Facade、Proxy、Adapter 和 Decorator 设计模式之间的区别?

发布于 2024-09-14 06:59:06 字数 204 浏览 10 评论 0原文

FacadeProxyAdapterDecorator 设计模式之间有什么区别?

从一般的角度来看,此类模式似乎做同样的事情,即:包装 API 并提供对其的访问

如何区分这些模式?
如何辨别一种模式何时比其他模式更适合?

What is the difference between the Facade, Proxy, Adapter, and Decorator design patterns?

From a generic point of view, such patterns seem to do the same thing, that is: wrap an API and provide access to it.

How to distinguish these patterns?
How to discern when one pattern suits more than the others?

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赠意 2024-09-21 06:59:06

TL;DR

  • 适配器:用于不兼容的接口
  • 外观:用于使接口更简单
  • 代理:用于管理重型和/或复杂的对象
  • >装饰器:用于在运行时扩展它

详细的

适配器使给定的类/对象适应新的接口。对于前者,通常采用多重继承。在后一种情况下,对象由一致的适配器对象包装并传递。

Facade 是通向一组复杂功能的简单门户。您为您的客户制作了一个黑匣子,以减少他们的担忧。

Proxy 提供与代理类相同的接口,并且通常会自己完成一些内务处理工作。因此,您不必制作重对象 X 的多个副本,而是制作轻量级代理 P 的副本,后者依次管理 X 并转换您的调用根据需要。

装饰器用于为您的对象添加更多火药(注意术语“对象”——您通常在运行时动态装饰对象)。您不会隐藏/损害对象的现有接口,但是。

现在您已经涉及到装饰器了,您可能想知道为什么要强调对象这个词——某些语言(如 Java)根本不允许虚拟继承(即 C++ 那样的多重继承)来允许您在编译时完成此操作时间。

由于我们已经引入了多重继承(以及可怕的菱形),因此您需要留意mixins——它们是接口的有序线性链接,以解决多重继承的问题。然而,mixin 的混合效果不太好。我们最终得到了特征——是的,那些无状态的行为小斑点,你总是在C++的模板参数中看到弹出的。特征试图以优雅的方式解决行为的组合和分解问题,而不是多重继承或有序链接。

TL;DR

  • Adapter: for non-compatible interfaces
  • Facade: for making interfaces simpler
  • Proxy: for managing a heavy and/or complex object
  • Decorator: for extending it at runtime

Detailed

Adapter adapts a given class/object to a new interface. In the case of the former, multiple inheritance is typically employed. In the latter case, the object is wrapped by a conforming adapter object and passed around.

Facade is a simple gateway to a complicated set of functionality. You make a black-box for your clients to worry less.

Proxy provides the same interface as the proxied-for class and typically does some housekeeping stuff on its own. So, instead of making multiple copies of a heavy object X you make copies of a lightweight proxy P which in turn manages X and translates your calls as required.

Decorator is used to add more gunpowder to your objects (note the term objects — you typically decorate objects dynamically at runtime). You do not hide/impair the existing interfaces of the object but.

Now that you have decorator involved, you will probably want to know why the emphasis on the word object — some languages (like Java) simply don't allow virtual inheritance (i.e. multiple inheritance as C++ does) to allow you to accomplish this at compile time.

Since we have dragged in multiple inheritances (and the dreaded diamond) you will look out for mixins — which are ordered linear chaining of interfaces to get around the problems of multiple inheritance. However, mixins don't mix that well. And we end up with traits — yes those stateless little blobs of behavior that you see pop-up all the time in template parameters in C++. Traits try to address the issues of composition and decomposition of behavior in an elegant manner while not going either for multiple inheritances or ordered chaining.

夏九 2024-09-21 06:59:06

外观

例如,您可以使用外观来更轻松地调用 API。看一下这个远程外观示例。这里的想法是服务器上代码的完整实现对客户端是隐藏的。客户端调用 1 个 API 方法,该方法又可以在服务器上进行 1 个或多个 API 调用。

适配器

可以在 Wikipedia 的此处找到一个很好的示例。客户端对象 Source 想要调用另一个对象 Target 上的方法,但另一个对象的接口与客户端期望的不同。

输入适配器对象。

它可以从 Source 对象进行调用,并在幕后调用应该使用的 Target 方法。

Source->CallMethodAOnTarget() ---< Adaptor.CallMethodAOnTarget() 这个调用 ---> Target.MethodWithDifferentSignatureAndName(int i)

至于Proxy,我对这种设计模式没有任何经验。

Facade

You could use a facade, for example, to make calls to an API easier. Take a look at this example of a remote facade. The idea here is that the full implementation of the code on the server is hidden away from the client. The client calls 1 API method which, in turn, can make 1 or more API calls on the server.

Adapter

A good example of this can be found here, on Wikipedia. A client object Source would like to call a method on another object Target, but that other object's interface differs to what the client is expecting.

Enter the adapter object.

It can take a call from the Source object and, behind the scenes, call the Target method which should be used.

Source->CallMethodAOnTarget() ---< Adaptor.CallMethodAOnTarget() this calls ---> Target.MethodWithDifferentSignatureAndName(int i)

As for Proxy, I don't have any experience of this design pattern.

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