PHP 常见设计模式及示例

<?php
// 装饰器模式示例
interface Component {
    public function operation();
}
 
class ConcreteComponent implements Component {
    public function operation() {
        echo "具体对象的操作方法。\n";
    }
}
 
abstract class Decorator implements Component {
    protected $component;
 
    public function __construct(Component $component) {
        $this->component = $component;
    }
}
 
class ConcreteDecoratorA extends Decorator {
    public function operation() {
        $this->component->operation();
        $this->addedState = "新增状态A";
        $this->addedBehavior();
    }
 
    private $addedState;
 
    private function addedBehavior() {
        echo "具体装饰类A的操作方法。\n";
    }
}
 
class ConcreteDecoratorB extends Decorator {
    public function operation() {
        $this->component->operation();
        $this->addedState = "新增状态B";
        $this->addedBehavior();
    }
 
    private $addedState;
 
    private function addedBehavior() {
        echo "具体装饰类B的操作方法。\n";
    }
}
 
// 使用示例
$component = new ConcreteComponent();
$decoratorA = new ConcreteDecoratorA($component);
$decoratorB = new ConcreteDecoratorB($decoratorA);
 
$decoratorB->operation(); // 输出装饰后的操作结果
?>

这个示例代码展示了如何在PHP中实现装饰器模式。首先定义了一个Component接口和一个ConcreteComponent类，这是被装饰的基础组件。然后定义了一个抽象的Decorator类，用于保存对Component的引用。接着定义了两个具体的装饰类ConcreteDecoratorA和ConcreteDecoratorB，它们在基础操作的基础上添加了额外的状态和行为。最后，我们创建了一个ConcreteComponent对象，并给它加上了装饰，并调用了最终装饰后的operation方法。