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php 实现多态

2026-02-27 15:25:01PHP

多态的概念

多态是面向对象编程的三大特性之一（封装、继承、多态），指同一个方法在不同类中有不同的实现方式。PHP 通过继承和接口实现多态。

通过继承实现多态

子类可以重写父类的方法，调用时根据对象类型执行对应的方法。

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";
    }
}

$animals = [new Dog(), new Cat()];
foreach ($animals as $animal) {
    $animal->makeSound(); // 输出 Bark 和 Meow
}

通过接口实现多态

接口定义方法规范，不同类实现接口并提供具体逻辑。

interface Shape {
    public function calculateArea();
}

class Circle implements Shape {
    private $radius;

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

    public function calculateArea() {
        return 3.14 * $this->radius * $this->radius;
    }
}

class Square implements Shape {
    private $side;

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

    public function calculateArea() {
        return $this->side * $this->side;
    }
}

$shapes = [new Circle(5), new Square(4)];
foreach ($shapes as $shape) {
    echo $shape->calculateArea(); // 输出圆的面积和正方形的面积
}

抽象类实现多态

抽象类结合了接口和继承的特性，可以定义抽象方法和具体方法。

abstract class Vehicle {
    abstract public function drive();

    public function startEngine() {
        echo "Engine started";
    }
}

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

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

$vehicles = [new Car(), new Bike()];
foreach ($vehicles as $vehicle) {
    $vehicle->drive(); // 输出 Driving a car 和 Riding a bike
}