JavaWeb使用mvc模式實現(xiàn)登錄功能

更新時間：2022年01月28日 10:43:16 作者：書啟秋楓

本文主要介紹了JavaWeb使用mvc模式實現(xiàn)登錄功能，文中通過示例代碼介紹的非常詳細，具有一定的參考價值，感興趣的小伙伴們可以參考一下

部署項目、環(huán)境搭建

詳細內(nèi)容

1.導(dǎo)包

2.web >> index.jsp web >> login.jsp web >> success.jsp

1) web >> index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <a href="login.jsp">登錄</a>
  </body>
</html>

2) web >> login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>登錄</title>
  <style>
    #msg {
      color: red;
    }
  </style>
</head>
<body>
 
<form action="user" method="post">
  賬號：<input type="text" name="userName"><span id="msg"><%=request.getAttribute("msg")%></span>

  密碼：<input type="text" name="passWord">

  <input type="hidden" name="method" value="login">
  <input type="submit" value="登錄">
</form>
 
</body>
</html>

3) web >> success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="constant.Con" %>
<html>
<head>
    <title>用戶中心</title>
</head>
<body>
<%=request.getSession().getAttribute(Con.USER)%><h1 style="color: green">歡迎您</h1>
<a href="login.html">返回重新登錄</a>
</body>
</html>

3.constant >> Con

package constant;
 
import java.io.Serializable;
 
public class Con implements Serializable {
    //session中保存用戶登錄信息
    public static final String USER = "user";
}

entity >> User

package entity;
 
import java.io.Serializable;
 
public class User implements Serializable {
    private int id;
    private String userName;
    private String passWord;
 
    public User(int id, String userName, String passWord) {
        this.id = id;
        this.userName = userName;
        this.passWord = passWord;
    }
 
    public User() {
    }
 
    public int getId() {
        return id;
    }
 
    public void setId(int id) {
        this.id = id;
    }
 
    public String getUserName() {
        return userName;
    }
 
    public void setUserName(String userName) {
        this.userName = userName;
    }
 
    public String getPassWord() {
        return passWord;
    }
 
    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }
}

4.resources >> prop.properties

driverClassName=com.mysql.cj.jdbc.Driver
urlName=jdbc:mysql://localhost:3306/myjdbc?characterEncoding=utf8&useSSL=false&serverTimezone=UTC
userName=root
passwordName=root

5.utils >> JDBCUtils

package utils;
 
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
 
/*
    JDBC工具類
 */
public class JDBCUtils {
    // 聲明驅(qū)動的路徑
    static String driverClass;
    static String url;
    static String user;
    static String password;
 
    /*
        靜態(tài)代碼塊只會在加載class文件的時候執(zhí)行一次，
        將注冊驅(qū)動的代碼由靜態(tài)代碼塊來實現(xiàn)
     */
    static {
        // 創(chuàng)建屬性集對象
        Properties prop = new Properties();
        // 將文件中的數(shù)據(jù)讀取到屬性集中
        try {
            //prop.properties
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("prop.properties");
            prop.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 獲取key對應(yīng)的value
        driverClass = prop.getProperty("driverClassName");
        url = prop.getProperty("urlName");
        user = prop.getProperty("userName");
        password = prop.getProperty("passwordName");
        try {
            // 加載驅(qū)動
            Class.forName(driverClass);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
 
    /*
        將獲取資源的方法進行封裝: Connection連接接口對象
     */
    public static Connection getConnection() throws SQLException, ClassNotFoundException {
        // 獲取連接
        Connection connection = DriverManager.getConnection(url, user, password);
        return connection;
    }
 
    /*
        封裝方法，用于釋放資源
     */
    public static void close(Connection connection, Statement statement, ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        // 調(diào)用已經(jīng)實現(xiàn)功能的方法直接使用
        close(connection, statement);
    }
 
    /*
        重載一個釋放資源的代碼，用來釋放兩個資源
     */
    public static void close(Connection connection, Statement statement) {
        try {
            if (statement != null) {
                statement.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
 
}

6.servlet >> UserServlet

package servlet;
 
import constant.Con;
import service.UserService;
import service.impl.UserServiceImpl;
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.io.IOException;
 
@WebServlet(name = "user", urlPatterns = "/user")
public class UserServlet extends HttpServlet {
    private UserService userService = new UserServiceImpl();
 
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.設(shè)置請求字符集為utf-8
        req.setCharacterEncoding("utf-8");
        //2.獲取請求參數(shù)method,根據(jù)值調(diào)用不同方法處理業(yè)務(wù)
        String method = req.getParameter("method");
        if (method.equals("login")) {
            this.login(req, resp);
        }
    }
 
    //登錄方法
    private void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.獲取賬號和密碼
        String userName = req.getParameter("userName");
        String passWord = req.getParameter("passWord");
        //2.調(diào)用service的方法處理登錄
        boolean result = userService.checkUser(userName, passWord);
        if (result) {
            //true表示登錄成功
            //轉(zhuǎn)發(fā)跳轉(zhuǎn)成功頁面
            //req.getRequestDispatcher("/success.jsp").forward(req, resp);
            //將用戶信息保存在session域?qū)ο笾?
            req.getSession().setAttribute(Con.USER, userName);
            //重定向跳轉(zhuǎn)成功頁面
            resp.sendRedirect(req.getContextPath() + "/success.jsp");
        } else {
            //false登錄失敗，返回登錄頁面
            req.setAttribute("msg", "賬號密碼不匹配");
            req.getRequestDispatcher("/login.jsp").forward(req, resp);
        }
    }
}

7.service >> UserService service >> impl >> UserServiceImpl

package service;
 
public interface UserService {
    //判斷登錄成功與否
    boolean checkUser(String userName, String passWord);
}

package service.impl;
 
import dao.UserDao;
import dao.impl.UserDaoImpl;
import entity.User;
import service.UserService;
import utils.JDBCUtils;
import java.sql.Connection;
import java.util.List;
 
public class UserServiceImpl implements UserService {
    private UserDao userDao = new UserDaoImpl();
 
    @Override
    public boolean checkUser(String userName, String passWord) {
        // 連接對象
        Connection connection = null;
        try {
            //1.獲取數(shù)據(jù)庫連接
            connection = JDBCUtils.getConnection();
            //2.調(diào)用dao方法查詢數(shù)據(jù)
            List<User> users = userDao.findUserByUserNameAndPassWord(connection, userName, passWord);
            //3.根據(jù)查詢結(jié)果返回成功失敗標志
            if (users.size() > 0) {
                return true;
            } else {
                return false;
            }
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        } finally {
            JDBCUtils.close(connection, null);
        }
    }
}

8.dao >> UserDao dao >> impl >> UserDaoImpl

package dao;
 
import entity.User;
import java.sql.Connection;
import java.util.List;
 
public interface UserDao {
    //根據(jù)賬號密碼查詢數(shù)據(jù)庫，返回結(jié)果集
    List<User> findUserByUserNameAndPassWord(Connection connection, String userName, String passWord);
}

package dao.impl;
 
import dao.UserDao;
import entity.User;
import utils.JDBCUtils;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
 
public class UserDaoImpl implements UserDao {
    @Override
    public List<User> findUserByUserNameAndPassWord(Connection connection, String userName, String passWord) {
        // 發(fā)送sql語句對象
        PreparedStatement statement = null;
        List<User> userList = new ArrayList<>();
        try {
            connection = JDBCUtils.getConnection();
            // 獲取Statement對象
            statement = connection.prepareStatement("select * from user where username = ? and password = ?");
            statement.setString(1, userName);
            statement.setString(2, passWord);
 
            ResultSet rs = statement.executeQuery();
            while (rs.next()) {
                User user = new User();
                int id = rs.getInt(1);
                String username = rs.getString(2);
                String password = rs.getString(3);
                user.setId(id);
                user.setUserName(username);
                user.setPassWord(password);
 
                userList.add(user);
            }
            return userList;
        } catch (Exception e) {
            e.printStackTrace();
            return userList;
        } finally {
            JDBCUtils.close(null, statement, null);
        }
    }
}