO.write(output, type, new File(result));
        return result;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}