JSP验证码

  利用servlet生成验证码

/**
 * ValidateCodeImage调用RandomCode用来产生验证码
 */
package edu.hrbeu.cstcmis.servlet;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import edu.hrbeu.cstcmis.image.RandomCode;

public class ValidateCodeImage extends HttpServlet {
 public ValidateCodeImage() {
  super();
 }
 private static final long serialVersionUID = 1L;
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doPost(request,response);
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  response.setContentType("image/jpeg");
  response.setHeader("Pragram","NO-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
  RandomCode rc = new RandomCode();
  rc.getRandCode(request,response);
 }

}

/**
 * RandomCode生成图片验证码
 */
package edu.hrbeu.cstcmis.image;
import java.awt.Font;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletException;
import java.io.IOException;
public class RandomCode {
 //随机取得一个地址
 private synchronized Font getFonts(Random random){
  return new Font("Fixedsys",Font.CENTER_BASELINE,18);
 }
 //返回一个随机颜色
 private synchronized Color getRandColor(int fc,int bc,Random random){
  if(fc>255)fc=255;
  if(bc>255)bc=255;
  int r=fc+random.nextInt(bc-fc-6);
  int g=fc+random.nextInt(bc-fc-4);
  int b=fc+random.nextInt(bc-fc-8);
  return new Color(r,g,b);
 }
 //生成随机数图片
 public synchronized void getRandCode(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
  System.setProperty("java.awt.headless","true");
  HttpSession session=request.getSession();
  int width=80,height=26;//设置图片大小
  BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
  Graphics g=image.getGraphics();
  Random random=new Random();
  g.fillRect(0, 0, width, height);//设定边框
  g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
  g.setColor(getRandColor(111,133,random));
  for(int i=0;i<11;i++){
   int x=random.nextInt(width);
   int y=random.nextInt(height);
   int xl=random.nextInt(13);
   int yl=random.nextInt(15);
   g.drawLine(x, y, xl, yl);
  }
  g.setColor(getRandColor(130,150,random));
  //产生5个随机数
  String sRand="";
  for(int i=0;i<5;i++){
   sRand="";//此处必须出示化为空
   g.setFont(getFonts(random));
   g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
   String rand=String.valueOf(getRandomString(random.nextInt(36)));
   sRand+=rand;
   g.translate(random.nextInt(3),random.nextInt(3));
   g.drawString(sRand,13*i,16);
  }
  session.removeAttribute("Rand");
  session.setAttribute("Rand", sRand);
  g.dispose();
  ImageIO.write(image, "JPEG", response.getOutputStream());
 }
 private String getRandomString(int num) {
  String randString = "0123456789abcdefghijklmnopqrstuvwxyz";
  return String.valueOf(randString.charAt(num));
 }
}