Java 之 Session 包含验证码登录案例

需求：

　　1. 访问带有验证码的登录页面login.jsp
　　2. 用户输入用户名，密码以及验证码。
　　　　如果用户名和密码输入有误，跳转登录页面，提示:用户名或密码错误
　　　　如果验证码输入有误，跳转登录页面，提示：验证码错误
　　　　如果全部输入正确，则跳转到主页success.jsp，显示：用户名,欢迎您

分析：

代码实现：

　　login.jsp 页面

 <%@ page contentType="text/html;charset=UTF-8" language="java" %>

 <html lang="en">

 <head>

     <meta charset="UTF-8">

     <title>登录</title>

     <script>

         window.onloa = function() {

             // 刷新验证码

             document.getElementById("img").onclick = function() {

                 this.src = "/day13/checkcodeservletdemo"+new Date().getTime();

             }

         }

     </script>

     <style>

         div {

             color:red;

         }

     </style>

 <body>

     <form action="/day13/loginservletdemo" method="post">

         <table>

             <tr>

                 <td>用户名</td>

                 <td><input type="text" name="username"></td>

             </tr>

             <tr>

                 <td>密码</td>

                 <td><input type="password" name="password"></td>

             </tr>

             <tr>

                 <td>验证码</td>

                 <td><input type="text" name="checkcode"></td>

             </tr>

             <tr>

                <td colspan="2"><img id="img" src="/day13/checkcodeservletdemo"></td>

             </tr>

             <tr>

                 <td colspan="2"><input type="submit" value="登录"></td>

             </tr>

         </table>

         <div><%=request.getAttribute("cc_error") == null ? "":request.getAttribute("cc_error") %></div>

         <div><%=request.getAttribute("login_error") == null ? "":request.getAttribute("login_error") %></div>

     </form>

 </body>

 </html>

　　success 页面

 <%@ page contentType="text/html;charset=UTF-8" language="java" %>

 <html>

 <head>

     <title>登录成功</title>

 </head>

 <body>

     <h1><%=request.getSession().getAttribute("user")%>,欢迎您</h1>

 </body>

 </html>

　　生成验证码 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;

 @WebServlet("/checkcodeservletdemo")

 public class CheckCodeServlet extends HttpServlet {

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         // 定义图片的宽高

         int width = 100;

         int height = 50;

         // 1 创建对象，在内存中生成图片（验证码图片对象）

         BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);

         // 2 修饰图片

         // 2.1 填充背景色

         Graphics g = image.getGraphics(); //获取画笔对象

         g.setColor(Color.pink);  // 设置画笔颜色

         g.fillRect(0,0,width,height);  // 绘制一个矩形，给定坐标与宽高

         // 2.2 画边框

         g.setColor(Color.blue);    // 设置画笔颜色

         g.drawRect(0,0,width-1,height-1);  // 给图像绘制边框

         String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";

         //生成随机角标

         Random ran = new Random();

         StringBuilder sb = new StringBuilder();

         for (int i = 1; i <= 4; i++) {

             int index = ran.nextInt(str.length());

             //获取字符

             char ch = str.charAt(index);//随机字符

             sb.append(ch);

             //2.3写验证码

             g.drawString(ch+"",width/5*i,height/2);

         }

         String checkCode_session = sb.toString();

         // 将验证码存入 session

         request.getSession().setAttribute("checkCode_session",checkCode_session);

         //2.4画干扰线

         g.setColor(Color.GREEN);

         // 随机生成坐标点

         for (int i = 0; i < 6; i++) {

             int x1 = ran.nextInt(width);

             int x2 = ran.nextInt(width);

             int y1 = ran.nextInt(height);

             int y2 = ran.nextInt(height);

             g.drawLine(x1,y1,x2,y2);  // 画干扰线

         }

         // 3 将图片输出到页面展示：通过response 的 字符流，将图片输出到浏览器上

         ImageIO.write(image,"jpg",response.getOutputStream());

     }

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         this.doPost(request, response);

     }

 }

　　登录 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;

 @WebServlet("/loginservletdemo")

 public class LoginServlet extends HttpServlet {

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         // 1. 设置编码

         request.setCharacterEncoding("utf-8");

         // 2. 获取参数

         //Map<String, String[]> map = request.getParameterMap();

         String username = request.getParameter("username");

         String password = request.getParameter("password");

         String checkcode = request.getParameter("checkcode");

         // 3.先判断验证码是否正确

         // 获取生成验证码

         HttpSession session = request.getSession();

         String checkCode_session = (String) session.getAttribute("checkCode_session");

         // 删除 session中存储的验证码

         session.removeAttribute("checkCode_session");

         // 判断,忽略大小写

         if(checkCode_session!= null && checkCode_session.equalsIgnoreCase(checkcode)) {

             //验证码正确

             // 判断用户名和密码是否一致

             if("zhangsan".equals(username) && "123".equals(password)) {

                 // 登录成功

                 // 存储用户信息

                 session.setAttribute("user",username);

                 // 重定向到 success.jsp

                 response.sendRedirect(request.getContextPath()+"/success.jsp");

             }else {

                 // 存储提示信息到request

                 request.setAttribute("login_error","用户名或密码错误");

                 request.getRequestDispatcher("/login.jsp").forward(request,response);

             }

         } else {

             // 验证码不正确

             // 存储提示信息到request

             request.setAttribute("cc_error","验证码错误");

             request.getRequestDispatcher("/login.jsp").forward(request,response);

         }

     }

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         this.doPost(request, response);

     }

 }

巴特西

Java 之 Session 包含验证码登录案例

需求：

分析：

代码实现：

最新文章

热门文章