带验证码的登录练习

package com.hopetesting.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;

/**
 * @author newcityman
 * @date 2019/9/1 - 20:42
 */
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        1、创建一个对象，在内存中存放图片（验证码图片对象）
        int width = 100;
        int height = 50;
        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();
        g.setColor(Color.PINK);
        g.fillRect(0, 0, width, height);

//        2.2、画矩形边框
        g.setColor(Color.blue);
        g.drawRect(0, 0, width - 1, height - 1);

//        2.3、随机生成角标
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random ran = new Random();

//        获取字符
        g.setColor(Color.RED);
        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= 4; i++) {
            int index = ran.nextInt(str.length());
            char c = str.charAt(index);
            sb.append(c);
            g.drawString(c + "", width / 5 * i, height / 2);
        }
        String checkcode_session = sb.toString();
        request.getSession().setAttribute("checkcode_session",checkcode_session);
//         2.4 设置干扰线
        g.setColor(Color.BLACK);

        for (int i = 0; i < 8; 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、将图片输送到页面显示
        ImageIO.write(image, "jpg", response.getOutputStream());


    }

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

package com.hopetesting.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;

/**
 * @author newcityman
 * @date 2019/9/4 - 23:22
 */
@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、  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");
//      4、判断验证码是否正确
        if (checkcode_session!=null && checkcode_session.equalsIgnoreCase(checkCode)) {
            //正确
            if ("zmy".equals(username) && "123".equals(password)) {
//                登陆成功
//                存储用户信息
                session.setAttribute("username", username);
//                重定向到success.jsp
                response.sendRedirect(request.getContextPath() + "/success.jsp");
            } else {
                //登陆失败
                request.setAttribute("login_error", "用户名或密码错误");
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            }
        } else {
            //错误
            request.setAttribute("cc_error", "验证码错误，请重试");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }

    }

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

<%@ 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>用戶名</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 src="/day16/checkCodeServlet" id="img" alt="验证码">
            </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>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
     <h1><%=request.getSession().getAttribute("username")%>,恭喜您成功登陆</h1>
</body>
</html>