接口的要点

发布于 2024-09-28 08:06:10 字数 326 浏览 8 评论 0原文

可能的重复：
我如何知道何时创建接口？

我想知道使用接口的意义。

你使用接口吗？如果是这样，您什么时候决定使用它们，什么时候决定不使用它们？

我目前已经为我的服务层和存储库层定义了接口，但我想知道我是否错过了它们有用的其他地方。

我想我只是不完全理解他们的目的。

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花开半夏魅人心 2024-10-05 08:06:10

接口定义契约。任何实现接口的类都必须履行该契约。这意味着该类必须实现接口中定义的方法。

接口基本上表示“我正在定义所有实现者都必须执行的操作。我不关心您如何执行此操作，但您必须支持我指定的这些操作”。

接口的另一个用途是您可以在方法签名或类型定义中使用它们来指定对象的最通用类型。例如，在 Java 中，Map 是一个由其他类（例如 HashMap 或 LinkedHashMap）实现的接口。 HashMap 和 LinkedHashMap 本质上都是 Map 类型。它们实现相同的方法，但执行不同的操作（LinkedHashMap 保留插入顺序）。

考虑一下您有一个接受地图的方法的情况。如果没有接口，则需要为每种类型的映射指定一个方法。事实上，您可以通过重载方法来做到这一点，但这种方法不是很好。更好的方法是将方法参数的类型指定为Map。然后，任何实现 Map 的类都可以传递给该方法。这样，您不必为每种类型的映射指定方法，而且您也不会将使用您的方法的人限制为映射的特定实现。

接口还保证指定的功能存在于实现类中。因此，它还提供了访问该功能的标准方法。当您设计 API 时，接口也很有用（这样您就可以为要公开的内容指定标准接口）。

接口的另一个好处是它使重构变得容易。假设您想要切换某种对象的实现。该对象可能是方法参数，也可能是类属性。由于您已将该参数或对象键入为接口，因此您可以简单地创建一个实现该接口的新类并传递该类。由于您使用了该接口，因此您没有对类的细节做出额外的假设。该接口抽象出您正在使用的类的实现细节。这样，您最终就不会做出使您的代码与特定实现过于紧密耦合的假设。

总而言之，接口是关于抽象和契约。通过抽象，您可以隐藏底层细节并仅公开您需要公开的最低限度的细节。这样，使用您的类或接口的人就不会受到实现细节的负担。所有这些信息都巧妙地隐藏在实现该接口的特定类中。合同确保全面标准化；使用该接口的人确信实现该接口的所有类都公开相同的方法。

An interfaces defines a contract. Any class that implements an interface has to fulfil that contract. This means that the class must implement methods defined in the interface.

An interface basically says "I'm defining something that all implementers must do. I don't care how you do it, but you must support these operations that I've specified".

Another use of interfaces is that you can use them in method signatures or type definitions to specify the most generic type of an object. For example, in Java Map is an interface that is implemented by other classes like HashMap or LinkedHashMap. Both HashMap and LinkedHashMap are essentially of type Map. They implement the same methods, but they do things differently (LinkedHashMap preserves insertion-order).

Consider the situation where you have a method that accepts maps. If you didn't have interfaces, you would need to specify a method for each type of map. Indeed, you could do that via overloaded methods, but that approach is not very good. The better way is to specify the type of the method argument as Map. Then, any class that implements Map can be passed in to the method. This way, you don't have to specify a method for each type of map, and also you are not restricting the person who uses your method, to specific implementations of the map.

An interface also guarantees that the specified functionality is present in implementing classes. As such, it also provides a standard way to access that functionality. Interfaces are also useful when you are designing an API (that way you can specify a standard interface to the things you want to expose).

Another benefit of interfaces is that it makes refactoring easy. Let's say that you want to switch out an implementation of a some sort of object. The object might be a method argument or it may be a class property. Since you've typed that argument or object as an interface, you can simply create a new class that implements the interface and pass that class instead. Since you used the interface, you didn't make an extra assumptions as to the details of the class. The interface abstracts out the implementation details of the class that you're using. That way you don't end up making assumptions that makes your code too tightly-coupled to a specific implementation.

To sum it up, interfaces are about abstraction and contracts. With abstraction you hide the underlying details and expose only the bare minimum that you need to expose. That way the person who uses your class or interface is not burdened with the implementation details. All that information is neatly hidden inside the specific class that implements the interface. The contract ensures standardization across the board; a person who uses the interface is sure that all classes that implement the interface expose the same methods.

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微暖i 2024-10-05 08:06:10

接口是用来告诉其他人一个类做某事的。

例如，如果您有一个实现 IInjurable 的 SoccerPlayer 类 - 您从该类代码的第一行就知道，SoccerPlayer 实例知道要做什么受伤时要做的事情（你可能知道连字符之后）。

现在考虑一下实现 IEnumerable 、 IQueryable 或 IDisposable 告诉您有关对象的信息，而无需了解有关实现本身的任何信息..
好像很多..

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抱着落日 2024-10-05 08:06:10

界面就像一个规则列表。您指定一个类的要求，并且对于任何实现此接口的类，您知道它们将遵循这些规则。您可以将这些类强制转换为此接口类型，并对它们进行操作，因为您知道它们具有您认为需要的方法、属性和事件。

ASP.Net 中的一些重要接口包括：

ICallbackEventHandler
IDisposable

最近，当我想确保用于特定目的的所有类都具有特定的方法和事件时，我创建了自己的接口。知道了这一点，我可以首先通过强制转换并验证来检查它是否实现了接口：

IMyInterface myinterface = myclass as IMyInterface;
if (myinterface == null)
{
    //did NOT implement the interface
}
else
{
    //did implement the interface
    //call the method we KNOW is there.
    myinterface.MyMethod(myparemeter);
}

An interface is like a list of rules. You designate the requirements of a class, and for any class that implements this interface, you know that they will follow these rules. You can cast those classes as this interface type, and operate on them knowing that they have the methods, properties, and events that you decided are required.

Some important interfaces in ASP.Net are:

ICallbackEventHandler
IDisposable

I created my own interface recently when I wanted to be sure all of the classes that were used for a specific purpose have a specific method and event. Knowing that, I could first check that it implements the interface by casting it and verifying:

IMyInterface myinterface = myclass as IMyInterface;
if (myinterface == null)
{
    //did NOT implement the interface
}
else
{
    //did implement the interface
    //call the method we KNOW is there.
    myinterface.MyMethod(myparemeter);
}

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