为图片

Question

我试图在我的网站上为图片添加水印。我想要它的工作方式是在下载或显示在其他网站上时显示水印。在我的网站上，我想在没有水印的情况下显示它。如果将水印放在上图片上，那将是非常棒的。例如，通过使用一些图片元数据或http标头，可以做到上面提到的吗？或者是不可能执行此操作，我应该通过在上传时添加页脚并将其隐藏来实现吗？

Answer 1

您可以参考以下链接：

为图片添加文字水印

static void addTextWatermark(String text, File sourceImageFile, File destImageFile) {
    try {
        BufferedImage sourceImage = ImageIO.read(sourceImageFile);
        Graphics2D g2d = (Graphics2D) sourceImage.getGraphics();

        // initializes necessary graphic properties
        AlphaComposite alphaChannel = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.1f);
        g2d.setComposite(alphaChannel);
        g2d.setColor(Color.BLUE);
        g2d.setFont(new Font("Arial", Font.BOLD, 64));
        FontMetrics fontMetrics = g2d.getFontMetrics();
        Rectangle2D rect = fontMetrics.getStringBounds(text, g2d);

        // calculates the coordinate where the String is painted
        int centerX = (sourceImage.getWidth() - (int) rect.getWidth()) / 2;
        int centerY = sourceImage.getHeight() / 2;

        // paints the textual watermark
        g2d.drawString(text, centerX, centerY);

        ImageIO.write(sourceImage, "png", destImageFile);
        g2d.dispose();

        System.out.println("The tex watermark is added to the image.");

    } catch (IOException ex) {
        System.err.println(ex);
    }
}

将图像水印添加到图像

static void addImageWatermark(File watermarkImageFile, File sourceImageFile, File destImageFile) {
    try {
        BufferedImage sourceImage = ImageIO.read(sourceImageFile);
        BufferedImage watermarkImage = ImageIO.read(watermarkImageFile);

        // initializes necessary graphic properties
        Graphics2D g2d = (Graphics2D) sourceImage.getGraphics();
        AlphaComposite alphaChannel = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.3f);
        g2d.setComposite(alphaChannel);

        // calculates the coordinate where the image is painted
        int topLeftX = (sourceImage.getWidth() - watermarkImage.getWidth()) / 2;
        int topLeftY = (sourceImage.getHeight() - watermarkImage.getHeight()) / 2;

        // paints the image watermark
        g2d.drawImage(watermarkImage, topLeftX, topLeftY, null);

        ImageIO.write(sourceImage, "png", destImageFile);
        g2d.dispose();

        System.out.println("The image watermark is added to the image.");

    } catch (IOException ex) {
        System.err.println(ex);
    }
}

http://www.codejava.net/java-se/graphics/adding-a-watermark-over-an-image-programmatically-using-java