java如何给图片加水印？

这篇文章给大家分享的是java给图片加水印的方法，相信大部分人都还没学会这个技能，为了让大家更加了解，给大家总结了以下内容，话不多说，一起往下看吧。

具体代码：

 // 水印透明度    private static float alpha = 0.5f;           /**     * 给图片添加水印图片、可设置水印图片旋转角度     *     * @param iconPath   水印图片路径     * @param srcImgPath 源图片路径     * @param location   水印图片位置     * @param degree     水印图片旋转角度     */    public static void markImageByIcon(HttpServletRequest request, HttpServletResponse response,                                       String iconPath, String srcImgPath, String location, Integer degree) {        OutputStream os = null;        try {            Image srcImg = ImageIO.read(new File(srcImgPath));            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),                    srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);            // 得到画笔对象            Graphics2D g = buffImg.createGraphics();            // 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);            // 设置水印旋转角度（默认对角线角度）            if (null != degree) {                g.rotate(Math.toRadians(degree), (double) buffImg.getWidth() / 2, (double) buffImg.getHeight() / 2);            } else {                //根据三角形相关定理，计算对角线角度                double lengthOfDiagonal = Math.sqrt(buffImg.getWidth() * buffImg.getWidth() + buffImg.getHeight() * buffImg.getHeight());                double v = (Math.pow(buffImg.getWidth(), 2) + Math.pow(lengthOfDiagonal, 2) - Math.pow(buffImg.getHeight(), 2)) / (2 * buffImg.getWidth() * lengthOfDiagonal);                double acos = Math.acos(v);                double myDegree = Math.toDegrees(acos);                g.rotate(-Math.toRadians(myDegree), (double) buffImg.getWidth() / 2, (double) buffImg.getHeight() / 2);            }            // 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);            Image img = imgIcon.getImage();            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,                    alpha));            // 水印图片的位置            int x = 0, y = 0;            if (StringUtils.equals(location, "left-top")) {                x = 30;                y = 30;            } else if (StringUtils.equals(location, "right-top")) {                x = buffImg.getWidth() - img.getWidth(null) - 30;                y = 30;            } else if (StringUtils.equals(location, "left-bottom")) {                x += 30;                y = buffImg.getHeight() - img.getHeight(null) - 30;            } else if (StringUtils.equals(location, "right-bottom")) {                x = buffImg.getWidth() - img.getWidth(null) - 30;                y = buffImg.getHeight() - img.getHeight(null) - 30;            } else {                x = (buffImg.getWidth() - img.getWidth(null)) / 2;                y = (buffImg.getHeight() - img.getHeight(null)) / 2;            }            g.drawImage(img, x, y, null);            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));            g.dispose();            // os = new FileOutputStream(targerPath);            os = response.getOutputStream();            ImageIO.write(buffImg, "JPG", os);        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if (null != os)                    os.close();            } catch (Exception e) {                e.printStackTrace();            }        }    }

smbfile时也可以写成这样：

// 展示时 添加水印        public void showRemarkImage(String filePath, String iconPath, HttpServletRequest request, HttpServletResponse response) {                InputStream is = null;                OutputStream os = null;                ByteArrayOutputStream out = new ByteArrayOutputStream();                  try {                        SmbFile smbFile = new SmbFile(filePath);                        is = smbFile.getInputStream();                        os = response.getOutputStream();                                                Image srcImg = ImageIO.read(is);            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),                    srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);            // 得到画笔对象            Graphics2D g = buffImg.createGraphics();            // 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);                                 // 旋转角度处理（根据三角形相关定理，计算对角线角度）//            double lengthOfDiagonal = Math.sqrt(buffImg.getWidth() * buffImg.getWidth() + buffImg.getHeight() * buffImg.getHeight());//            double v = (Math.pow(buffImg.getWidth(), 2) + Math.pow(lengthOfDiagonal, 2) - Math.pow(buffImg.getHeight(), 2)) / (2 * buffImg.getWidth() * lengthOfDiagonal);//            double acos = Math.acos(v);//            double myDegree = Math.toDegrees(acos);//            g.rotate(-Math.toRadians(myDegree), (double) buffImg.getWidth() / 2, (double) buffImg.getHeight() / 2);                                  // 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);            Image img = imgIcon.getImage();            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));            // 水印图片居中            int x = 0, y = 0;                   x = (buffImg.getWidth() - img.getWidth(null)) / 2;            y = (buffImg.getHeight() - img.getHeight(null)) / 2;                      g.drawImage(img, x, y, null);            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));            g.dispose();                                       ImageIO.write(buffImg, "png", out);                 byte[] b = out.toByteArray();                        response.addHeader("Content-Length", String.valueOf(b.length));                                       os.write(b, 0, b.length);                        os.flush();                                          } catch (Exception e) {                        LogUtil.error("附件下载失败，时间：" + DateUtil.formatToDateTimeText(new Date()) + "原因：" + e.getMessage());//                      throw new ApplicationException("文件读取失败：" + e.getMessage(), e);                } finally {                        IOUtils.closeQuietly(is);                        IOUtils.closeQuietly(os);                        IOUtils.closeQuietly(out);                }        }

以上就是java给图片加水印的方法，代码详细清楚，如果在日常工作遇到这个问题，希望你能通过这篇文章解决问题。如果想了解更多相关内容，欢迎关注行业资讯频道！