Java实现图片生成水印

要先得到缓存图片对象
3个工具类：
BufferedImage，Graphics2D，JPEGImageEncoder

文字水印： // 读取原图片信息
File srcImgFile = new File(srcImgPath);//得到文件
Image srcImg = ImageIO.read(srcImgFile);//文件转化为图片
int srcImgWidth = srcImg.getWidth(null);//获取图片的宽
int srcImgHeight = srcImg.getHeight(null);//获取图片的高
// 加水印
BufferedImage bufImg = new BufferedImage(srcImgWidth, srcImgHeight, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bufImg.createGraphics();
g.drawImage(srcImg, 0, 0, srcImgWidth, srcImgHeight, null);
g.setColor(markContentColor); //根据图片的背景设置水印颜色
g.setFont(font); //设置字体

        //设置水印的坐标
        int x = srcImgWidth - 2*getWatermarkLength(waterMarkContent, g);  
        int y = srcImgHeight - 2*getWatermarkLength(waterMarkContent, g);  
        g.drawString(waterMarkContent, x, y);  //画出水印
        g.dispose();  
        // 输出图片  
        FileOutputStream outImgStream = new FileOutputStream(tarImgPath);  
        ImageIO.write(bufImg, "jpg", outImgStream);
        System.out.println("添加水印完成");  
        outImgStream.flush();  
        outImgStream.close();  

图片水印：/**

• 给图片添加水印、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 targerPath 目标图片路径

• @param degree 水印图片旋转角度
  */
  public static void markImageByIcon(String iconPath, String srcImgPath,
  String targerPath, 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   
      // Graphics g= buffImg.getGraphics();   
      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);   
  
      if (null != degree) {   
          // 设置水印旋转   
          g.rotate(Math.toRadians(degree),   
                  (double) buffImg.getWidth() / 2, (double) buffImg   
                          .getHeight() / 2);   
      }   
  
      // 水印图象的路径 水印一般为gif或者png的，这样可设置透明度   
      ImageIcon imgIcon = new ImageIcon(iconPath);   
  
      // 得到Image对象。   
      Image img = imgIcon.getImage();   
  
      float alpha = 0.5f; // 透明度   
      g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,   
              alpha));   
  
      // 表示水印图片的位置   
      g.drawImage(img, 150, 300, null);   
  
      g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));   
  
      g.dispose();   
  
      os = new FileOutputStream(targerPath);   
  
      // 生成图片   
      ImageIO.write(buffImg, "JPG", os);   
  
      System.out.println("图片完成添加Icon印章。。。。。。");   
  } catch (Exception e) {   
      e.printStackTrace();   
  } finally {   
      try {   
          if (null != os)   
              os.close();   
      } catch (Exception e) {   
          e.printStackTrace();   
      }   
  }   

  }