需求
用户登录的时候使用验证码进行验证
步骤
一、
LoginServlet实现步骤:
web网页页面部分
登陆页面主要使用bootstrap框架写的
Java类部分
验证码类 PicCodeServlet 的代码部分
package com.zjs.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 javax.servlet.http.HttpSession; import java.awt.*; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; @WebServlet(name = "PicCodeServlet", urlPatterns = "/code") public class PicCodeServlet extends HttpServlet { //创建一个随机类 private Random ran = new Random(); //写一个方法随机生成一种颜色 private Color getRandomColor() { //随机生成0~255之间的数 int red = ran.nextInt(256); int green = ran.nextInt(256); int blue = ran.nextInt(256); //红,绿,蓝 return new Color(red, green, blue); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1. 创建缓存图片 int width = 90, height = 30; //参数:宽,高,图片模式 BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //2. 获取画笔对象 Graphics graphics = img.getGraphics(); //3. 设置画笔颜色 graphics.setColor(Color.WHITE); //4. 填充矩形区域 graphics.fillRect(0, 0, width, height); //5. 从字符数组中随机得到字符 char[] arr = { 'A', 'B', 'C', 'D', 'N', 'E', 'W', 'b', 'o', 'y', '1', '2', '3', '4','5','6' }; //6. 循环4次,画4个字符 //new一个空字符用来存储验证码字符串 StringBuilder sb = new StringBuilder(); for (int i = 0; i < 4; i++) { //7. 设置字的颜色为随机 graphics.setColor(getRandomColor()); //8. 设置字体,大小为19 graphics.setFont(new Font(Font.SANS_SERIF,Font.BOLD+Font.ITALIC,19)); //随机得到下标 int index = ran.nextInt(arr.length); char c = arr[index]; //将循环得到的字符拼接成字符串 sb.append(c); //随机得到一个字符 //9. 将每个字符画到图片,x增加,y不变。 graphics.drawString(String.valueOf(c),10+(i*20), 20); } //将验证码以字符串的方式放到会话域中 HttpSession session = request.getSession(); System.out.println("验证码:"+sb.toString()); session.setAttribute("code",sb.toString()); //11. 画8条干扰线,每条线的颜色不同 for (int i = 0; i < 8; i++) { //10. 线的位置是随机的,x范围在width之中,y的范围在height之中。 int x1 = ran.nextInt(width); int y1 = ran.nextInt(height); int x2 = ran.nextInt(width); int y2 = ran.nextInt(height); graphics.setColor(getRandomColor()); graphics.drawLine(x1,y1,x2,y2); } //12. 将缓存的图片输出到响应输出流中 //参数:图片对象,图片格式,输出流 ImageIO.write(img,"jpg",response.getOutputStream()); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
login.html代码部分
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>会员登录</title> <link rel="stylesheet" href="css/bootstrap.min.css" type="text/css" /> <script src="js/jquery-1.11.3.min.js" type="text/javascript"></script> <script src="js/bootstrap.min.js" type="text/javascript"></script> <!-- 引入自定义css文件 style.css --> <link rel="stylesheet" href="css/style.css" type="text/css"/> <style> body{ margin-top:20px; margin:0 auto; } .carousel-inner .item img{ width:100%; height:300px; } .container .row div{ /* position:relative; float:left; */ } font { color: #666; font-size: 22px; font-weight: normal; padding-right:17px; } </style> </head> <body> <!-- 描述:菜单栏 --> <div class="container-fluid"> <div class="col-md-4"> <img src="img/logo2.png" /> </div> <div class="col-md-5"> <img src="img/header.png" /> </div> <div class="col-md-3" style="padding-top:20px"> <ol class="list-inline"> <li><a href="login.htm">登录</a></li> <li><a href="register.htm">注册</a></li> <li><a href="cart.htm">购物车</a></li> </ol> </div> </div> <!-- 描述:导航条 --> <div class="container-fluid"> <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="#">首页</a> </div> <!-- Collect the nav links, forms, and other content for toggling --> <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1"> <ul class="nav navbar-nav"> <li class="active"><a href="#">手机数码<span class="sr-only">(current)</span></a></li> <li><a href="#">电脑办公</a></li> <li><a href="#">电脑办公</a></li> <li><a href="#">电脑办公</a></li> </ul> <form class="navbar-form navbar-right" role="search"> <div class="form-group"> <input type="text" class="form-control" placeholder="Search"> </div> <button type="submit" class="btn btn-default">Submit</button> </form> </div> <!-- /.navbar-collapse --> </div> <!-- /.container-fluid --> </nav> </div> <div class="container" style="width:100%;height:460px;background:#FF2C4C url('img/loginbg.jpg') no-repeat;"> <div class="row"> <div class="col-md-7"> <!--<img src="./img/login.jpg" width="500" height="330" alt="会员登录" title="会员登录">--> </div> <div class="col-md-5"> <div style="width:440px;border:1px solid #E7E7E7;padding:20px 0 20px 30px;border-radius:5px;margin-top:60px;background:#fff;"> <font>会员登录</font>USER LOGIN <div> </div> <form class="form-horizontal" action="login"> <div class="form-group"> <label for="username" class="col-sm-2 control-label">用户名</label> <div class="col-sm-6"> <input type="text" class="form-control"name="username" id="username" placeholder="请输入用户名"> </div> </div> <div class="form-group"> <label for="password" class="col-sm-2 control-label">密码</label> <div class="col-sm-6"> <input type="password" class="form-control"name="password" id="password" placeholder="请输入密码"> </div> </div> <div class="form-group"> <label for="code" class="col-sm-2 control-label">验证码</label> <div class="col-sm-3"> <input type="text" name="code" class="form-control" id="code" placeholder="请输入验证码"> </div> <div class="col-sm-3"> <img src="code" title="看不清,请重试" style="cursor: pointer" id="imgcode"/> <script type="text/javascript"> document.getElementById("imgcode").onclick=function (ev) { this.src="code?t="+Math.random(); } </script> </div> </div> <div class="form-group"> <div class="col-sm-offset-2 col-sm-10"> <div class="checkbox"> <label> <input type="checkbox"> 自动登录 </label> <label> <input type="checkbox"> 记住用户名 </label> </div> </div> </div> <div class="form-group"> <div class="col-sm-offset-2 col-sm-10"> <input type="submit" width="100" value="登录" name="submit" border="0" style="background: url('./img/login.gif') no-repeat scroll 0 0 rgba(0, 0, 0, 0); height:35px;width:100px;color:white;"> </div> </div> </form> </div> </div> </div> </div> <div style="margin-top:50px;"> <img src="./img/footer.jpg" width="100%" height="78" alt="我们的优势" title="我们的优势" /> </div> <div style="text-align: center;margin-top: 5px;"> <ul class="list-inline"> <li><a>关于我们</a></li> <li><a>联系我们</a></li> <li><a>招贤纳士</a></li> <li><a>法律声明</a></li> <li><a>友情链接</a></li> <li><a target="_blank">支付方式</a></li> <li><a target="_blank">配送方式</a></li> <li><a>服务声明</a></li> <li><a>广告声明</a></li> </ul> </div> <div style="text-align: center;margin-top: 5px;margin-bottom:20px;"> Copyright © 2005-2016 </div> </body></html>
**主要是验证码部分的代码,我截出来了,如下图**
LoginServlet实现步骤:
代码部分
package com.zjs.servlet; 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 javax.servlet.http.HttpSession; import java.io.IOException; import java.io.PrintWriter; @WebServlet(name = "LoginServlet", urlPatterns = "/login") public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置字符集 response.setContentType("text/html;charset=utf-8"); //得到打印流 PrintWriter out = response.getWriter(); //得到会话域 HttpSession session = request.getSession(); //得到登陆页面上显示得验证码 String code = (String) session.getAttribute("code"); //得到用户输入得验证码 String code1 = request.getParameter("code"); //用户输入的验证码与登陆页面上显示得验证码进行比较 if (code.equalsIgnoreCase(code1)){ //用户名与密码主要是从数据库中查询得,这个案例主要是验证 验证码,这里就不演示访问数据库了 //得到用户名 String username=request.getParameter("username"); //得到用户密码 String password=request.getParameter("password"); //如果用户名和密码分别等于ljm,520的话验证就通过 if ("ljm".equals(username)&&"520".equals(password)){ //将用户信息存到会话域中 session.setAttribute("username",username); //转发到welcome request.getRequestDispatcher("welcome").forward(request, response); } else { //写js脚本用来提示 out.print("<script>"); out.print("alert('用户名或密码不正确');"); out.print("location.href='login.html';"); out.print("</script>"); } } else { out.print("<script>"); out.print("alert('验证码不正确');"); out.print("location.href='login.html';"); out.print("</script>"); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
WelcomeServlet的实现步骤:
7. 会话域中取出用户信息并且显示
8. 判断用户是否正常登录,如果是非法用户则跳转到登录页面
9. 在页面上输出一个注销的连接,点注销跳转到LogoutServlet
代码部分
package com.zjs.servlet; 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 javax.servlet.http.HttpSession; import java.io.IOException; import java.io.PrintWriter; @WebServlet(name = "WelcomeServlet", urlPatterns = "/welcome") public class WelcomeServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置字符集 response.setContentType("text/html;charset=utf-8"); //得到打印流 PrintWriter out = response.getWriter(); //得到会话域 HttpSession session = request.getSession(); ////从会话域中得到用户名 String username = (String) session.getAttribute("username"); //登陆成功后判断用户名是否为空,如果为空,重定向到登陆页面 if (username==null){ response.sendRedirect("login.html"); return; } out.print("欢迎来到我的世界"+session.getAttribute("username")+"<br/>"); //如果点退出,就跳转到logout页面 out.print("<a href='logout'>退出</a>"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
三、 LogoutServlet的实现步骤:
10. 让会话立刻过期
11. 显示您已经成功退出
代码部分
package com.zjs.servlet; 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.io.IOException; @WebServlet(name = "logoutServlet", urlPatterns = "/logout") public class logoutServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //得到会话域后 让会话域立刻失效 request.getSession().invalidate(); //并且重定向到登陆页面 response.sendRedirect("login.html"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
效果截图
一、
登陆页面:
二、
1.输入正确的用户名和密码
2.输入正确的用户名和密码后跳转到的页面
三、点退出后会跳回上面显示的登陆页面
四、输入错误的验证码以及弹出的提示
五、输入错误的用户名或密码以及提示