Servlet和JSP验证码登录简单实现

2021-04-14

程序实现主要分四部分组成

1.login.jsp
<%--
  Created by IntelliJ IDEA.
  User: IDEA
  Date: 4/13/2021
  Time: 4:26 PM
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Login Page</title>
    <script>
        window.onload = function (){
            document.getElementById("img").onclick =function (){
                this.src = "/day08/checkCodeServlet?time="+new Date().getTime();
            }
        }
    </script>

    <style>
        div{
            color: red;
        }
    </style>
</head>
<body>
<form action="/day08/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 src="/day08/checkCodeServlet"  id="img"></td>
        </tr>
        <tr>
            <td colspan="2"><input type="submit" value="login"></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>
2.LoginServlet.java
package com.levizhao.servlet;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       // 设置请求默认编码
        request.setCharacterEncoding("utf-8");

        // 获取参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");

        //获取session中的验证码
        HttpSession session = request.getSession();
        String checkCode_session = (String)session.getAttribute("checkCode_session");
        // 获取到session的值之后 使用一次就失效
        session.removeAttribute("checkCode_session");
        // 判断验证码验证是否正确
        if (checkCode_session != null && checkCode_session.equalsIgnoreCase(checkCode)){
            // 验证码正确
            if ("levi".equals(username) && "123".equals(password)){
                // 账户和密码正确
               session.setAttribute("user",username);
                response.sendRedirect(request.getContextPath()+"/success.jsp");
            }else {
                // 账户或者密码错误
                request.setAttribute("login_error","The Username or Password is incorrect");
                request.getRequestDispatcher("/login.jsp").forward(request,response);
            }

        }
        else{
            // 验证码不正确
            request.setAttribute("cc_error","The Check Code is incorrect");
            request.getRequestDispatcher("/login.jsp").forward(request,response);

        }


    }
}
3.CheckCodeServlet.java
package com.levizhao.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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.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 = 200;
        int height = 100;

        //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.DARK_GRAY);//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();
        g.setColor(Color.yellow);
        // 设置验证字符的大小
        g.setFont(new Font("Arial",Font.BOLD,22));
        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

            // 把字符存在StringBuilder中
            sb.append(ch);
            //2.3写验证码
            g.drawString(ch+"",width/5*i,height/2);

        }
        // 把存在sb中的字符转化为字符串然后存到session中
        String checkCode_session = sb.toString();
        HttpSession session = request.getSession();
        session.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);
    }
}
4.success.jsp
<%--
  Created by IntelliJ IDEA.
  User: IDEA
  Date: 4/14/2021
  Time: 10:49 AM
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>login Successful</title>
</head>
<body>
<h1>Welcome to <%=request.getSession().getAttribute("user")%> login successful.</h1>
</body>
</html>
posted @ 2021-04-14 17:08  withLevi  阅读(237)  评论(0)  编辑  收藏  举报