PHP 示例

<?php
// PHP Hello World Examples

// 1. Basic Hello World
<?php
echo "Hello, World!";
?>

// 2. Hello World with variable
<?php
$message = "Hello, World!";
echo $message;
?>

// 3. Hello World with function
<?php
function sayHello() {
    return "Hello, World!";
}

echo sayHello();
?>

// 4. Hello World with parameters
<?php
function greet($name) {
    return "Hello, " . $name . "!";
}

echo greet("World");
echo greet("PHP");
?>

// 5. Hello World with class
<?php
class Greeter {
    private $message;

    public function __construct($message = "Hello, World!") {
        $this->message = $message;
    }

    public function greet() {
        return $this->message;
    }
}

$greeter = new Greeter();
echo $greeter->greet();
?>

// 6. Hello World with user input
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST['name'] ?? 'World';
    echo "Hello, " . htmlspecialchars($name) . "!";
} else {
?>
<form method="post" action="">
    Name: <input type="text" name="name">
    <input type="submit" value="Say Hello">
</form>
<?php
}
?>

// 7. Hello World with date and time
<?php
echo "Hello, World! Current time: " . date('Y-m-d H:i:s');
?>

// 8. Hello World multiple times
<?php
for ($i = 1; $i <= 5; $i++) {
    echo "Hello, World! $i<br>";
}
?>

// 9. Hello World in different languages
<?php
$greetings = [
    'en' => 'Hello, World!',
    'es' => '¡Hola, Mundo!',
    'fr' => 'Bonjour, le Monde!',
    'de' => 'Hallo, Welt!',
    'zh' => '你好，世界！',
    'ja' => 'こんにちは、世界！'
];

$lang = $_GET['lang'] ?? 'en';
echo $greetings[$lang] ?? $greetings['en'];
?>

// 10. Hello World with JSON response
<?php
header('Content-Type: application/json');

$response = [
    'message' => 'Hello, World!',
    'timestamp' => time(),
    'success' => true
];

echo json_encode($response, JSON_PRETTY_PRINT);
?>

// Basic data types examples
<?php
$integer = 42;
$float = 3.14;
$string = "Hello, PHP!";
$boolean = true;
$array = [1, 2, 3, 4, 5];
$associative = [
    'name' => 'John Doe',
    'age' => 30,
    'email' => '[email protected]'
];
$nullValue = null;

echo "Integer: $integer, Type: " . gettype($integer) . "<br>";
echo "Float: $float, Type: " . gettype($float) . "<br>";
echo "String: $string, Type: " . gettype($string) . "<br>";
echo "Boolean: " . ($boolean ? 'true' : 'false') . ", Type: " . gettype($boolean) . "<br>";
echo "Array: " . implode(', ', $array) . ", Type: " . gettype($array) . "<br>";
echo "Associative Array: " . print_r($associative, true) . ", Type: " . gettype($associative) . "<br>";

// Control flow examples
$age = 18;
if ($age >= 18) {
    echo "You are an adult<br>";
} else {
    echo "You are a minor<br>";
}

// Loop examples
$fruits = ['apple', 'banana', 'cherry'];
foreach ($fruits as $fruit) {
    echo "I like $fruit<br>";
}

// Array methods examples
$numbers = [1, 2, 3, 4, 5];
$squared = array_map(function($n) { return $n * $n; }, $numbers);
echo "Squared numbers: " . implode(', ', $squared);

// Superglobals examples
echo "Request Method: " . $_SERVER['REQUEST_METHOD'] . "<br>";
echo "Server Name: " . $_SERVER['SERVER_NAME'] . "<br>";
echo "Request URI: " . $_SERVER['REQUEST_URI'] . "<br>";

// Sessions example
<?php
session_start();
$_SESSION['message'] = 'Hello, Session World!';
echo $_SESSION['message'];
?>

<?php
// PHP Web Development Examples

// 1. Form Handling with Validation
<?php
$errors = [];
$success = '';

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $name = trim($_POST['name'] ?? '');
    $email = trim($_POST['email'] ?? '');
    $age = intval($_POST['age'] ?? 0);

    // Validation
    if (empty($name)) {
        $errors['name'] = 'Name is required';
    } elseif (strlen($name) < 2) {
        $errors['name'] = 'Name must be at least 2 characters';
    }

    if (empty($email)) {
        $errors['email'] = 'Email is required';
    } elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $errors['email'] = 'Invalid email format';
    }

    if ($age < 1 || $age > 120) {
        $errors['age'] = 'Age must be between 1 and 120';
    }

    if (empty($errors)) {
        // Process the valid data
        $success = "Form submitted successfully! Name: $name, Email: $email, Age: $age";

        // You could save to database here
        // saveUser($name, $email, $age);
    }
}
?>

<!DOCTYPE html>
<html>
<head>
    <title>PHP Form Validation</title>
</head>
<body>
    <?php if ($success): ?>
        <div style="color: green;"><?php echo htmlspecialchars($success); ?></div>
    <?php endif; ?>

    <?php if (!empty($errors)): ?>
        <div style="color: red;">
            <?php foreach ($errors as $error): ?>
                <div><?php echo htmlspecialchars($error); ?></div>
            <?php endforeach; ?>
        </div>
    <?php endif; ?>

    <form method="post">
        <div>
            <label>Name:</label>
            <input type="text" name="name" value="<?php echo htmlspecialchars($_POST['name'] ?? ''); ?>">
        </div>
        <div>
            <label>Email:</label>
            <input type="email" name="email" value="<?php echo htmlspecialchars($_POST['email'] ?? ''); ?>">
        </div>
        <div>
            <label>Age:</label>
            <input type="number" name="age" value="<?php echo htmlspecialchars($_POST['age'] ?? ''); ?>">
        </div>
        <button type="submit">Submit</button>
    </form>
</body>
</html>

// 2. Database Operations with PDO
<?php
class Database {
    private $pdo;

    public function __construct($host, $dbname, $username, $password) {
        try {
            $this->pdo = new PDO(
                "mysql:host=$host;dbname=$dbname;charset=utf8",
                $username,
                $password,
                [
                    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                    PDO::ATTR_EMULATE_PREPARES => false,
                ]
            );
        } catch (PDOException $e) {
            throw new Exception("Database connection failed: " . $e->getMessage());
        }
    }

    public function createUser($name, $email, $age) {
        $stmt = $this->pdo->prepare(
            "INSERT INTO users (name, email, age, created_at) VALUES (?, ?, ?, NOW())"
        );
        return $stmt->execute([$name, $email, $age]);
    }

    public function getUser($id) {
        $stmt = $this->pdo->prepare("SELECT * FROM users WHERE id = ?");
        $stmt->execute([$id]);
        return $stmt->fetch();
    }

    public function getAllUsers($limit = 10, $offset = 0) {
        $stmt = $this->pdo->prepare("SELECT * FROM users LIMIT ? OFFSET ?");
        $stmt->execute([$limit, $offset]);
        return $stmt->fetchAll();
    }

    public function updateUser($id, $name, $email, $age) {
        $stmt = $this->pdo->prepare(
            "UPDATE users SET name = ?, email = ?, age = ?, updated_at = NOW() WHERE id = ?"
        );
        return $stmt->execute([$name, $email, $age, $id]);
    }

    public function deleteUser($id) {
        $stmt = $this->pdo->prepare("DELETE FROM users WHERE id = ?");
        return $stmt->execute([$id]);
    }
}

// Usage example:
try {
    $db = new Database('localhost', 'myapp', 'username', 'password');

    // Create user
    $db->createUser('John Doe', '[email protected]', 30);

    // Get user
    $user = $db->getUser(1);
    if ($user) {
        echo "User: " . $user['name'];
    }

    // Get all users
    $users = $db->getAllUsers(10, 0);
    foreach ($users as $user) {
        echo $user['name'] . "<br>";
    }

} catch (Exception $e) {
    error_log($e->getMessage());
    echo "An error occurred. Please try again later.";
}
?>

// 3. REST API Implementation
<?php
header('Content-Type: application/json');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST, PUT, DELETE');
header('Access-Control-Allow-Headers: Content-Type');

class UserAPI {
    private $db;

    public function __construct() {
        $this->db = new Database('localhost', 'api_db', 'username', 'password');
    }

    public function handleRequest() {
        $method = $_SERVER['REQUEST_METHOD'];
        $path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
        $pathParts = explode('/', trim($path, '/'));

        try {
            switch ($method) {
                case 'GET':
                    return $this->handleGet($pathParts);
                case 'POST':
                    return $this->handlePost($pathParts);
                case 'PUT':
                    return $this->handlePut($pathParts);
                case 'DELETE':
                    return $this->handleDelete($pathParts);
                default:
                    http_response_code(405);
                    return ['error' => 'Method not allowed'];
            }
        } catch (Exception $e) {
            http_response_code(500);
            return ['error' => $e->getMessage()];
        }
    }

    private function handleGet($pathParts) {
        // GET /users - Get all users
        if (count($pathParts) == 1 && $pathParts[0] == 'users') {
            $users = $this->db->getAllUsers();
            return ['data' => $users];
        }

        // GET /users/{id} - Get specific user
        if (count($pathParts) == 2 && $pathParts[0] == 'users') {
            $id = intval($pathParts[1]);
            $user = $this->db->getUser($id);

            if (!$user) {
                http_response_code(404);
                return ['error' => 'User not found'];
            }

            return ['data' => $user];
        }

        http_response_code(404);
        return ['error' => 'Endpoint not found'];
    }

    private function handlePost($pathParts) {
        // POST /users - Create new user
        if (count($pathParts) == 1 && $pathParts[0] == 'users') {
            $input = json_decode(file_get_contents('php://input'), true);

            if (!$input || !isset($input['name']) || !isset($input['email'])) {
                http_response_code(400);
                return ['error' => 'Name and email are required'];
            }

            if ($this->db->createUser($input['name'], $input['email'], $input['age'] ?? null)) {
                http_response_code(201);
                return ['message' => 'User created successfully'];
            } else {
                http_response_code(500);
                return ['error' => 'Failed to create user'];
            }
        }

        http_response_code(404);
        return ['error' => 'Endpoint not found'];
    }

    private function handlePut($pathParts) {
        // PUT /users/{id} - Update user
        if (count($pathParts) == 2 && $pathParts[0] == 'users') {
            $id = intval($pathParts[1]);
            $input = json_decode(file_get_contents('php://input'), true);

            if (!$input || !isset($input['name']) || !isset($input['email'])) {
                http_response_code(400);
                return ['error' => 'Name and email are required'];
            }

            if ($this->db->updateUser($id, $input['name'], $input['email'], $input['age'] ?? null)) {
                return ['message' => 'User updated successfully'];
            } else {
                http_response_code(404);
                return ['error' => 'User not found'];
            }
        }

        http_response_code(404);
        return ['error' => 'Endpoint not found'];
    }

    private function handleDelete($pathParts) {
        // DELETE /users/{id} - Delete user
        if (count($pathParts) == 2 && $pathParts[0] == 'users') {
            $id = intval($pathParts[1]);

            if ($this->db->deleteUser($id)) {
                return ['message' => 'User deleted successfully'];
            } else {
                http_response_code(404);
                return ['error' => 'User not found'];
            }
        }

        http_response_code(404);
        return ['error' => 'Endpoint not found'];
    }
}

// Initialize and handle the request
$api = new UserAPI();
$response = $api->handleRequest();
echo json_encode($response, JSON_PRETTY_PRINT);
?>

// 4. File Upload Handling
<?php
class FileUploader {
    private $allowedTypes = ['image/jpeg', 'image/png', 'image/gif', 'application/pdf'];
    private $maxFileSize = 5 * 1024 * 1024; // 5MB
    private $uploadDir = 'uploads/';

    public function __construct() {
        if (!file_exists($this->uploadDir)) {
            mkdir($this->uploadDir, 0777, true);
        }
    }

    public function upload($fileKey) {
        if (!isset($_FILES[$fileKey])) {
            throw new Exception('No file uploaded');
        }

        $file = $_FILES[$fileKey];

        // Check for upload errors
        if ($file['error'] !== UPLOAD_ERR_OK) {
            throw new Exception('Upload error: ' . $this->getUploadErrorMessage($file['error']));
        }

        // Validate file type
        if (!in_array($file['type'], $this->allowedTypes)) {
            throw new Exception('File type not allowed');
        }

        // Validate file size
        if ($file['size'] > $this->maxFileSize) {
            throw new Exception('File too large');
        }

        // Generate unique filename
        $extension = pathinfo($file['name'], PATHINFO_EXTENSION);
        $filename = uniqid() . '.' . $extension;
        $filepath = $this->uploadDir . $filename;

        // Move uploaded file
        if (!move_uploaded_file($file['tmp_name'], $filepath)) {
            throw new Exception('Failed to move uploaded file');
        }

        return [
            'filename' => $filename,
            'filepath' => $filepath,
            'original_name' => $file['name'],
            'size' => $file['size'],
            'type' => $file['type']
        ];
    }

    private function getUploadErrorMessage($error) {
        switch ($error) {
            case UPLOAD_ERR_INI_SIZE:
                return 'The uploaded file exceeds the upload_max_filesize directive in php.ini';
            case UPLOAD_ERR_FORM_SIZE:
                return 'The uploaded file exceeds the MAX_FILE_SIZE directive in the HTML form';
            case UPLOAD_ERR_PARTIAL:
                return 'The uploaded file was only partially uploaded';
            case UPLOAD_ERR_NO_FILE:
                return 'No file was uploaded';
            case UPLOAD_ERR_NO_TMP_DIR:
                return 'Missing a temporary folder';
            case UPLOAD_ERR_CANT_WRITE:
                return 'Failed to write file to disk';
            case UPLOAD_ERR_EXTENSION:
                return 'A PHP extension stopped the file upload';
            default:
                return 'Unknown upload error';
        }
    }
}

// Usage example:
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    try {
        $uploader = new FileUploader();
        $result = $uploader->upload('file');
        echo json_encode(['success' => true, 'data' => $result]);
    } catch (Exception $e) {
        http_response_code(400);
        echo json_encode(['success' => false, 'error' => $e->getMessage()]);
    }
}
?>

<?php
// Modern PHP 8+ Features Examples

// 1. Typed Properties
class User {
    public int $id;
    public string $name;
    public string $email;
    private ?DateTime $createdAt = null;

    public function __construct(int $id, string $name, string $email) {
        $this->id = $id;
        $this->name = $name;
        $this->email = $email;
        $this->createdAt = new DateTime();
    }

    public function getCreatedAt(): ?DateTime {
        return $this->createdAt;
    }
}

$user = new User(1, 'John Doe', '[email protected]');
echo $user->name; // John Doe

// 2. Constructor Property Promotion (PHP 8.0)
class Product {
    public function __construct(
        private int $id,
        private string $name,
        private float $price,
        private array $categories = []
    ) {}

    public function getId(): int {
        return $this->id;
    }

    public function getName(): string {
        return $this->name;
    }

    public function getPrice(): float {
        return $this->price;
    }

    public function getCategories(): array {
        return $this->categories;
    }
}

$product = new Product(1, 'Laptop', 999.99, ['Electronics', 'Computers']);
echo $product->getName(); // Laptop

// 3. Union Types (PHP 8.0)
class Logger {
    public function log(string|int $message): void {
        echo $this->formatMessage($message);
    }

    private function formatMessage(string|int $message): string {
        return "Log: " . (string) $message;
    }
}

$logger = new Logger();
$logger->log("Hello, World!");
$logger->log(42);

// 4. Named Arguments (PHP 8.0)
class EmailService {
    public function sendEmail(
        string $to,
        string $subject,
        string $body,
        string $from = '[email protected]',
        array $cc = [],
        array $bcc = []
    ): bool {
        echo "Sending email to: $to
";
        echo "Subject: $subject
";
        echo "Body: $body
";
        echo "From: $from
";
        if (!empty($cc)) echo "CC: " . implode(', ', $cc) . "
";
        if (!empty($bcc)) echo "BCC: " . implode(', ', $bcc) . "
";
        return true;
    }
}

$email = new EmailService();
// Using named arguments
$email->sendEmail(
    to: '[email protected]',
    subject: 'Welcome!',
    body: 'Thank you for joining our platform.',
    cc: ['[email protected]']
);

// 5. Match Expressions (PHP 8.0)
class HttpStatus {
    public function getMessage(int $code): string {
        return match ($code) {
            200 => 'OK',
            201 => 'Created',
            204 => 'No Content',
            400 => 'Bad Request',
            401 => 'Unauthorized',
            403 => 'Forbidden',
            404 => 'Not Found',
            500 => 'Internal Server Error',
            default => 'Unknown Status'
        };
    }

    public function isSuccess(int $code): bool {
        return match (true) {
            $code >= 200 && $code < 300 => true,
            default => false
        };
    }
}

$status = new HttpStatus();
echo $status->getMessage(200); // OK
echo $status->isSuccess(404) ? 'Success' : 'Error'; // Error

// 6. Nullsafe Operator (PHP 8.0)
class Address {
    public function __construct(public ?string $city = null) {}
}

class User {
    public function __construct(public ?Address $address = null) {}

    public function getCity(): ?string {
        return $this->address?->city;
    }

    // Before PHP 8.0 (without nullsafe operator):
    public function getCityOld(): ?string {
        return $this->address ? $this->address->city : null;
    }
}

$user = new User();
echo $user->getCity() ?? 'Unknown City'; // Unknown City

$userWithAddress = new User(new Address('New York'));
echo $userWithAddress->getCity() ?? 'Unknown City'; // New York

// 7. Attributes (PHP 8.0)
#[Attribute]
class Route {
    public function __construct(
        public string $path,
        public string $method = 'GET'
    ) {}
}

class UserController {
    #[Route('/users', 'GET')]
    public function index(): array {
        return ['users' => []];
    }

    #[Route('/users/{id}', 'GET')]
    public function show(int $id): array {
        return ['user' => ['id' => $id]];
    }

    #[Route('/users', 'POST')]
    public function store(): array {
        return ['message' => 'User created'];
    }
}

// 8. Enums (PHP 8.1)
enum UserRole: string {
    case ADMIN = 'admin';
    case EDITOR = 'editor';
    case USER = 'user';

    public function getPermissions(): array {
        return match ($this) {
            self::ADMIN => ['create', 'read', 'update', 'delete'],
            self::EDITOR => ['create', 'read', 'update'],
            self::USER => ['read'],
        };
    }
}

class AuthUser {
    public function __construct(
        private string $name,
        private UserRole $role
    ) {}

    public function can(string $permission): bool {
        return in_array($permission, $this->role->getPermissions());
    }
}

$admin = new AuthUser('Admin User', UserRole::ADMIN);
echo $admin->can('delete') ? 'Yes' : 'No'; // Yes

// 9. Readonly Properties (PHP 8.1)
class ProductConfig {
    public function __construct(
        public readonly string $name,
        public readonly float $price,
        public readonly array $features
    ) {}

    public function getInfo(): array {
        return [
            'name' => $this->name,
            'price' => $this->price,
            'features' => $this->features
        ];
    }
}

// $config = new ProductConfig('Premium Plan', 29.99, ['Feature 1', 'Feature 2']);
// $config->name = 'Cannot modify readonly property';

// 10. Fibers (PHP 8.1) - Basic Async Support
use Fiber;

class AsyncTask {
    private Fiber $fiber;

    public function __construct(callable $callback) {
        $this->fiber = new Fiber($callback);
    }

    public function start(...$args): mixed {
        return $this->fiber->start(...$args);
    }

    public function resume(mixed $value = null): mixed {
        return $this->fiber->resume($value);
    }
}

// Example async task
function fetchUrl(string $url): string {
    echo "Starting fetch from $url
";

    // Simulate async operation
    Fiber::suspend('waiting...');

    echo "Completed fetch from $url
";
    return "Content from $url";
}

$task = new AsyncTask('fetchUrl');
$result = $task->start('https://api.example.com');

// Resume the fiber
$content = $task->resume();
echo $content;

// 11. Modern Array Functions
class ArrayHelper {
    public static function filterMap(array $array, callable $filter, callable $map): array {
        return array_map($map, array_filter($array, $filter));
    }

    public static function first(array $array, ?callable $callback = null): mixed {
        if ($callback === null) {
            return empty($array) ? null : $array[0];
        }

        foreach ($array as $value) {
            if ($callback($value)) {
                return $value;
            }
        }

        return null;
    }
}

$numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// Filter even numbers and square them
$evenSquares = ArrayHelper::filterMap(
    $numbers,
    fn($n) => $n % 2 === 0,
    fn($n) => $n ** 2
);

print_r($evenSquares); // [4, 16, 36, 64, 100]

// 12. Modern Error Handling with Exceptions
class ValidationException extends Exception {
    private array $errors;

    public function __construct(array $errors) {
        $this->errors = $errors;
        parent::__construct('Validation failed');
    }

    public function getErrors(): array {
        return $this->errors;
    }
}

class RequestValidator {
    public function validate(array $data): void {
        $errors = [];

        if (empty($data['name'] ?? '')) {
            $errors['name'] = 'Name is required';
        }

        if (!filter_var($data['email'] ?? '', FILTER_VALIDATE_EMAIL)) {
            $errors['email'] = 'Valid email is required';
        }

        if (!empty($errors)) {
            throw new ValidationException($errors);
        }
    }
}

try {
    $validator = new RequestValidator();
    $validator->validate([
        'name' => '',
        'email' => 'invalid-email'
    ]);
} catch (ValidationException $e) {
    echo "Validation errors: " . implode(', ', $e->getErrors());
}