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php 多态的实现

2026-02-16 06:42:03PHP

PHP 多态的实现方式

PHP 通过面向对象编程的特性支持多态，主要依赖继承、接口和抽象类实现。以下是具体实现方法：

通过继承实现多态

子类重写父类方法，调用时根据对象类型执行不同逻辑：

class Animal {
    public function makeSound() {
        echo "Animal sound";
    }
}

class Dog extends Animal {
    public function makeSound() {
        echo "Bark";
    }
}

class Cat extends Animal {
    public function makeSound() {
        echo "Meow";
    }
}

function animalSound(Animal $animal) {
    $animal->makeSound();
}

$dog = new Dog();
$cat = new Cat();
animalSound($dog); // 输出: Bark
animalSound($cat); // 输出: Meow

通过接口实现多态

定义接口规范行为，不同类实现相同接口但逻辑不同：

interface Shape {
    public function calculateArea();
}

class Circle implements Shape {
    private $radius;

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

    public function calculateArea() {
        return pi() * pow($this->radius, 2);
    }
}

class Square implements Shape {
    private $side;

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

    public function calculateArea() {
        return pow($this->side, 2);
    }
}

function printArea(Shape $shape) {
    echo $shape->calculateArea();
}

$circle = new Circle(3);
$square = new Square(4);
printArea($circle); // 输出: 28.274...
printArea($square); // 输出: 16

通过抽象类实现多态

抽象类定义部分实现，子类完成具体行为：

abstract class Vehicle {
    abstract public function drive();
}

class Car extends Vehicle {
    public function drive() {
        echo "Driving a car";
    }
}

class Bike extends Vehicle {
    public function drive() {
        echo "Riding a bike";
    }
}

function testDrive(Vehicle $vehicle) {
    $vehicle->drive();
}

$car = new Car();
$bike = new Bike();
testDrive($car);  // 输出: Driving a car
testDrive($bike); // 输出: Riding a bike

类型提示与多态

PHP 的类型提示（Type Hinting）允许在参数中指定接口或父类，实际传入的子类对象会自动匹配：

function processPayment(PaymentGateway $gateway) {
    $gateway->process();
}

此方法兼容所有实现 PaymentGateway 接口的类。

动态特性实现多态

PHP 的动态特性允许运行时决定调用方法：

class DynamicExample {
    public function handle($type) {
        $method = 'handle' . ucfirst($type);
        if (method_exists($this, $method)) {
            $this->$method();
        }
    }

    private function handleA() {
        echo "Handling type A";
    }

    private function handleB() {
        echo "Handling type B";
    }
}

$obj = new DynamicExample();
$obj->handle('A'); // 输出: Handling type A
$obj->handle('B'); // 输出: Handling type B