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;
@Override
protected 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);
}
}