Java后端学习路线笔记汇总表【黑马程序员】

Cookie和Session-学习笔记01【Cookie_快速入门、Cookie_细节】
Cookie和Session-学习笔记02【Cookie案例、JSP改造Cookie案例】
Cookie和Session-学习笔记03【Session快速入门、Session细节】
Cookie和Session-学习笔记04【Session之验证码案例】

第7节 Session之验证码案例

案例_验证码_需求&分析

案例_验证码_代码实现

将验证码存入session

案例_验证码_细节处理

细节处理1：美化页面

细节处理2：一次性验证码

代码总览

案例效果

代码1-login.jsp

代码2-LoginServlet.java

代码3-CookieTest.java

代码4-CheckCodeServlet.java

代码5-success.jsp

第7节 Session之验证码案例

案例_验证码_需求&分析

案例需求：

访问带有验证码的登录页面login.jsp
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：…

登录案例

案例_验证码_代码实现

将验证码存入session

案例_验证码_细节处理

细节处理1：美化页面

细节处理2：一次性验证码

代码总览

案例效果

用户名：zhangsan、密码：123

<%@ 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 = "/day16/checkCodeServlet?time=" + new Date().getTime();
            }
        }
    </script>
    <style>
        div {
            color: red;
        }
    </style>
</head>
<body>
    <form action="/day16/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="/day16/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>

代码2-LoginServlet.java

package cn.itcast.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 {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.设置request编码
        request.setCharacterEncoding("utf-8");
        //2.获取参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");
        //3.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.先判断验证码是否正确
        if (checkCode_session != null && checkCode_session.equalsIgnoreCase(checkCode)) {
            //忽略大小写进行比较
            //验证码正确
            //判断用户名和密码是否一致
            if ("zhangsan".equals(username) && "123".equals(password)) {//需要调用UserDao查询数据库
                //登录成功
                //存储信息，用户信息
                session.setAttribute("user", username);
                //重定向到success.jsp
                response.sendRedirect(request.getContextPath() + "/success.jsp");
            } else {
                //登录失败
                //存储提示信息到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
            //存储提示信息到request
            request.setAttribute("cc_error", "验证码错误");
            //转发到登录页面
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

代码3-CookieTest.java

package cn.itcast.cookie;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
 * 在服务器中的Servlet判断是否有一个名为lastTime的cookie
 * 1. 有：不是第一次访问
     * 1. 响应数据：欢迎回来，您上次访问时间为:2018年6月10日11:50:20
     * 2. 写回Cookie：lastTime=2018年6月10日11:50:01
 * 2. 没有：是第一次访问
     * 1. 响应数据：您好，欢迎您首次访问
     * 2. 写回Cookie：lastTime=2018年6月10日11:50:01
 */
@WebServlet("/cookieTest")
public class CookieTest extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置响应的消息体的数据格式以及编码
        response.setContentType("text/html;charset=utf-8");
        //1.获取所有Cookie
        Cookie[] cookies = request.getCookies();
        boolean flag = false;//没有cookie为lastTime
        //2.遍历cookie数组
        if (cookies != null && cookies.length > 0) {
            for (Cookie cookie : cookies) {
                //3.获取cookie的名称
                String name = cookie.getName();
                //4.判断名称是否是：lastTime
                if ("lastTime".equals(name)) {
                    //有该Cookie，不是第一次访问
                    flag = true;//有lastTime的cookie
                    //设置Cookie的value
                    //获取当前时间的字符串，重新设置Cookie的值，重新发送cookie
                    Date date = new Date();
                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
                    String str_date = sdf.format(date);
                    System.out.println("编码前：" + str_date);
                    //URL编码
                    str_date = URLEncoder.encode(str_date, "utf-8");
                    System.out.println("编码后：" + str_date);
                    cookie.setValue(str_date);
                    //设置cookie的存活时间
                    cookie.setMaxAge(60 * 60 * 24 * 30);//一个月
                    response.addCookie(cookie);
                    //响应数据
                    //获取Cookie的value，时间
                    String value = cookie.getValue();
                    System.out.println("解码前：" + value);
                    //URL解码：
                    value = URLDecoder.decode(value, "utf-8");
                    System.out.println("解码后：" + value);
                    response.getWriter().write("<h1>欢迎回来，您上次访问时间为:" + value + "！</h1>");
                    break;
                }
            }
        }
        if (cookies == null || cookies.length == 0 || flag == false) {
            //没有，第一次访问
            //设置Cookie的value
            //获取当前时间的字符串，重新设置Cookie的值，重新发送cookie
            Date date = new Date();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
            String str_date = sdf.format(date);
            System.out.println("编码前：" + str_date);
            //URL编码
            str_date = URLEncoder.encode(str_date, "utf-8");
            System.out.println("编码后：" + str_date);
            Cookie cookie = new Cookie("lastTime", str_date);
            //设置cookie的存活时间
            cookie.setMaxAge(60 * 60 * 24 * 30);//一个月
            response.addCookie(cookie);
            response.getWriter().write("<h1>您好，欢迎您首次访问！</h1>");
        }
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

代码4-CheckCodeServlet.java

package cn.itcast.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 {
    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());
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

代码5-success.jsp

<%@ 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>