基于PHP和MySQL的用户登录注册系统实现

系统架构

系统采用前后端分离的架构，使用PHP作为后端语言，MySQL作为数据库。以下是系统的整体架构图：

这个架构图展示了系统的三个主要层次：

前端界面层：包含用户交互的三个页面（注册、登录和欢迎页面）
后端服务层：处理用户请求的PHP处理器和管理用户会话的组件
数据库层：使用MySQL存储用户信息

当用户进行注册或登录操作时，数据会从前端界面传递到PHP处理器，经过验证后存储到MySQL数据库中。会话管理确保用户登录状态的维护，成功登录后显示欢迎页面。

数据库设计

首先，我们需要创建一个存储用户信息的数据库表。以下是表结构：

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL,
    email VARCHAR(100) NOT NULL,
    password VARCHAR(255) NOT NULL,
    UNIQUE KEY (email)
);

后端实现

数据库连接文件（db.php）：

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "user_system";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
?>

注册页面（register.php）：

<?php
session_start();
include 'db.php';

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = $_POST['username'];
    $email = $_POST['email'];
    $password = $_POST['password'];
    
    // 检查邮箱是否已存在
    $stmt = $conn->prepare("SELECT email FROM users WHERE email = ?");
    $stmt->bind_param("s", $email);
    $stmt->execute();
    $stmt->store_result();
    
    if ($stmt->num_rows > 0) {
        $error = "该邮箱已被使用";
    } else {
        // 插入新用户
        $stmt = $conn->prepare("INSERT INTO users (username, email, password) VALUES (?, ?, ?)");
        $stmt->bind_param("sss", $username, $email, $password);
        
        if ($stmt->execute()) {
            header("Location: login.php");
            exit();
        } else {
            $error = "注册失败，请重试";
        }
    }
    $stmt->close();
}
?>

登录页面（login.php）：

<?php
session_start();
include 'db.php';

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $email = $_POST['email'];
    $password = $_POST['password'];
    
    $stmt = $conn->prepare("SELECT id, username FROM users WHERE email = ? AND password = ?");
    $stmt->bind_param("ss", $email, $password);
    $stmt->execute();
    $result = $stmt->get_result();
    
    if ($result->num_rows == 1) {
        $user = $result->fetch_assoc();
        $_SESSION['user_id'] = $user['id'];
        $_SESSION['username'] = $user['username'];
        header("Location: welcome.php");
        exit();
    } else {
        $error = "邮箱或密码错误";
    }
    $stmt->close();
}
?>

欢迎页面（welcome.php）：

<?php
session_start();
include 'db.php';

if (!isset($_SESSION['user_id'])) {
    header("Location: login.php");
    exit();
}

$username = $_SESSION['username'];
?>

HTML界面

注册页面HTML：

<!DOCTYPE html>
<html>
<head>
    <title>用户注册</title>
    <style>
        .container {
            width: 300px;
            margin: 50px auto;
            padding: 20px;
            border: 1px solid #ccc;
        }
        .error {
            color: red;
            margin-bottom: 10px;
        }
    </style>
</head>
<body>
    <div class="container">
        <h2>用户注册</h2>
        <?php if(isset($error)): ?>
            <div class="error"><?php echo $error; ?></div>
        <?php endif; ?>
        <form action="" method="post">
            <div>
                <label>用户名：</label>
                <input type="text" name="username" required>
            </div>
            <div>
                <label>邮箱：</label>
                <input type="email" name="email" required>
            </div>
            <div>
                <label>密码：</label>
                <input type="password" name="password" required>
            </div>
            <button type="submit">注册</button>
        </form>
        <p>已有账号？<a href="login.php">登录</a></p>
    </div>
</body>
</html>

登录页面HTML：

<!DOCTYPE html>
<html>
<head>
    <title>用户登录</title>
    <style>
        .container {
            width: 300px;
            margin: 50px auto;
            padding: 20px;
            border: 1px solid #ccc;
        }
        .error {
            color: red;
            margin-bottom: 10px;
        }
    </style>
</head>
<body>
    <div class="container">
        <h2>用户登录</h2>
        <?php if(isset($error)): ?>
            <div class="error"><?php echo $error; ?></div>
        <?php endif; ?>
        <form action="" method="post">
            <div>
                <label>邮箱：</label>
                <input type="email" name="email" required>
            </div>
            <div>
                <label>密码：</label>
                <input type="password" name="password" required>
            </div>
            <button type="submit">登录</button>
        </form>
        <p>没有账号？<a href="register.php">注册</a></p>
    </div>
</body>
</html>

欢迎页面HTML：

<!DOCTYPE html>
<html>
<head>
    <title>欢迎页面</title>
</head>
<body>
    <div style="text-align: center; margin-top: 50px;">
        <h2>欢迎您，<?php echo htmlspecialchars($username); ?>！</h2>
        <p><a href="logout.php">退出登录</a></p>
    </div>
</body>
</html>