javaweb实现登陆
用户登陆首页
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2020/6/4
Time: 19:05
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form method="POST" action="/login">
<div class="info">${error}</div>
<div class="form-group">
<label for="userName">userName</label>
<input id="userName" type="text" class="form-control" name="userName" value="" required autofocus>
</div>
<div class="form-group">
<label for="password">Password</label>
<input id="password" type="password" class="form-control" name="password" required data-eye>
</div>
<div class="form-group no-margin">
<button type="submit" class="btn btn-primary btn-block" >
Login
</button>
</div>
<%--<div class="margin-top20 text-center">
Don't have an account? <a href="register.html">Create One</a>
</div>--%>
</form>
</body>
</html>
用户类
package com.mrh.pojo**;
** /*
* @ClassName User
* @Description* TODO
* ** @Author m
* @Version 1.0
*/
* public class User {
private Integer id*;
** private String userName**;
** private String password**;
** @Override
public String toString() {
return “User{” +
“id=” + id +
“, userName=’” + userName + ‘’’ +
“, password=’” + password + ‘’’ +
‘}’**;
** }
public Integer getId() {
return id**;
** }
public void setId(Integer id) {
this.id = id**;
** }
public void setUserName(String userName) {
this.userName = userName**;
** }
public void setPassword(String password) {
this.password = password**;
** }
public String getUserName() {
return userName**;
** }
public String getPassword() {
return password**;
** }
}
用户基础类:
写了一个通过用户名返回查找到的用户的函数
package com.mrh.dao.user**;
** import com.mrh.dao.BaseDao**;
** import com.mrh.pojo.User**;
** import java.sql.ResultSet**;
** import java.sql.SQLException**;
** /*
* @ClassName UserDaoImp1
* @Description* TODO
* ** @Author m
* @Version 1.0
*/
* public class UserDaoImp1 implements UserDao {
/
*
* @param* userName
* ** @return 通过用户名查找用户*,*返回第一个查找到的用户
* ** @throws *SQLException
* **/
* public User getUser(String userName) throws SQLException {
String sql = "select * from user where username = ?"**;
** Object[] parm = {userName}**;
** BaseDao.connection();
** ResultSet res = BaseDao.query(sql,parm);
** User user = null**;
** while (res.next()){
user = new User();
** user.setId((Integer) res.getObject(“id”));
** user.setUserName((String) res.getObject(“username”));
** user.setPassword((String) res.getObject(“password”));
** }
BaseDao.close();
** return user;
** }
}
用户服务类
通过调用用户基础类与得到的用户密码比较，相同则返回该用户
package com.mrh.service**;
** import com.mrh.dao.user.UserDao**;
** import com.mrh.dao.user.UserDaoImp1**;
** import com.mrh.pojo.User**;
** import java.sql.SQLException**;
** /*
* @ClassName UserLogin
* @Description* *通过调用用户基础类与得到的用户密码比较，相同则返回该用户
* ** @Author m
* @Version 1.0
*/
* public class UserService {
UserDao userDao = new UserDaoImp1()**;
** public User userLogin(String userName**,** String password) throws SQLException {
User user = userDao.getUser(userName);
** if(user != null && user.getPassword().equals(password)){
return user;
** }else {
return null**;
** }
}
}
数据库连接基础类：
package com.mrh.dao;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
/**
* @ClassName BaseDao
* @Description TODO
* @Author m
* @Version 1.0
*/
public class BaseDao {
private static String driver;
private static String url;
private static String username;
private static String password;
//静态代码块，类加载的时候就初始化了
static {
Properties properties = new Properties();
//通过类加载器读取对应资源
InputStream inputStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
try {
properties.load(inputStream);
}catch (Exception e){
e.printStackTrace();
}
driver = properties.getProperty("driver");
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");
}
private static Connection con = null;
private static PreparedStatement preparedStatement = null;
private static ResultSet res = null;
public static Connection getCon() {
return con;
}
public static PreparedStatement getPreparedStatement() {
return preparedStatement;
}
public static ResultSet getRes() {
return res;
}
//数据库连接
public static void connection(){
try{
Class.forName(driver);
con = DriverManager.getConnection(url,username,password);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
//关闭数据库连接
public static void close(){
if(res != null){
try{
res.close();
} catch (SQLException throwable) {
throwable.printStackTrace();
}
}
if(preparedStatement != null){
try{
preparedStatement.close();
} catch (SQLException throwable) {
throwable.printStackTrace();
}
}
if(con != null){
try{
con.close();
} catch (SQLException throwable) {
throwable.printStackTrace();
}
}
}
//查询公共类
public static ResultSet query(String sql, Object[] parm) throws SQLException {
preparedStatement = con.prepareStatement(sql);
for (int i = 0; i < parm.length; i++) {
preparedStatement.setObject(i+1,parm[i]);
}
res = preparedStatement.executeQuery();
return res;
}
//update公共类
public static int update(String sql, Object[] parm) throws SQLException {
preparedStatement = con.prepareStatement(sql);
for (int i = 0; i < parm.length; i++) {
preparedStatement.setObject(i+1,parm[i]);
}
return preparedStatement.executeUpdate();
}
}
控制层loginServlet：
package com.mrh.servlet**;
** import com.mrh.pojo.User**;
** import com.mrh.service.UserService**;
** import javax.servlet.ServletException**;
** import javax.servlet.http.HttpServlet**;
** import javax.servlet.http.HttpServletRequest**;
** import javax.servlet.http.HttpServletResponse**;
** import java.io.IOException**;
** import java.sql.SQLException**;
** /*
* @ClassName loginServlet
* @Description* TODO
* ** @Author m
* @Version 1.0
*/
* public class loginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req*,** HttpServletResponse resp) throws ServletException**,** IOException {
//获取用户名和密码
String userName = req.getParameter(“userName”);
** String password = req.getParameter(“password”);
** UserService userService = new UserService();
** User user = null;
** try {
user = userService.userLogin(userName**,** password);
** } catch (SQLException throwables) {
throwables.printStackTrace();
** }
if(user == null){
//登陆失败，返回错误信息
req.setAttribute(“error”,“用户名或密码错误”);
** //转发到登陆界面，所以url不会变
req.getRequestDispatcher(“index.jsp”).forward(req,resp);
** }else {
resp.getWriter().write(“登陆成功”)**;
** }
}
@Override
protected void doPost(HttpServletRequest req**,** HttpServletResponse resp) throws ServletException**,** IOException {
doGet(req**,** resp)**;
** }
}