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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" %> <html> <head> <title>$Title$</title> </head> <body> <a href="login.jsp">登录</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>登录</title>
<style>
#msg {
color: red;
}
</style>
</head>
<body>
<form action="user" method="post">
账号：<input type="text" name="userName"><span id="msg"><%=request.getAttribute("msg")%></span>
密码：<input type="text" name="passWord">
<input type="hidden" name="method" value="login">
<input type="submit" value="登录">
</form>
</body>
</html>3) web >> success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ page import="constant.Con" %> <html> <head> <title>用户中心</title> </head> <body> <%=request.getSession().getAttribute(Con.USER)%><h2 >欢迎您</h2> <a href="login.html">返回重新登录</a> </body> </html>
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.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<User> 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<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) {
// 发送sql语句对象
PreparedStatement statement = null;
List<User> 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);
}
}
}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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