JavaWeb如何使用mvc模式实现登录功能

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部署项目、环境搭建

详细内容

1.导包

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

1) web >> index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>            登录  

2) web >> login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>       
  账号：<%=request.getAttribute("msg")%>  密码：    
 

3) web >> success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ page import="constant.Con" %>    <%=request.getSession().getAttribute(Con.USER)%>
欢迎您
返回重新登录

3.constant >> Con

package constant; import java.io.Serializable; public class Con implements Serializable {    //session中保存用户登录信息    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.DriverurlName=jdbc:mysql://localhost:3306/myjdbc?characterEncoding=utf8&useSSL=false&serverTimezone=UTCuserName=rootpasswordName=root

5.utils >> JDBCUtils

package utils; import java.io.IOException;import java.io.InputStream;import java.sql.*;import java.util.Properties; /*    JDBC工具类 */public class JDBCUtils {    // 声明驱动的路径    static String driverClass;    static String url;    static String user;    static String password;     /*        静态代码块只会在加载class文件的时候执行一次，        将注册驱动的代码由静态代码块来实现     */    static {        // 创建属性集对象        Properties prop = new Properties();        // 将文件中的数据读取到属性集中        try {            //prop.properties            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("prop.properties");            prop.load(is);        } catch (IOException e) {            e.printStackTrace();        }        // 获取key对应的value        driverClass = prop.getProperty("driverClassName");        url = prop.getProperty("urlName");        user = prop.getProperty("userName");        password = prop.getProperty("passwordName");        try {            // 加载驱动            Class.forName(driverClass);        } catch (ClassNotFoundException e) {            e.printStackTrace();        }    }     /*        将获取资源的方法进行封装: Connection连接接口对象     */    public static Connection getConnection() throws SQLException, ClassNotFoundException {        // 获取连接        Connection connection = DriverManager.getConnection(url, user, password);        return connection;    }     /*        封装方法，用于释放资源     */    public static void close(Connection connection, Statement statement, ResultSet resultSet) {        try {            if (resultSet != null) {                resultSet.close();            }        } catch (SQLException e) {            e.printStackTrace();        }        // 调用已经实现功能的方法直接使用        close(connection, statement);    }     /*        重载一个释放资源的代码，用来释放两个资源     */    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.设置请求字符集为utf-8        req.setCharacterEncoding("utf-8");        //2.获取请求参数method,根据值调用不同方法处理业务        String method = req.getParameter("method");        if (method.equals("login")) {            this.login(req, resp);        }    }     //登录方法    private void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //1.获取账号和密码        String userName = req.getParameter("userName");        String passWord = req.getParameter("passWord");        //2.调用service的方法处理登录        boolean result = userService.checkUser(userName, passWord);        if (result) {            //true表示登录成功            //转发跳转成功页面            //req.getRequestDispatcher("/success.jsp").forward(req, resp);            //将用户信息保存在session域对象中            req.getSession().setAttribute(Con.USER, userName);            //重定向跳转成功页面            resp.sendRedirect(req.getContextPath() + "/success.jsp");        } else {            //false登录失败，返回登录页面            req.setAttribute("msg", "账号密码不匹配");            req.getRequestDispatcher("/login.jsp").forward(req, resp);        }    }}

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

package service; public interface UserService {    //判断登录成功与否    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) {        // 连接对象        Connection connection = null;        try {            //1.获取数据库连接            connection = JDBCUtils.getConnection();            //2.调用dao方法查询数据            List users = userDao.findUserByUserNameAndPassWord(connection, userName, passWord);            //3.根据查询结果返回成功失败标志            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 {    //根据账号密码查询数据库，返回结果集    List 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 findUserByUserNameAndPassWord(Connection connection, String userName, String passWord) {        // 发送sql语句对象        PreparedStatement statement = null;        List userList = new ArrayList<>();        try {            connection = JDBCUtils.getConnection();            // 获取Statement对象            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);        }    }}

登录实现

1.首页 index.jsp

2.错误登录 login.jsp

3. 正确登录 login.jsp

4. 登录成功 success.jsp

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