用户登录时生成验证码页面

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1.生成验证页面

<%@ page language="java" import="java.util.*,java.awt.*" contentType="image/jpeg"%><%@ page import="java.awt.image.*"%><%@ page import="java.awt.Graphics,javax.imageio.*"%><%! Color getRandColor(int fc,int bc){      //在给定范围内获取随机颜色Random random = new Random();if(fc>255) fc=255;if(bc>255) bc=255;int r = fc+random.nextInt(bc-fc);int g = fc+random.nextInt(bc-fc);int b = fc+random.nextInt(bc-fc);return new Color(r,g,b);}%><%  response.setHeader("Pragma","No-cache");  response.setHeader("Cache-Control","no-cache");  response.setDateHeader("Expires",0);    //在内存中创建图像  int width=60,height=20;  BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);    //获取图形上下文  Graphics g = image.getGraphics();  //生成随机色  Random random = new Random();  //设定背景色  g.setColor(getRandColor(200,250));  g.fillRect(0,0,width,height);  //设定字体  g.setFont(new Font("Times New Roman",Font.PLAIN,18));  //画边框  g.setColor(getRandColor(160,200));  for(int i=0;i<155;i++){     int x= random.nextInt(width);     int y = random.nextInt(height);     int x1 = random.nextInt(12);     int y1 = random.nextInt(12);     g.drawLine(x,y,x1,y1);  }    //随机产生的认证码(4位数)  String sRand = "";  for(int i=0;i<4;i++){   String rand = String.valueOf(random.nextInt(10));   sRand +=rand;   g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));   g.drawString(rand,13*i+6,16);    } //将认证码存放在session中 session.setAttribute("rand",sRand); //图像生效 g.dispose(); //输出图像到页面 ImageIO.write(image,"JPEG",response.getOutputStream()); out.clear(); out = pageContext.pushBody();%>

2.用户登录页面，调用生成验证码页面

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>        <title>My JSP 'login.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><link rel="stylesheet" type="text/css" href="../css/login.css"><script type="text/javascript"> function checkForm(){                    if(checkUsername() && checkPass() && checkCode()){              return true;          }          return false;       }        function checkUsername(){        var name = document.getElementById("username").value;var namePattern=/^[a-zA-Z0-9]\w{0,15}$/;if(name.length == 0){   alert("用户名不能为空！");   return false;}if(!namePattern.test(name)){alert("用户名输入出错！");return false;}return true;}      function checkPass(){        var pass = document.getElementById("password").value;var pushMoneyPattern=/^[a-zA-Z0-9]\w{0,15}$/;   //表示只能是数字if(pass.length == 0){   alert("密码不能为空！");   return false;}if(!pushMoneyPattern.test(pass)){          alert("密码输入错误！");          return false;        } return true;   }      function checkCode(){      var code = document.getElementById("txtCheckCode").value;      var codePattern = /^[0-9]{4}$/;      if(code.length == 0){        alert("验证码不能为空!");        return false;      }      if(!codePattern.test(code)){        alert("验证码只能是四位数字！ ");        return false;      }      return true;   }   function loadimage(){       document.getElementById("randImage").src = "checkCode.jsp?"+Math.random();   }</script>     </head>    <body>   <form action="/Chapter06/BankLoginServlet" method="post" onsubmit="return checkForm()">   <table cellpadding="0" cellspacing="0" border="1px solid black" width="320px" height="120px">    <tr>     <td class="loginTitle">用户名：</td>     <td class="loginValue"><input type="text" name="username" /></td>    </tr>    <tr>     <td class="loginTitle">密  码：</td>     <td class="loginValue"><input type="password" name="password" size="21" /></td>    </tr>    <tr>     <td class="loginTitle">验证码：</td>     <td class="loginValue" nowrap>        <input type="text" name="txtCheckCode" id="txtCheckCode">        <img src="checkCode.jsp" name="randImage" id="randImage" alt="看不清换一张" onclick="javascript:loadimage();" />     </td>    </tr>    <tr>     <td id="btn" colspan="2">      <input type="submit" value="提交" />   <input type="reset" value="重置" />     </td>    </tr>             </table>   </form>  </body></html>

3.验证用户登录的servlet

package com.chapter06.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.chapter06.bo.UserBo;import com.chapter06.bo.impl.UserBoImpl;public class BankLoginServlet extends HttpServlet {/* * 对输入的用户名、密码和验证码进行验证 * */private UserBo userBo;@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {userBo = new UserBoImpl();response.setContentType("text/html;charset=gbk");PrintWriter out = response.getWriter();//获取表单中的数据String username = request.getParameter("username");String password = request.getParameter("password");String checkCode = request.getParameter("txtCheckCode");System.out.println(username);System.out.println(password);System.out.println(checkCode);//获取在session域中随机产生的验证码String randCode = request.getSession().getAttribute("rand").toString();System.out.println(randCode);         //首先对验证码进行判断        if(!checkCode.equals(randCode)){        out.print("<script>alert('验证码输入错误!');location.href='bankLogin/login.jsp';</script>");        }else{           if(userBo.validUserByNameAndPwd(username, password)){           request.setAttribute("username", username);           request.getRequestDispatcher("bankLogin/index.jsp").forward(request, response);           }else{           out.print("<script>alert('用户名或密码验证错误！');location.href='bankLogin/login.jsp';</script>");           }        }}protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {this.doGet(req, resp);}}