装饰器模式又叫装饰者模式。装饰模式是在不必改变原类文件和使用继承的情况下，动态地扩展一个对象的功能。它是通过创建一个包装对象，也就是装饰来包裹真实的对象。 ``` <?php /** * 输出一个字符串 * 装饰器动态添加功能 * Class EchoText */ class EchoText { protected $decorator = []; public function Index() { //调用装饰器前置操作 $this->beforeEcho(); echo "你好，我是装饰器。"; //调用装饰器后置操作 $this->afterEcho(); } //增加装饰器 public function addDecorator(Decorator $decorator) { $this->decorator[] = $decorator; } //执行装饰器前置操作 先进先出原则 protected function beforeEcho() { foreach ($this->decorator as $decorator) $decorator->before(); } //执行装饰器后置操作 先进后出原则 protected function afterEcho() { $tmp = array_reverse($this->decorator); foreach ($tmp as $decorator) $decorator->after(); } } /** * 装饰器接口 * Class Decorator */ interface Decorator { public function before(); public function after(); } /** * 颜色装饰器实现 * Class ColorDecorator */ class ColorDecorator implements Decorator { protected $color; public function __construct($color) { $this->color = $color; } public function before() { echo "<dis style='color: {$this->color}'>"; } public function after() { echo "</div>"; } } /** * 字体大小装饰器实现 * Class SizeDecorator */ class SizeDecorator implements Decorator { protected $size; public function __construct($size) { $this->size = $size; } public function before() { echo "<dis style='font-size: {$this->size}px'>"; } public function after() { echo "</div>"; } } //实例化输出类 $echo = new EchoText(); //增加装饰器 $echo->addDecorator(new ColorDecorator('red')); //增加装饰器 $echo->addDecorator(new SizeDecorator('40')); //输出 $echo->Index(); ```