<?php

/*

装饰者模式动态地将责任附加到对象上。若要扩展功能，装饰者提供了比继承更有弹性的替代方案。

*/

header("Content-type:text/html; charset=utf-8");

//使用继承进行组合

abstract class MessageBoardHandler

{

    public function __construct(){}

    abstract public function filter($msg);

}

class MessageBoard extends MessageBoardHandler

{

    public function filter($msg)

    {

        return "处理留言板上的内容".$msg;

    }

}

$obj = new MessageBoard();

echo $obj -> filter("一定要学好装饰模式<br/>");

// --- 以下是使用装饰模式 ----

// 定义装饰者类----

// 引入被装饰殾对象---

class MessageBoardDecorator extends MessageBoardHandler

{

    private $_handler = null;

    public function __construct($handler)

    {

        parent::__construct();

        $this -> _handler = $handler;

    }

    public function filter($msg)

    {

        return $this -> _handler -> filter($msg);

    }

}

//----

class HtmlFilter extends MessageBoardDecorator

{

    public function __construct($handler)

    {

        parent::__construct($handler);

    }

    public function filter($msg)

    {

        return "过滤掉HTML标签|".parent::filter($msg);

    }

}

class SensitiveFilter extends MessageBoardDecorator

{

    public function __construct($handler)

    {

        parent::__construct($handler);

    }

    public function filter($msg)

    {

        return "过滤掉HTML|".parent::filter($msg);// 过滤掉敏感词的处理这时只是加个文字没有进行处理

    }

}

    $obj = new HtmlFilter(new SensitiveFilter(new MessageBoard()));

    echo $obj->filter("一定学好装饰模式<br/>");