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接口如何促进代码的可重用性？

发布于 2025-01-05 05:54:54 字数 29 浏览 0 评论 0原文

一个简单的面试问题。接口如何帮助代码重用？

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靖瑶 2025-01-12 05:54:54

接口允许您将实现与调用类关心的信息分开。这使您能够将您的类与其所依赖的类的深入知识分离。

给定以下接口：

public interface IRepository<T> {
   void Save(T entity);
   void Update(T entity);
   void Delete(T entity);
}

可以针对所述接口对依赖类进行编程，并“屏蔽”细节。

public class SomeService {
    private IRepository<Contact> _contactRepo;

    public SomeService(IRepository<Contact> contactRepo){
        _contactRepo = contactRepo;
    }
}

利用此模式使您能够创建所述接口的不同实现：

public class LinqToSqlRepository<Contact> : IRepository<Contact>
{ /* ... */ }
public class EntityFrameworkRepository<Contact> : IRepository<Contact>
{ /* ... */ }
public class NHibernateRepository<Contact> : IRepository<Contact>
{ /* ... */ }

interfaces allows you to separate the implementation from the information the calling class cares about. This enables you to de-couple your classes from having intimate knowledge of classes it depends on.

Given the following interface:

public interface IRepository<T> {
   void Save(T entity);
   void Update(T entity);
   void Delete(T entity);
}

A dependent class can be programmed against said interface and be "shielded" from the details.

public class SomeService {
    private IRepository<Contact> _contactRepo;

    public SomeService(IRepository<Contact> contactRepo){
        _contactRepo = contactRepo;
    }
}

Utilizing this pattern enables you to create different implementations of said interface:

public class LinqToSqlRepository<Contact> : IRepository<Contact>
{ /* ... */ }
public class EntityFrameworkRepository<Contact> : IRepository<Contact>
{ /* ... */ }
public class NHibernateRepository<Contact> : IRepository<Contact>
{ /* ... */ }

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叶落知秋 2025-01-12 05:54:54

接口将使用者与类的实现细节解耦。这有助于实现可重用性，因为实现接口的类可以更改，而无需更改使用实现的代码。

这很令人困惑，也许一个例子有帮助

public interface IUserAuthentication
{
   public bool Authenticate(string name, string password);
}

现在我将编写消费者，它不关心如何执行身份验证，它只是知道它可以对用户进行身份验证。

public class Consumer
{
  private IUserAutentication _auth;
  public Consumer(IUserAuthentication auth) 
  {
   _auth = auth; 
  }

  public void Working(string username, string password) 
  {
    if (!_auth.Authenticate(username, password)) 
    {
       throw new Exception("error!");
    }
  }
}

无论 IUserAuthentication 服务的实现如何，上面的代码都将起作用。这是重用代码的一种方法。

现在我可以实现 IUserAuthentication 接口

public class AuthenticateJasons : IUserAuthentication
{
  public bool Authenticate(string username, string password) 
  {
    return username == "Jason";
  }
}

public class AuthenticateNoone: IUserAuthentication
{
  public bool Authenticate(string username, string password) 
  {
    return false;
  }
}

重点是这些实现对于消费者来说是无关紧要的。另外，这个问题与 ASP.NET Web 框架无关。这确实是一个与语言/平台/框架无关的问题。无论您选择使用哪种语言来实现，答案都是相同的。

An interface decouples the consumer from the implementation details of a class. This helps enables reusability because the class implementing an interface can change, without needing to change the code consuming the implementation.

That's very confusing, maybe an example helps

public interface IUserAuthentication
{
   public bool Authenticate(string name, string password);
}

Now I will write the consumer, it doesn't care how authentication is performed, it simply knows that it can authenticate users.

public class Consumer
{
  private IUserAutentication _auth;
  public Consumer(IUserAuthentication auth) 
  {
   _auth = auth; 
  }

  public void Working(string username, string password) 
  {
    if (!_auth.Authenticate(username, password)) 
    {
       throw new Exception("error!");
    }
  }
}

The code above will work regardless of the implementation of the IUserAuthentication service. This is one way to reuse code.

Now I can implement the IUserAuthentication interface

public class AuthenticateJasons : IUserAuthentication
{
  public bool Authenticate(string username, string password) 
  {
    return username == "Jason";
  }
}

public class AuthenticateNoone: IUserAuthentication
{
  public bool Authenticate(string username, string password) 
  {
    return false;
  }
}

The point is that these implementations are irrelevant as far as the consumer is concerned. Also, this question is not related to ASP.NET the web framework. This is really a language/platform/framework agnostic question. The answer is the same regardless of the language you choose to implement with.

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