简单的HTML+Servlet+JDBC登录案例
HTML+Servlet+JDBC登录案例
思路
我们发现：所有的代码：接收请求、查询数据库、封装对象、作出响应的代码都在Servlet中实现，这不符合程序的单一职责原则。应该将各自的代码抽取成各自的类。即
Servlet【控制层】 只做接收请求，做出响应
Dao【数据访问层】只做数据库操作
Service【业务层】只做业务逻辑，判断和数据的处理
这就是三层架构
搭建项目框架
1、创建三层架构的包
2、创建数据库
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) DEFAULT NULL,
`password` varchar(255) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`address` varchar(255) DEFAULT NULL,
`phone` varchar(255) DEFAULT NULL,
`birthday` date DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
3、创建实体类
package com.lyc.pojo;
import java.sql.Date;
public class User {
private int id;
private String username;
private String password;
private int age;
private String address;
private String phone;
private Date birthday;
public User() {
}
public User(int id, String username, String password, int age, String address, String phone, Date birthday) {
this.id = id;
this.username = username;
this.password = password;
this.age = age;
this.address = address;
this.phone = phone;
this.birthday = birthday;
}
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;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", age=" + age +
", address='" + address + '\'' +
", phone='" + phone + '\'' +
", birthday=" + birthday +
'}';
}
}
4、创建JDBC工具类
package com.lyc.utils;
import java.sql.*;
public class DBUtil {
private static Connection conn = null;
private static final String URL = "jdbc:mysql://localhost:3306/test";
private static final String USERNAME = "root";
private static final String PASSWORD = "******";
static {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static Connection getConnection(){
try {
conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static void closeAll(Connection conn, PreparedStatement ps){
try {
ps.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void closeAll(Connection conn, PreparedStatement ps, ResultSet rs){
try {
rs.close();
ps.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
5、登录页面
<%--
Created by IntelliJ IDEA.
User: ASUS
Date: 2022/9/2
Time: 18:52
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录title>
head>
<body>
<form action="LoginServlet" method="post">
<table border="1" style="text-align: center">
<tr>
<td> 用户名:td>
<td>
<input type="text" name="username">
td>
tr>
<tr>
<td> 密码:td>
<td>
<input type="password" name="password">
td>
tr>
<tr>
<td colspan="2">
<input type="submit" value="登录">
<input type="reset">
td>
tr>
table>
form>
body>
html>
6、配置web.xml文件
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>LoginServletservlet-name>
<servlet-class>com.lyc.servlet.LoginServletservlet-class>
servlet>
<servlet-mapping>
<servlet-name>LoginServletservlet-name>
<url-pattern>/LoginServleturl-pattern>
servlet-mapping>
web-app>
7、编写Servlet程序
package com.lyc.servlet;
import com.lyc.pojo.User;
import com.lyc.service.impl.LoginServiceImpl;
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("/LoginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
String username = req.getParameter("username");
String password = req.getParameter("password");
LoginServiceImpl service = new LoginServiceImpl();
User user = service.login(username, password);
if(user != null){
req.getRequestDispatcher("/FindAllServlet").forward(req,resp);
} else{
req.getRequestDispatcher("/fail.jsp").forward(req,resp);
}
}
}
8、编写Service和ServiceImpl
先写接口方法
package com.lyc.service;
import com.lyc.pojo.User;
public interface LoginService {
User login(String username, String password);
}
再实现该接口方法
package com.lyc.service.impl;
import com.lyc.dao.impl.LoginDaoImpl;
import com.lyc.pojo.User;
import com.lyc.service.LoginService;
public class LoginServiceImpl implements LoginService {
@Override
public User login(String username, String password) {
LoginDaoImpl loginDao = new LoginDaoImpl();
User user = loginDao.login(username, password);
return user;
}
}
9、编写Dao和DaoImpl
先写接口
package com.lyc.dao;
import com.lyc.pojo.User;
public interface LoginDao {
User login(String username, String password);
}
再实现该接口
package com.lyc.dao.impl;
import com.lyc.dao.LoginDao;
import com.lyc.pojo.User;
import com.lyc.utils.DBUtil;
import java.sql.*;
public class LoginDaoImpl implements LoginDao {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
User user = null;
@Override
public User login(String username, String password) {
conn = DBUtil.getConnection();
String sql = "select * from user where username=? and password = ?";
try {
ps = conn.prepareStatement(sql);
ps.setString(1,username);
ps.setString(2,password);
rs = ps.executeQuery();
if (rs.next()){
int id = rs.getInt("id");
String sqluser = rs.getString("username");
String sqlpwd = rs.getString("password");
int age = rs.getInt("age");
String address = rs.getString("address");
String phone = rs.getString("phone");
Date birthday = rs.getDate("birthday");
user = new User(id,sqluser,sqlpwd,age,address,phone,birthday);
}
} catch (SQLException e) {
e.printStackTrace();
}finally {
DBUtil.closeAll(conn,ps,rs);
}
return user;
}
}
整个项目的框架结构
