} } } /** * 观察者要实现的接口 */ interface Observerable { public function update(); } class Subscriber implements Observerable { public function update() { echo "Callback\n"; } } class Subscriber1 implements Observerable { public function update() { echo "test22222\n"; } } //下面是测试代码 /* 测试 */ $paper = new Paper(); $paper->register(new Subscriber()); $paper->register(new Subscriber1()); //$paper->register(new Subscriber2()); $paper->trigger();