java图片验证码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class ImageRandom extends HttpServlet {
 /**
  * Constructor of the object.
  */
 public ImageRandom() {
  super();
 }
 public void processRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
  response.setContentType("image/jpeg");
  response.setHeader("Pragma","No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
  HttpSession session=request.getSession();
  // 在内存中创建图象
  int width=60, height=20;
  BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
  // 获取图形上下文
  Graphics graphics = image.getGraphics();
  //生成随机类
  Random random = new Random();
  // 设定背景色
  //graphics.setColor(this.getRandColor(100,150));
  graphics.setColor(Color.gray);
  graphics.clipRect(0, 0, width, height);
  //设定字体
  graphics.setFont(new Font("Times New Roman",Font.PLAIN,18));
  //画边框
  //graphics.setColor(new Color());
  //graphics.drawRect(0,0,width-1,height-1);
  
  // 随机产生50条干扰线，使图象中的认证码不易被其它程序探测到
  graphics.setColor(getRandColor(100,200));
  for (int i=0;i<50;i++) {
   int x = ran