Java-用戶登陸驗證案例

時間 2020-06-05

標籤 java 用戶登陸驗證案例欄目 Java 简体版

原文原文鏈接

用戶登陸驗證

1.案例需求：
    1.訪問帶有驗證碼的登陸頁面login.jsp
    2.用戶輸入用戶名，密碼以及驗證碼
        * 若是用戶名和密碼輸入有誤，跳轉登陸頁面，提示：用戶名或密碼錯誤
        * 若是驗證碼輸入有誤，跳轉登陸頁面，提示：驗證碼錯誤
        * 若是所有輸入正確，則跳轉到主頁success.jsp，顯示：用戶名，歡迎您

代碼以下

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>用戶名</td>
            <td><input type="text" name="username"></td>
        </tr>
        <tr>
            <td>密碼</td>
            <td><input type="password" name="password"></td>
        </tr>
        <tr>
            <td>驗證碼</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="登陸"></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")%>,歡迎您</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 {
        //設置request編碼
        request.setCharacterEncoding("utf-8");
        //獲取參數
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String checkCode=request.getParameter("checkCode");
        //封裝對象
        UserDao loginUser=new UserDao();
        loginUser.setUsername(username);
        loginUser.setPassword(password);

        // 實例化一個StudentResponsitory對象
        UserRespository userd = new UserRespository();

        String usernameone=userd.getList().getUsername();
        String passwordone=userd.getList().getPassword();
        // //判斷userd
        // if(userd==null){
        //     //登陸失敗
        //     request.getRequestDispatcher("/failServlet").forward(request,response);
        // }else{
        //     //登陸成功
        //     //存儲數據
        //     request.setAttribute("userd",userd);
        //     //轉發
        //     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--------------");

        //獲取checkCode_session
        HttpSession session=request.getSession();
        String checkCode_session=(String) session.getAttribute("checkCode_session");
        //刪除session中存儲的驗證碼
        session.removeAttribute("checkCode_session");
        //先判斷驗證碼是否正確
        if(checkCode_session!=null && checkCode_session.equalsIgnoreCase(checkCode)){
            //忽略大小寫比較
            //驗證碼正確
            //判斷用戶名和密碼是否一致
            if(usernameone.equals(username)&&passwordone.equals(password)){
                //須要調用數據庫來進行操做
                //登陸成功
                //存儲信息，用戶信息
                session.setAttribute("user",username);
                //重定向到success.jsp
                response.sendRedirect(request.getContextPath()+"/success.jsp");
            }else{
                //登陸失敗
                //存儲提示信息到request
                request.setAttribute("login_error","用戶名或者密碼錯誤");
                //轉發到登陸頁面
                request.getRequestDispatcher("/login.jsp").forward(request,response);
            }
        }else{
            //驗證碼不一致
            //存儲提示信息到request

            request.setAttribute("cc_error","驗證碼錯誤");
            //轉發到登陸頁面
            request.getRequestDispatcher("/login.jsp").forward(request,response);
        }
    }

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

驗證碼設計

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;
        //建立一對象，在內存中圖片（驗證碼圖片對象）
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //美化圖片
        //2.1.填充背景色
        Graphics g = image.getGraphics();//畫筆對象
        g.setColor(Color.pink);//設置畫筆顏色
        g.fillRect(0, 0, width, height);
        //2.2.畫邊框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width - 1, height - 1);

        String str = "ABCDEFGHIJKLMNOPQRSTOVWXYZabcdefghijklmnopqrstovwxyz";
        //生成隨機角標
        Random ran = new Random();
        StringBuilder sb=new StringBuilder();
        for (int i = 1; i <= 4; i++) {
            int index = ran.nextInt(str.length());
            //獲取字符
            char ch = str.charAt(index);//隨機字符
            sb.append(ch);
            g.drawString(ch + "", width / 5 * i, height / 2);
            //2.3.寫驗證碼
        }
        String checkCode_session=sb.toString();
        //將驗證碼存入session
        request.getSession().setAttribute("checkCode_session",checkCode_session);

        //2.4畫干擾線
        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);
        }

        //將圖片輸出到頁面顯示
        ImageIO.write(image, "jpg", response.getOutputStream());
    }

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