JavaWeb16.7【Cookie&Session：案例-登录验证码】
2021/7/3 14:21:44
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1 <%--
2 Created by IntelliJ IDEA.
3 User: yubaby
4 Date: 2021/7/3
5 Time: 12:32
6 To change this template use File | Settings | File Templates.
7 --%>
8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
9 <html>
10 <head>
11 <title>Title</title>
12
13 <script>
14 window.onload = function () {
15 document.getElementById("img").onclick = function () {
16 var timeStamp = new Date().getTime();
17 this.src = "/day16/checkCodeServlet?time=" + timeStamp;
18 //this即通过document.getElementById("img")获取到的对象
19 }
20 }
21 </script>
22 <style>
23 div{
24 color: red;
25 }
26 </style>
27 </head>
28 <body>
29
30 <form action="/day16/LoginServlet" method="post">
31 <table>
32 <tr>
33 <td>用户名</td>
34 <td><input type="text" name="username"></td>
35 </tr>
36 <tr>
37 <td>密码</td>
38 <td><input type="password" name="password"></td>
39 </tr>
40 <tr>
41 <td>验证码</td>
42 <td><input type="text" name="checkCode"></td>
43 </tr>
44 <tr>
45 <td colspan="2"><img id="img" src="/day16/checkCodeServlet"></td>
46 </tr>
47 <tr>
48 <td colspan="2"><input type="submit" value="登录"></td>
49 </tr>
50 </table>
51 </form>
52
53 <div><%=request.getAttribute("cc_error")==null ? "" : request.getAttribute("cc_error")%></div>
54 <div><%=request.getAttribute("login_error")==null ? "" : request.getAttribute("login_error")%></div>
55 </body>
56 </html>
1 <%--
2 Created by IntelliJ IDEA.
3 User: yubaby
4 Date: 2021/7/3
5 Time: 13:28
6 To change this template use File | Settings | File Templates.
7 --%>
8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
9 <html>
10 <head>
11 <title>Title</title>
12 </head>
13 <body>
14 <h1><%=request.getSession().getAttribute("user")%>,欢迎您</h1>
15 </body>
16 </html>
1 package com.haifei.servlet;
2
3 import javax.servlet.ServletException;
4 import javax.servlet.annotation.WebServlet;
5 import javax.servlet.http.HttpServlet;
6 import javax.servlet.http.HttpServletRequest;
7 import javax.servlet.http.HttpServletResponse;
8 import javax.servlet.http.HttpSession;
9 import java.io.IOException;
10 import java.util.Map;
11
12 /**
13 * session案例-登录验证码
14 */
15 @WebServlet("/LoginServlet")
16 public class LoginServlet extends HttpServlet {
17 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
18 //1 设置request编码
19 request.setCharacterEncoding("utf-8");
20 //2 获取参数集合
21 /*Map<String, String[]> parameterMap = request.getParameterMap();
22 for (String key: parameterMap.keySet()) {
23 String[] value = parameterMap.get(key);
24 System.out.println(key + ":" + value);
25 }*/
26 String username = request.getParameter("username");
27 String password = request.getParameter("password");
28 String checkCode = request.getParameter("checkCode");
29
30 //3 判断用户输入的验证码是否正确
31 //========================================
32 //获取checkCodeServlet生成的验证码
33 HttpSession session = request.getSession();
34 // Object checkCodeTruth = session.getAttribute("checkCodeTruth");
35 String checkCodeTruth = (String)session.getAttribute("checkCodeTruth"); //需要强转为字符串类型，不然equalsIgnoreCase报错
36 //用完之后立即删除session中存储的验证码，增强安全性(保证验证码的一次性使用)
37 session.removeAttribute("checkCodeTruth");
38 //========================================
39 if (checkCodeTruth!=null && checkCodeTruth.equalsIgnoreCase(checkCode)){ //忽略大小写比较字符串方法
40 //一致，用户输入验证码正确
41
42 //判断用户输入的用户名和密码是否正确
43 if ("zhangsan".equals(username) && "123".equals(password)){ //此处实际应该调用UserDao查询数据库数据
44 //登录成功
45
46 //存储用户信息
47 session.setAttribute("user", username); //此处实际应该传入查询出来的user对象
48 //重定向到success.jsp
49 response.sendRedirect(request.getContextPath() + "/success.jsp");
50 }else {
51 //登录失败
52
53 //存储提示信息到request
54 request.setAttribute("login_error", "用户名或密码错误");
55 //转发到登录页面
56 request.getRequestDispatcher("/login.jsp").forward(request, response);
57 }
58
59 }else {
60 //不一致，用户输入验证码不正确
61
62 //存储提示信息到request
63 request.setAttribute("cc_error", "验证码错误");
64 //转发到登录页面
65 request.getRequestDispatcher("/login.jsp").forward(request, response);
66 }
67
68 }
69
70 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
71 this.doPost(request, response);
72 }
73 }
1 package com.haifei.servlet;
2
3 import javax.imageio.ImageIO;
4 import javax.servlet.ServletException;
5 import javax.servlet.annotation.WebServlet;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9 import javax.servlet.http.HttpSession;
10 import java.awt.*;
11 import java.awt.image.BufferedImage;
12 import java.io.IOException;
13 import java.util.Random;
14
15 /**
16 * Response对象案例-验证码
17 */
18 @WebServlet("/checkCodeServlet")
19 public class CheckCodeServlet extends HttpServlet {
20 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
21 int width = 100;
22 int height = 50;
23
24 //1 创建对象，再内存中画图（验证码图片对象）
25 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
26
27 //2 美化图片
28 //2.1 填充背景色
29 Graphics g = image.getGraphics();//画笔对象
30 g.setColor(Color.PINK);//设置画笔颜色
31 g.fillRect(0,0,width,height);
32 //2.2画边框
33 g.setColor(Color.BLUE);
34 g.drawRect(0,0,width - 1,height - 1);
35 //2.3画验证码
36 String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
37 Random ran = new Random();
38 //========================================
39 StringBuilder sb = new StringBuilder();
40 //========================================
41 for (int i = 1; i <= 4; i++) {
42 //生成随机下标
43 int index = ran.nextInt(str.length());
44 //获取随机字符
45 char ch = str.charAt(index);
46 sb.append(ch);
47
48 //写验证码
49 g.drawString(ch+"",width/5*i,height/2);
50 }
51 //========================================
52 String checkCodeTruth = sb.toString();
53 //将生成的验证码存入session
54 HttpSession session = request.getSession();
55 session.setAttribute("checkCodeTruth", checkCodeTruth);
56 //========================================
57
58 //2.4画干扰线
59 g.setColor(Color.GREEN);
60 for (int i = 0; i < 10; i++) { //随机生成坐标点
61 int x1 = ran.nextInt(width);
62 int x2 = ran.nextInt(width);
63 int y1 = ran.nextInt(height);
64 int y2 = ran.nextInt(height);
65 g.drawLine(x1,y1,x2,y2);
66 }
67
68 //3 将图片输出到页面展示
69 ImageIO.write(image, "jpg", response.getOutputStream());
70 }
71
72 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
73 this.doPost(request, response);
74 }
75 }
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