基于Servlet实现简单系统登录

一、需求

1.实现分层架构：bean dao service controller层
2.基于Servlet实现controller：登录成功进入欢迎页面；登录失败重新登录，并显示上次的登录用户名
3.前端：登录页面login.jsp 欢迎页面success.jsp

二、项目结构

bean层

User.java

package bean;

public class User {
    private int id;
    private String pwd;
    private String nickname;
    private String addr;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public String getNickname() {
        return nickname;
    }
    public void setNickname(String nickname) {
        this.nickname = nickname;
    }
    public String getAddr() {
        return addr;
    }
    public void setAddr(String addr) {
        this.addr = addr;
    }
    public User(int id, String pwd, String nickname, String addr) {
        super();
        this.id = id;
        this.pwd = pwd;
        this.nickname = nickname;
        this.addr = addr;
    }
    public User() {
        super();        
    }
    
}

dao层

UserDAO.java

package dao;

import bean.User;

public interface UserDAO {
    User selectUserById(int id);
}

UserDaoImpl.java

package dao;

import bean.User;

public class UserDaoImpl implements UserDAO {

    @Override
    public User selectUserById(int id) {
        if(id==1) {
            return new User(1,"123456","张三","山东烟台市莱山区");
        } else {
            return null;
        }    
        
    }
}

 

service层

UserService.java

package service;

import bean.User;

public interface UserService {
    boolean login(User user);
}

UserServiceImpl.java

package service;

import bean.User;
import dao.UserDAO;

public class UserServiceImpl implements UserService{
    private UserDAO dao;
    public UserServiceImpl(UserDAO dao) {
        this.dao = dao;
    }
    @Override
    public boolean login(User user) {
        User userDB=dao.selectUserById(user.getId());        
        if(userDB!=null && userDB.getPwd().contentEquals(user.getPwd())) {
            user.setNickname(userDB.getNickname());
            user.setAddr(userDB.getAddr());
            return true;
        }else
            return false;
    }

}

 

controller层

checkLogin.java

检测登录情况

package controller; import java.io.IOException; 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 bean.User; import dao.UserDaoImpl; import service.UserService; import service.UserServiceImpl; /** * Servlet implementation class checkLogin */ @WebServlet("/checkLogin") public class checkLogin extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public checkLogin() { super(); // TODO Auto-generated constructor stub  } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub response.getWriter().append("Served at: ").append(request.getContextPath()); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1处理请求参数 //2调用service进行处理 //3根据处理结果，重定向转发到Servlet jsp request.setCharacterEncoding("utf-8"); String id=request.getParameter("name"); String pwd = request.getParameter("pwd"); UserService service = new UserServiceImpl(new UserDaoImpl()); User user=new User(); user.setId(Integer.parseInt(id)); user.setPwd(pwd); if(service.login(user))//密码验证 登录成功进入欢迎页面  { request.setAttribute("user",user.getNickname()); request.getRequestDispatcher("\\success.jsp").forward(request, response); } else//登录失败重新登录，并显示上次的登录用户名  { request.setAttribute("name",user.getNickname()); request.getRequestDispatcher("\\login.jsp").forward(request, response); } } }

 

前端

login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>登录页面</title> </head> <body> <form method="post" action=checkLogin> <table> <tr> <td>输入用户名：</td> <td><input type="text" name="name" value=<%=request.getAttribute("user") %>> </td> </tr> <tr> <td>输入密码：</td> <td><input type="password" name="pwd" value=<%=request.getParameter("pwd")%>> </td> </tr> <tr > <td colspan=2><input type="submit" value="登录"></td> </tr> </table> </form> </body> </html>

 

success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@page import="java.util.*,bean.*"%>> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>欢迎页面</title> </head> <body> <h1>登录成功</h1> <h2> 欢迎您！<%=request.getAttribute("user")%> </h2> </body> </html>