java实现一张透明背景的图片，添加图片水印

public static void createWaterMarkByIcon(File srcImageFile, File logoImageFile,
                                      File outputImageFile, double degree) {

        OutputStream os = null;
        try {
            Image srcImg = ImageIO.read(srcImageFile);

            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),
                    srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);

            Graphics2D graphics = buffImg.createGraphics();

            buffImg = graphics.getDeviceConfiguration().createCompatibleImage(srcImg.getWidth(null), srcImg.getWidth(null), Transparency.TRANSLUCENT);
            graphics = buffImg.createGraphics();
//            graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);

            int imgWidth = srcImg.getWidth(null);
            int imgHeight = srcImg.getHeight(null);

            graphics.drawImage(srcImg.getScaledInstance(srcImg.getWidth(null),
                    srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0, null);

            ImageIcon logoImgIcon = new ImageIcon(ImageIO.read(logoImageFile));
            Image logoImg = logoImgIcon.getImage();

            //旋转
            if (degree>0) {
                graphics.rotate(Math.toRadians(degree),
                        (double) buffImg.getWidth() / 2,
                        (double) buffImg.getWidth() / 2);
            }

            float alpha = 0.7f; // 透明度
            graphics.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));

            //水印 的位置
            int logoWidth = imgWidth/4;
            int logoHeight = logoWidth*17/20;

            graphics.drawImage(logoImg, buffImg.getWidth()-logoWidth, buffImg.getHeight()-logoHeight,logoWidth,logoHeight, null);
//            graphics.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
            graphics.dispose();

            os = new FileOutputStream(outputImageFile);
            // 生成图片
            ImageIO.write(buffImg, "PNG", os);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != os)
                    os.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

水印位置根据自己实际情况调整。
参考文档：
https://blog.csdn.net/gingerredjade/article/details/53193014