如何给上传图片增加水印

下面是加水印的函数，直接在上传图片的地方调用就好了，两个参数分别是File和String。

/** * 加水印 * @param ifile */public void addWaterMark(File ifile,String url){ try {String waterMarkContent="论坛报名专用"; Image srcImg = ImageIO.read(ifile);int srcImgWidth = srcImg.getWidth(null);int srcImgHeight = srcImg.getHeight(null); // 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(new Color(255,0,0)); //根据图片的背景设置水印颜色g.setFont(new Font("宋体",Font.PLAIN,50));              //设置字体//设置水印的坐标int x = 50;//srcImgWidth - 2*getWatermarkLength(waterMarkContent, g);  int y = 100;//srcImgHeight - 2*getWatermarkLength(waterMarkContent, g);  g.drawString(waterMarkContent, x, y);  //画出水印g.dispose();  // 输出图片  FileOutputStream outImgStream = new FileOutputStream(url);  ImageIO.write(bufImg, "jpg", outImgStream);System.out.println("添加水印完成");  outImgStream.flush();  outImgStream.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}  }private int getWatermarkLength(String waterMarkContent, Graphics2D g) { return g.getFontMetrics(g.getFont()).charsWidth(waterMarkContent.toCharArray(), 0, waterMarkContent.length());  }