Java-用户登录验证案例

用户登录验证

1.案例需求：
    1.访问带有验证码的登录页面login.jsp
    2.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

代码如下

login.jsp

<%@ 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="/08__war_exploded/CheckCodeServlet?time="+new Date().getTime();
            }
        }
    </script>
    <style>
        div{
            color:red;
        }
    </style>
</head>
<body>
<form action="/08__war_exploded/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="/08__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>

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>

session

package cn.itcast.servlet;

import cn.itcast.entity.UserDao;
import cn.itcast.respository.UserRespository;

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 {
        //设置request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");
        //封装对象
        UserDao loginUser=new UserDao();
        loginUser.setUsername(username);
        loginUser.setPassword(password);

        // 实例化一个StudentResponsitory对象
        UserRespository userd = new UserRespository();

        String usernameone=userd.getList().getUsername();
        String passwordone=userd.getList().getPassword();
        // //判断userd
        // if(userd==null){
        //     //登录失败
        //     request.getRequestDispatcher("/failServlet").forward(request,response);
        // }else{
        //     //登录成功
        //     //存储数据
        //     request.setAttribute("userd",userd);
        //     //转发
        //     request.getRequestDispatcher("/successServlet").forward(request,response);
        // }
        // System.out.println("--------------1---------------");
        // System.out.println(usernameone);
        // System.out.println("---------------2--------------");
        // System.out.println(passwordone);
        // System.out.println("---------------3--------------");
        // System.out.println(userd.QueryAll());
        // System.out.println("---------------4--------------");
        // System.out.println(userd.getList().get(0).getUsername());
        // System.out.println("---------------5--------------");
        // System.out.println(userd.getList().get(0).getPassword());
        // System.out.println("---------------6--------------");

        //获取checkCode_session
        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");
        //先判断验证码是否正确
        if(checkCode_session!=null && checkCode_session.equalsIgnoreCase(checkCode)){
            //忽略大小写比较
            //验证码正确
            //判断用户名和密码是否一致
            if(usernameone.equals(username)&&passwordone.equals(password)){
                //需要调用数据库来进行操作
                //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","用户名或者密码错误");
                //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);
    }
}

验证码设计

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;
        //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);
        //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 = "ABCDEFGHIJKLMNOPQRSTOVWXYZabcdefghijklmnopqrstovwxyz";
        //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);
            g.drawString(ch + "", width / 5 * i, height / 2);
            //2.3.写验证码
        }
        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);
        for (int i = 0; i <= 4; i++) {
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);
            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1, x1, x2, y2);
        }

        //将图片输出到页面显示
        ImageIO.write(image, "jpg", response.getOutputStream());
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}
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Java-用户登录验证案例
用户登录验证
代码如下
login.jsp
success.jsp
session
验证码设计
发布于 2020-06-04 15:40
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