给图片添加水印

/**
 * @param iconPath    水印图片路径
 * @param sourceBytes 源文件字节流
 * @param position    水印位置
 * @param degree      便宜度
 * @return
 */
public static byte[] markImageByIcon(String iconPath, byte[] sourceBytes, Integer position, Integer degree) {
    byte[] targetByte = null;
    ByteArrayOutputStream os = null;
    try {
        Image srcImg = ImageIO.read(new ByteArrayInputStream(sourceBytes));
        BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),
                srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);
        // 1、得到画笔对象
        Graphics2D g = buffImg.createGraphics();
        // 2、设置对线段的锯齿状边缘处理
        g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g.drawImage(srcImg.getScaledInstance(srcImg.getWidth(null),
                srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0,
                null);
        // 3、设置水印旋转
        if (null != degree) {
            g.rotate(Math.toRadians(degree),
                    (double) buffImg.getWidth() / 2,
                    (double) buffImg.getHeight() / 2);
        }
        // 4、水印图片的路径 水印图片一般为gif或者png的，这样可设置透明度
        ImageIcon imgIcon = new ImageIcon(iconPath);
        // 5、得到Image对象。
        Image img = imgIcon.getImage();

        ImagePosition imagePosition;
        if (null != position) {
            imagePosition = getPosition(position, srcImg.getWidth(null), srcImg.getHeight(null),
                    img.getWidth(null), img.getHeight(null));
        } else {
            imagePosition = new ImagePosition(positionWidth, positionHeight);
        }

        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,
                alpha));
        // 6、水印图片的位置
        g.drawImage(img, imagePosition.getWidth(), imagePosition.getHeight(), null);
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
        // 7、释放资源
        g.dispose();
        // 8、生成图片
        os = new ByteArrayOutputStream();
        ImageIO.write(buffImg, "JPG", os);
        targetByte = os.toByteArray();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (null != os) {
                os.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    return targetByte;
}

private static ImagePosition getPosition(int position, int width, int height, int icWidth, int icHeight) {
    int x = 0;
    int y = 0;
    switch (position) {
        case 1:
            //位置 0，0
            break;
        case 2:
            x = (width / 2) - (icWidth / 2);
            break;
        case 3:
            x = width - icWidth;
            break;
        case 4:
            y = (height / 2) - (icHeight / 2);
            break;
        case 5:
            x = (width / 2) - (icWidth / 2);
            y = (height / 2) - (icHeight / 2);
            break;
        case 6:
            x = width - icWidth;
            y = (height / 2) - (icHeight / 2);
            break;
        case 7:
            y = height - icHeight;
            break;
        case 8:
            x = (width / 2) - (icWidth / 2);
            y = height - icHeight;
        case 9:
            x = width - icWidth;
            y = height - icHeight;
            break;
        default:
    }
    return new ImagePosition(x, y);
}