今天实现了需求征集系统的登录页面
html<%--
Created by IntelliJ IDEA.
User: 张志伟
Date: 2020/10/20
Time: 18:37
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登录</title>
<link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">
<script src="bootstrap/js/jquery-3.5.1.min.js"></script>
<script src="bootstrap/js/bootstrap.min.js"></script>
<script type="text/javascript">
<%--切换验证码--%>
function refreshCode(){
//获取验证码对象
let vcode = document.getElementById("vcode");
//设置其src属性，加时间戳
vcode.src="${pageContext.request.contextPath}/checkCodeServlet?time="+new Date().getTime();
}
</script>
</head>
<body>
<!--导航栏-->
<nav class="navbar navbar-inverse">
<div class="container-fluid">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">重大需求征集系统 <small>V1.0</small></a>
</div>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</nav>
<!--导航栏-->
<div class="container-fluid">
<!--标题用户登录-->
<div class="row">
<div class="col-sm-6 col-sm-offset-3">
<h2 class="text-center ">用户登录</h2>
</div>
</div>
<!--登录表单-->
<div class="row">
<div class="col-sm-4 col-sm-offset-4">
<form>
<div class="form-group">
<label for="username">用户名</label>
<input type="text" class="form-control" id="username" placeholder="用户名">
</div>
<div class="form-group">
<label for="password">密码</label>
<input type="password" class="form-control" id="password" placeholder="密码">
</div>
<div class="form-group">
<label for="code">验证码</label>
<div class="row">
<div class="col-sm-8">
<input type="text" class="form-control" id="code" placeholder="验证码">
</div>
<div class="col-sm-4">
<a href="javascript:refreshCode();">
<img src="${pageContext.request.contextPath}/checkCodeServlet" id="vcode" class="img-responsive" alt="" title="看不清？换一张" >
</a>
</div>
</div>
</div>
<button type="submit" class="btn btn-danger btn-block">登录</button>
<a href="register.jsp" class="btn btn-info btn-block">注册</a>
</form>
</div>
</div>
</div>
</body>
</html>
下面是验证码部分
package web.servlet;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
/**
* 验证码
*/
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
//服务器通知浏览器不要缓存
response.setHeader("pragma","no-cache");
response.setHeader("cache-control","no-cache");
response.setHeader("expires","0");
//在内存中创建一个长80，宽30的图片，默认黑色背景
//参数一：长
//参数二：宽
//参数三：颜色
int width = 80;
int height = 30;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取画笔
Graphics g = image.getGraphics();
//设置画笔颜色为灰色
g.setColor(Color.WHITE);
//填充图片
g.fillRect(0,0, width,height);
//产生4个随机验证码，12Ey
String checkCode = getCheckCode();
//将验证码放入HttpSession中
request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);
//设置画笔颜色为黄色
g.setColor(Color.CYAN);
//设置字体的小大
g.setFont(new Font("黑体", Font.BOLD,24));
//向图片上写入验证码
g.drawString(checkCode,15,25);
//将内存中的图片输出到浏览器
//参数一：图片对象
//参数二：图片的格式，如PNG,JPG,GIF
//参数三：图片输出到哪里去
ImageIO.write(image,"PNG",response.getOutputStream());
}
/**
* 产生4位随机字符串
*/
private String getCheckCode() {
String base = "0123456789ABCDEFGabcdefg";
int size = base.length();
Random r = new Random();
StringBuffer sb = new StringBuffer();
for(int i=1;i<=4;i++){
//产生0到size-1的随机值
int index = r.nextInt(size);
//在base字符串中获取下标为index的字符
char c = base.charAt(index);
//将c放入到StringBuffer中去
sb.append(c);
}
return sb.toString();
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request,response);
}
}