PHP设计模式之装饰者模式

定义：

装饰者模式就是不修改原类代码和继承的情况下动态扩展类的功能。传统的编程模式都是子类继承父类实现方法重载，使用装饰器模式，只需添加一个新的装饰器对象，更加灵活，避免类数量和层次过多。

角色：

Component（被装饰对象基类）

ConcreteComponent（具体被装饰对象）

Decorator（装饰者基类）

ContreteDecorator（具体的装饰者类）

示例代码：

//被装饰者基类

interface Component

{

public function operation();

}

//装饰者基类

abstract class Decorator implements Component

{

protected $component;

public function __construct(Component $component)

{

$this->component = $component;

}

public function operation()

{

$this->component->operation();

}

}

//具体装饰者类

class ConcreteComponent implements Component

{

public function operation()

{

echo 'do operation'.PHP_EOL;

}

}

//具体装饰类A

class ConcreteDecoratorA extends Decorator {

public function __construct(Component $component) {

parent::__construct($component);

}

public function operation() {

parent::operation();

$this->addedOperationA(); // 新增加的操作

}

public function addedOperationA() {

echo 'Add Operation A '.PHP_EOL;

}

}

//具体装饰类B

class ConcreteDecoratorB extends Decorator {

public function __construct(Component $component) {

parent::__construct($component);

}

public function operation() {

parent::operation();

$this->addedOperationB();

}

public function addedOperationB() {

echo 'Add Operation B '.PHP_EOL;

}

}

class Client {

public static function main() {

/*

do operation

Add Operation A

*/

$decoratorA = new ConcreteDecoratorA(new ConcreteComponent());

$decoratorA->operation();

/*

do operation

Add Operation A

Add Operation B

*/

$decoratorB = new ConcreteDecoratorB($decoratorA);

$decoratorB->operation();

}

}

Client::main();