关于后端:结构型设计模式代理-Proxy

代理与装璜器很像，都是在原有类根底上，增量做改变。

不同在于，代理模式下，client 间接操作的就是 proxy 对象，new 的就是 proxy 对象，不能够让 client 间接操作被代理对象，相当于原始类被齐全暗藏掉了。

类比现实生活，租房代理是不会让客户间接跟房东分割的，客户签合同也是跟代理签，全程没有跟房东交互。

根底性能接口 Subject

定义根本动作
被代理类

实现 Subject 接口，实现业务逻辑
Proxy 代理类

实现 Subject 接口

图中 ServiceInterface 是根底接口，定义一个 operation 办法。Service 是被代理类，实现了 ServiceInterface 接口，Proxy 是代理类，也实现了 ServiceInterface 接口。

Proxy 类的 operation 办法做了 CheckAccess 操作，容许的话再调用被代理类的 operation 办法。

interface Subject
{public function request(): void;
}

class RealSubject implements Subject
{public function request(): void
    {echo "RealSubject: Handling request.\n";}
}

class Proxy implements Subject
{
    private $realSubject;

    public function __construct(RealSubject $realSubject)
    {$this->realSubject = $realSubject;}

    public function request(): void
    {if ($this->checkAccess()) {$this->realSubject->request();
            $this->logAccess();}
    }

    private function checkAccess(): bool
    {
        echo "Proxy: Checking access prior to firing a real request.\n";

        return true;
    }

    private function logAccess(): void
    {echo "Proxy: Logging the time of request.\n";}
}

function clientCode(Subject $subject)
{$subject->request();
}

echo "Client: Executing the client code with a real subject:\n";
$realSubject = new RealSubject();
clientCode($realSubject);

echo "\n";

echo "Client: Executing the same client code with a proxy:\n";
$proxy = new Proxy($realSubject);
clientCode($proxy);

output:

Client: Executing the client code with a real subject:
RealSubject: Handling request.

Client: Executing the same client code with a proxy:
Proxy: Checking access prior to firing a real request.
RealSubject: Handling request.
Proxy: Logging the time of request.

本文由 mdnice 多平台公布

关于后端:结构型设计模式代理-Proxy

简介

角色

类图

代码