<?php

abstract class Subject { // 抽象主题角色

    abstract public function action();

}

class RealSubject extends Subject { // 真实主题角色

    public function __construct() {}

    public function action() {}

}

class 大专栏  设计模式详解及PHP实现：代理模式lass="nc">ProxySubject extends Subject { // 代理主题角色

    private $_real_subject = NULL;

    public function __construct() {}

    public function action() {

        $this->_beforeAction();

        if (is_null($this->_real_subject)) {

            $this->_real_subject = new RealSubject();

        }

        $this->_real_subject->action();

        $this->_afterAction();

    }

    private function _beforeAction() {}

    private function _afterAction() {}

}

// client

$subject = new ProxySubject();

$subject->action();

?>