PHP面向对象怎么实现_PHP面向对象编程基础与实例教程

<?php

// 定义一个Car类
class Car {
    // 属性（特性），使用public修饰符表示可公开访问
    public $brand;
    public $color;
    public $year;

    // 方法（行为），构造函数，在创建对象时自动调用
    public function __construct($brand, $color, $year) {
        $this->brand = $brand; // $this 指向当前对象实例
        $this->color = $color;
        $this->year = $year;
        echo "A new " . $this->year . " " . $this->brand . " " . $this->color . " car is created.<br>";
    }

    // 普通方法
    public function startEngine() {
        return $this->brand . " engine started!<br>";
    }

    public function drive() {
        return "The " . $this->color . " " . $this->brand . " is driving.<br>";
    }

    // 析构函数，对象销毁时自动调用
    public function __destruct() {
        echo "The " . $this->brand . " car object is destroyed.<br>";
    }
}

// 创建Car类的对象（实例化）
$myCar = new Car("Toyota", "Red", 2022);
$anotherCar = new Car("Honda", "Blue", 2023);

// 访问对象的属性
echo "My car is a " . $myCar->year . " " . $myCar->brand . " of " . $myCar->color . " color.<br>";

// 调用对象的方法
echo $myCar->startEngine();
echo $anotherCar->drive();

// 当脚本执行完毕，或者对象不再被引用时，析构函数会被调用
// unset($myCar); // 可以手动销毁对象
?>

<?php
class Account {
    public $accountNumber;
    private $balance; // 余额是私有的，不能直接从外部访问
    protected $ownerName; // 账户所有者信息，子类可以访问

    public function __construct($number, $initialBalance, $owner) {
        $this->accountNumber = $number;
        $this->balance = $initialBalance;
        $this->ownerName = $owner;
    }

    // 公共方法来存钱
    public function deposit($amount) {
        if ($amount > 0) {
            $this->balance += $amount;
            echo "Deposited " . $amount . ". New balance: " . $this->balance . "<br>";
        }
    }

    // 公共方法来取钱
    public function withdraw($amount) {
        if ($amount > 0 && $this->balance >= $amount) {
            $this->balance -= $amount;
            echo "Withdrew " . $amount . ". New balance: " . $this->balance . "<br>";
            return true;
        }
        echo "Insufficient funds or invalid amount for withdrawal.<br>";
        return false;
    }

    // 公共方法来获取余额，外部不能直接访问$balance
    public function getBalance() {
        return $this->balance;
    }
}

$myAccount = new Account("12345", 1000, "Alice");
// echo $myAccount->balance; // 这会报错，因为$balance是private的
echo "Current balance: " . $myAccount->getBalance() . "<br>";
$myAccount->deposit(500);
$myAccount->withdraw(200);
?>

<?php
class Animal {
    protected $name;

    public function __construct($name) {
        $this->name = $name;
    }

    public function eat() {
        return $this->name . " is eating.<br>";
    }

    public function sleep() {
        return $this->name . " is sleeping.<br>";
    }
}

class Dog extends Animal { // Dog继承Animal
    public function bark() {
        return $this->name . " says Woof!<br>";
    }

    // 重写父类的eat方法
    public function eat() {
        return $this->name . " is eating dog food.<br>";
    }
}

class Cat extends Animal { // Cat继承Animal
    public function meow() {
        return $this->name . " says Meow!<br>";
    }
}

$dog = new Dog("Buddy");
echo $dog->eat();   // 调用重写后的方法
echo $dog->sleep(); // 调用继承的方法
echo $dog->bark();

$cat = new Cat("Whiskers");
echo $cat->eat();
echo $cat->meow();
?>

<?php
// 定义一个PaymentMethod接口
interface PaymentMethod {
    public function pay($amount);
}

// 实现PaymentMethod接口的CreditCard类
class CreditCard implements PaymentMethod {
    public function pay($amount) {
        return "Paid " . $amount . " via Credit Card.<br>";
    }
}

// 实现PaymentMethod接口的PayPal类
class PayPal implements PaymentMethod {
    public function pay($amount) {
        return "Paid " . $amount . " via PayPal.<br>";
    }
}

// 一个处理支付的函数，接受任何实现PaymentMethod接口的对象
function processPayment(PaymentMethod $method, $amount) {
    echo $method->pay($amount);
}

$creditCard = new CreditCard();
$payPal = new PayPal();

processPayment($creditCard, 100);
processPayment($payPal, 50);
?>

<?php
abstract class Logger {
    protected $logFile;

    public function __construct($logFile) {
        $this->logFile = $logFile;
    }

    // 具体方法：所有日志器都可能需要获取日志文件路径
    public function getLogFilePath() {
        return $this->logFile;
    }

    // 抽象方法：具体如何写入日志，留给子类实现
    abstract public function writeLog($message);
}

class FileLogger extends Logger {
    public function writeLog($message) {
        file_put_contents($this->logFile, date('Y-m-d H:i:s') . " - " . $message . PHP_EOL, FILE_APPEND);
        echo "Logged to file: " . $message . "<br>";
    }
}

class ConsoleLogger extends Logger {
    public function writeLog($message) {
        echo "Logged to console: " . $message . "<br>";
    }
}

// $logger = new Logger("app.log"); // 错误：不能实例化抽象类

$fileLogger = new FileLogger("app.log");
$fileLogger->writeLog("User logged in.");

$consoleLogger = new ConsoleLogger("ignored.log"); // logFile在这里可能不重要，但构造函数要求
$consoleLogger->writeLog("Application started.");
?>