图片加水印

package com.huawei.filter;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.imageio.ImageIO;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class FilterServlet extends HttpServlet implements Filter {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

 }

 public void doFilter(ServletRequest arg0, ServletResponse arg1,
   FilterChain arg2) throws IOException, ServletException {
  
  //得到图片的文件名
  HttpServletRequest request = (HttpServletRequest) arg0;
  HttpServletResponse response = (HttpServletResponse) arg1;
  //文件的相对路径
  String filename = request.getServletPath();
  //变成绝对路径
  String truepath = request.getRealPath(filename);
  //用io流读取文件处理加上水印输出
  FileInputStream sFile = new FileInputStream(truepath);
  //创建一个image对象并以源图片数据流填充
  Image src = ImageIO.read(sFile);
  //得到源图像宽度
  int width = src.getWidth(null);
  //得到源图像长度
  int height = src.getHeight(null);
  //创建一个bufferedimage来作为图像操作容器
  BufferedImage image = new BufferedImage(width, height,
    BufferedImage.TYPE_INT_RGB);
  //创建一个绘图环境来进行绘制图像
  Graphics g = image.getGraphics();
  //将原图像数据流载入这个bufferedimage
  g.drawImage(src, 0, 0, width, height, null);
  //设置文本字体
  g.setFont(new Font("Times New Roman", Font.PLAIN, 30));
  //字符水印
  String rand = "http://www.sina.com";
  //设定文本颜色
  g.setColor(Color.red);
  //向bufferedimage 写入文本字符
  g.drawString(rand, width - 300, height - 90);
  //使更改生效
  g.dispose();

  //创建输出文件流
  JPEGImageEncoder encodera = JPEGCodec.createJPEGEncoder(response
    .getOutputStream());
  //对这个bufferedimage进行jpeg编码
  encodera.encode(image);
  //关闭输出文件流
  response.getOutputStream().close();
  arg2.doFilter(arg0, arg1);

 }

 public void init(FilterConfig arg0) throws ServletException {
  // TODO Auto-generated method stub

 }

}