PHP设计模式之装饰者模式

<?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/>");