从第三方库解耦

Question

I am using a third party HTTP client to make GET, POST calls. I don't want to tie my code to this library. So I've decided to create an interface called HttpClient and an implementation of it called HttpClientImpl.

One of the methods in the interface is:

Response get(String url);

The Response object being returned from the interface is the object from the third party library. So this technically does not decouple my code from the third party library.

What is the best approach to decouple myself? Should I create my own response object that can wrap the response of the third party library?

Answer 1

This is a classic case of the Mediator design pattern: The class which uses the HTTP client shouldn't be exposed to neither the HTTP client implementation (which you've already encapsulated) nor its response object.

Using generics here will not prevent the using class from knowing the response class in this case.

As you suggested - have a wrapping response class / have a converter from the 3rd party response to one of your own.

Answer 2

Instead of abstracting the http library, have you considered abstracting the repositories you are accessing through Http? Say for example, you have the restful endpoints for Tweets:

GET    https://someapi.com/Tweets
GET    https://someapi.com/Tweets/{id}
POST   https://someapi.com/Tweets
PUT    https://someapi.com/Tweets/{id}
DELETE https://someapi.com/Tweets/{id}

It would make sense to have a TweetRepository class, which can create, read, update and delete tweets. The interface for this class might look something like the following:

public interface TweetRepository {
    public List<Tweet> get();
    public int add(Tweet tweet);
    public void remove(int id);
    public Tweet get(int id);
    public void update(int id, Tweet tweet);
}

If your controllers use the interface, then you can make your implementation use whatever http library you want without introducing coupling.