1.使用三层架构实现登录功能
2.dao层要对用用户输入的用户名的用户名进行校验
3.登录后跳转的网站的主页面，登录失败返回登录页面
项目结构图
Mysql创建数据库以及user表的创建
/*
SQLyog Ultimate v11.42 (64 bit)
MySQL - 8.0.20 : Database - userdata
*********************************************************************
*/
/*!40101 SET NAMES utf8 */;
/*!40101 SET SQL_MODE=''*/;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`userdata` /*!40100 DEFAULT CHARACTER SET utf8 */ /*!80016 DEFAULT ENCRYPTION='N' */;
USE `userdata`;
/*Table structure for table `user` */
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int NOT NULL AUTO_INCREMENT,
`username` varchar(20) NOT NULL,
`password` varchar(20) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
/*Data for the table `user` */
insert into `user`(`id`,`username`,`password`) values (1,'tom','123'),(2,'jru','456');
/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
1.编写登录页面
Login.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<style>
body{
margin: 0;
padding: 0;
font-family: sans-serif;
background: #34495e;
}
.box{
width: 300px;
padding: 40px;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
background: #191919;
text-align: center;
}
.box h1{
color: white;
text-transform: uppercase;
font-weight: 500;
}
.box input[type = "text"],.box input[type = "password"]{
border:0;
background: none;
display: block;
margin: 20px auto;
text-align: center;
border: 2px solid #3498db;
padding: 14px 10px;
width: 200px;
outline: none;
color: white;
border-radius: 24px;
transition: 0.25s;
}
.box input[type = "text"]:focus,.box input[type = "password"]:focus{
width: 280px;
border-color: #2ecc71;
}
.box input[type = "submit"]{
border:0;
background: none;
display: block;
margin: 20px auto;
text-align: center;
border: 2px solid #2ecc71;
padding: 14px 40px;
outline: none;
color: white;
border-radius: 24px;
transition: 0.25s;
cursor: poi
}
</style>
<body>
<form class="box" action="/userlogin/Login" method="post">
<h1>Login</h1>
<input type="text" name="username" placeholder="Username">
<input type="password" name="password" placeholder="Password">
<input type="submit" name="" value="Login">
<a href="register.html">SIGNUP</a>
</form>
</body>
</html>2.编写 controller
Login.Java
package com.yin.user.controller;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
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 com.yin.user.pojo.User;
import com.yin.user.service.UserService;
import com.yin.user.service.Impl.UserServiceImpl;
/**
* Servlet implementation class Login
*/
@WebServlet("/Login")
public class Login extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Login() {
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.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
User user = new User();
user.setUserName(username);
user.setPassword(password);
UserService userservice =new UserServiceImpl();
try {
int temp =userservice.Login(user);
if(temp>0){
RequestDispatcher rd =request.getRequestDispatcher("/index.html");
rd.forward(request, response);
}
else{
response.sendRedirect("/userlogin/Login.html");
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
3.编写service
UserService接口UserService.Java
package com.yin.user.service;
import com.yin.user.pojo.User;
public interface UserService {
int Login(User user) throws Exception;
}
接口UserService.java实现类
UserServiceImpl.java
package com.yin.user.service.Impl;
import com.yin.user.dao.userdao;
import com.yin.user.dao.impl.UserDaoImpl;
import com.yin.user.pojo.User;
import com.yin.user.service.UserService;
public class UserServiceImpl implements UserService {
@Override
public int Login(User user) throws Exception{
userdao userDao= new UserDaoImpl();
int t= userDao.Login(user);
return t;
}
}4.编写Dao
UserDao.java接口
package com.yin.user.dao;
import com.yin.user.pojo.User;
public interface userdao {
int register(User user)throws Exception;
int Login(User user) throws Exception;
}
UserDao.java接口的实现类 UserDaoImpl.java
package com.yin.user.dao.impl;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import com.yin.user.dao.userdao;
import com.yin.user.pojo.User;
public class UserDaoImpl implements userdao{
public int Login(User user) throws Exception{
int temp=0;
String sql ="select *from user where username=? and password=?";
Class.forName("com.mysql.cj.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/userdata",
"root", "yinge22");
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, user.getUserName());
ps.setString(2, user.getPassword());
ResultSet rs = ps.executeQuery();
if(rs.next()){
temp=1;
}
return temp;
}
}
