简单 验证码 功能

在贴代码之前首先简述一下验证验证码原理：随机获取验证码的值，把这个值存到session中，其作用可想而知就是要拿来跟前台数据作比较，通过Graphics将值进行模糊处理之后传到前台页面展示。

  1 package com.skss.util;
  2
  3
  4 import java.awt.Color;
  5 import java.awt.Font;
  6 import java.awt.Graphics;
  7 import java.awt.image.BufferedImage;
  8 import java.io.IOException;
  9 import java.util.Random;
 10
 11 import javax.imageio.ImageIO;
 12 import javax.servlet.ServletException;
 13 import javax.servlet.ServletOutputStream;
 14 import javax.servlet.http.HttpServlet;
 15 import javax.servlet.http.HttpServletRequest;
 16 import javax.servlet.http.HttpServletResponse;
 17 import javax.servlet.http.HttpSession;
 18
 19 @SuppressWarnings("serial")
 20 public class ValidateCodeServlet extends HttpServlet {
 21     char[] codeSequence={‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘, ‘G‘, ‘H‘, ‘I‘, ‘J‘,
 22             ‘K‘, ‘L‘, ‘M‘, ‘N‘, ‘O‘, ‘P‘, ‘Q‘, ‘R‘, ‘S‘, ‘T‘, ‘U‘, ‘V‘, ‘W‘,
 23             ‘X‘, ‘Y‘, ‘Z‘, ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘ };
 24     public ValidateCodeServlet() {
 25         super();
 26     }
 27
 28     public void destroy() {
 29         super.destroy();
 30     }
 31
 32     public void doGet(HttpServletRequest request, HttpServletResponse response)
 33             throws ServletException, IOException {
 34         this.doPost(request, response);
 35     }
 36
 37     public void doPost(HttpServletRequest request, HttpServletResponse response)
 38             throws ServletException, IOException {
 39         String params = request.getParameter("parame");
 40         response.setContentType("image/jpeg");
 41         response.setHeader("Pragma","No-cache");
 42         response.setHeader("Cache-Control","no-cache");
 43         response.setDateHeader("Expires", 0);
 44         HttpSession session=request.getSession();
 45         // 在内存中创建图象
 46         int width=60, height=20;
 47         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
 48         // 获取图形上下文
 49         Graphics g = image.getGraphics();
 50         //生成随机类
 51         Random random = new Random();
 52         // 设定背景色
 53         g.setColor(getRandColor(200,250));
 54         g.fillRect(0, 0, width, height);
 55         //设定字体
 56         g.setFont(new Font("Times New Roman",Font.PLAIN,18));
 57         //画边框
 58         //g.setColor(new Color());
 59         //g.drawRect(0,0,width-1,height-1);
 60         // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
 61         g.setColor(getRandColor(160,200));
 62         for (int i=0;i<155;i++) {
 63             int x = random.nextInt(width);
 64             int y = random.nextInt(height);
 65             int xl = random.nextInt(12);
 66             int yl = random.nextInt(12);
 67             g.drawLine(x,y,x+xl,y+yl);
 68         }
 69         // 取随机产生的认证码(4位数字)
 70         String sRand="";
 71         for (int i=0;i<4;i++){
 72             String rand=String.valueOf(random.nextInt(10));
 73
 74             if(Integer.parseInt(rand)%2==0){
 75                 rand=codeSequence[random.nextInt(36)]+"";
 76             }
 77
 78             sRand+=rand;
 79             // 将认证码显示到图象中
 80             g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
 81             g.drawString(rand,13*i+6,16);
 82         }
 83         // 将认证码存入SESSION
 84         session.setAttribute(params,sRand);
 85         // 图象生效
 86         g.dispose();
 87         ServletOutputStream responseOutputStream =response.getOutputStream();
 88         // 输出图象到页面
 89         ImageIO.write(image, "JPEG", responseOutputStream);
 90         //以下关闭输入流！
 91         responseOutputStream.flush();
 92         responseOutputStream.close();
 93     }
 94     Color getRandColor(int fc,int bc){//给定范围获得随机颜色
 95         Random random = new Random();
 96         if(fc>255) fc=255;
 97         if(bc>255) bc=255;
 98         int r=fc+random.nextInt(bc-fc);
 99         int g=fc+random.nextInt(bc-fc);
100         int b=fc+random.nextInt(bc-fc);
101         return new Color(r,g,b);
102     }
103 }

上面的代码注释想必已经描述的很清楚了，这里就不细说了。注意String params = request.getParameter("parame");session.setAttribute(params,sRand); 这是关键

 1        <servlet>
 2         <description>vCode</description>
 3         <display-name>vCode</display-name>
 4         <servlet-name>ValidateCodeServlet</servlet-name>
 5         <servlet-class>
 6             com.skss.util.ValidateCodeServlet
 7         </servlet-class>
 8     </servlet>
 9     <servlet-mapping>
10         <servlet-name>ValidateCodeServlet</servlet-name>
11         <url-pattern>/vcode</url-pattern>
12     </servlet-mapping>

web.xml代码，下面是vcode.jsp页面，后面的参数为了让这个验证码通用，同时保正每个页面的验证码不会因为其他引用的验证码刷新而改变

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 2 <%
 3     String path = request.getContextPath();
 4     String basePath = request.getScheme() + "://"
 5             + request.getServerName() + ":" + request.getServerPort()
 6             + path + "/";
 7     String type = request.getParameter("type");
 8 %>
 9 <script>
10 function refresh(){
11     document.location.href = document.location.href;
12 }
13 </script>
14 <img src="${path}/vcode?parame=<%= type%>" onclick="refresh()" style="cursor: pointer;" title="看不清！点击换一个！"/>

下面是引用这个jsp的iframe

1 <iframe frameborder="no" border="0" marginwidth="0" marginheight="0" scrolling="no" allowtransparency="yes" src="${path}/app/admin/login/vcode.jsp?type=login_vcode" style="width: 60px;height: 20px;padding: 0,0,0,0;" scrolling="no" ></iframe>

if (!user.getVcode().equalsIgnoreCase(
                    (String) this.request.getSession().getAttribute("login_vcode"))) {
                request.setAttribute("msg", "验证码错误！");
                return "loginx";
            }

简单 验证码 功能,布布扣,bubuko.com