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JavaEE会话技术之Session案例

tech2023-09-19  110

JavaEE会话技术之Session案例

案例需求：需求分析代码验证码代码登陆代码登陆页面代码登录成功页面

案例需求：

访问带有验证码的登录页面login.jsp用户输入用户户名和密码以及验证码。 * 如果用户名和密码输入有误，跳转登录页面， 提示用户名或者密码错误 *如果验证码输入有误，跳转登录页面， 提示：验证码错误 *如果输入全部正确，则转跳到主页success.jsp， 显示：用户名，欢迎您！

需求分析

代码

验证码代码

package com.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; @WebServlet("/checkCodeServlet") public class CheckCodeServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int width = 100; int height = 50; //1.创建一对象，在内存中图片(验证码图片对象) BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //2.美化图片 //2.1 填充背景色 Graphics g = image.getGraphics();//画笔对象 g.setColor(Color.PINK);//设置画笔颜色 g.fillRect(0,0,width,height); //2.2画边框 g.setColor(Color.BLUE); g.drawRect(0,0,width - 1,height - 1); 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 < 10; 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); } //3.将图片输出到页面展示 ImageIO.write(image,"jpg",response.getOutputStream()); } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }

登陆代码

package com.web.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("/loginServlet") public class LoginServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.设置request编码 request.setCharacterEncoding("utf-8"); //2.获取Map参数 String username = request.getParameter("username"); String password = request.getParameter("password"); String checkCode = request.getParameter("checkCode"); //先获取生成的验证码 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"); //3.判断验证码是否正确 if (checkCode_session!= null&&checkCode_session.equalsIgnoreCase(checkCode)){ //忽略大小写比较字符串 //验证码正确 //判断用户名和密码是否一致 if ("zhansan".equals(username)&&"123".equals(password)){ //登陆成功 //存储信息，用户信息 session.setAttribute("user",username); //重定向到success页面 response.sendRedirect(request.getContextPath()+"/success.jsp"); }else { //登陆失败 //储存提示信息到request request.setAttribute("login_error","用户名或密码错误"); //转发到登录页面 request.getRequestDispatcher("/login.jsp").forward(request,response); } }else{ //验证码不一致 //储存提示信息到request request.setAttribute("cc_error","验证码错误"); //转发到登录页面 request.getRequestDispatcher("/login.jsp").forward(request,response); } } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }

登陆页面代码

<%-- Created by IntelliJ IDEA. User: OldAZ-PC Date: 2020/9/3 Time: 16:30 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>login</title> <script> window.onload = function () { document.getElementById("img").onclick = function () { this.src = "/4_Cookie_Session_war_exploded/checkCodeServlet?date="+new Date().getTime(); } } </script> <style> div{ color: red; } </style> </head> <body> <form action="loginServlet" 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="/4_Cookie_Session_war_exploded/checkCodeServlet"></td> </tr> <tr> <td colspan="2"><input type="submit" value="登录"></td> </tr > </table> </form> <div><%=request.getAttribute("cc_error")==null?"":request.getAttribute("cc_error")%></div> <div><%=request.getAttribute("login_error")==null?"":request.getAttribute("login_error")%></div> </body> </html>

登录成功页面

<%-- Created by IntelliJ IDEA. User: OldAZ-PC Date: 2020/9/3 Time: 19:05 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1><%=request.getSession().getAttribute("user") %>,欢迎您！！</h1> </body> </html>
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