PHP设计模式门面模式
PHP设计模式——门面模式
声明:本系列博客参考资料《大话设计模式》,作者程杰。
门面模式(有时候也称外观模式)是指提供一个统一的接口去访问多个子系统的多个不同的接口,它为子系统中的一组接口提供一个统一的高层接口。使用子系统更容易使用。
案例:炒股票,新股民不了解证券知识做股票,是很容易亏钱的,需要学习的知识太多了,这样新手最好把炒股的事情委托给基金公司,基金公司了解证券知识,那么新股民把自己的股票托管给基金公司去运营,这样新股民不必了解哪只股票的走势就可以完成股票的买卖。基金公司在这里就是一个门面,针对于新股民的门面。
UML类图:
角色分析:
门面(FacadeCompany)角色:此角色封装一个高层接口,将客户端的请求代理给适当的子系统对象,是门面模式的核心接口。
子系统(ICBC)角色:实现子系统的具体功能,处理FacadeCompany对象指派的任务。子系统没有FacadeCompany的任何信息,没有对FacadeCompany对象的引用。
具体代码案例:
<!--?php /** * Created by PhpStorm. * User: LYL * Date: 2015/5/16 * Time: 11:07 */ /**阿里股票 * Class Ali */ class Ali { function buy() { echo 买入阿里股票<br/-->; } function sell() { echo 卖出阿里股票 ; } } /**万达股票 * Class Wanda */ class Wanda { function buy() { echo 买入万达股票 ; } function sell() { echo 卖出万达股票 ; } } /**京东股票 * Class Jingdong */ class Jingdong { function buy() { echo 买入京东股票 ; } function sell() { echo 卖出京东股票 ; } } /**门面模式核心角色 * Class FacadeCompany */ class FacadeCompany { private $ali; private $wanda; private $jingdong; function __construct() { $this->ali=new Ali(); $this->jingdong=new Jingdong(); $this->wanda=new Wanda(); } function buy() { $this->wanda->buy(); $this->ali->buy(); } function sell() { $this->jingdong->sell(); } }
客户端调用代码:
header(Content-Type:text/html;charset=utf-8); //------------------------门面模式测试代码------------------ require_once ./Facade/Facade.php; $lurenA=new FacadeCompany(); $lurenA->buy(); $lurenA->sell();
优势:
1)它可以对客户屏蔽子系统组件,因而减少了客户处理的对象的数目并使得子系统使用起来更加方便。
2) 它实现了子系统与客户之间的松耦合关系,而子系统内部的功能组件往往是紧耦合的。松耦合关系使得子系统的组件变化不会影响到它的客户。 Facade模式有助于建立层次结构系统,也有助于对对象之间的依赖关系分层。
3) Facade模式可以消除复杂的循环依赖关系。这一点在客户程序与子系统是分别实现的时候尤为重要。在大型软件系统中降低编译依赖性至关重要。在子系统类改变时,希望尽量减少重编译工作以节省时间。用Facade可以降低编译依赖性,限制重要系统中较小的变化所需的重编译工作。
4)Facade模式同样也有利于简化系统在不同平台之间的移植过程,因为编译一个子系统一般不需要编译所有其他的子系统。

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