转自：http://ranseti.top/article/retrofit_github_api_demo
直接上代码

import com.google.gson.Gson;
import java.io.IOException;
import java.util.List;
import retrofit2.Call;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.GET;
import retrofit2.http.Path;


/**
 * Created by qy on 2018/1/29.
 */

public class RetrfitTest {

    public static void main(String[] args) {
        try {
            retrfitTest();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void retrfitTest() throws IOException {
        //创建一个非常简单的指向GitHub API的REST适配器。
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(API_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        //创建我们的GitHub API接口的一个实例。
        GitHub github = retrofit.create(GitHub.class);
        //创建一个调用实例来查找Retrofit贡献者。
        Call<List<Contributor>> call = github.contributors("square", "retrofit");
        //获取并打印库的贡献者列表。
        Response response = call.execute();
        System.out.println(response.code() + "\n"
                + response.toString() + "\n"
                + new Gson().toJson(response.body()));
    }

    public static class Contributor {
        public final String login;
        public final int contributions;

        public Contributor(String login, int contributions) {
            this.login = login;
            this.contributions = contributions;
        }
    }

    //https://api.github.com/repos/square/retrofit/contributors
    public static final String API_URL = "https://api.github.com";
    public interface GitHub {
        @GET("/repos/{owner}/{repo}/contributors")
        Call<List<Contributor>> contributors(
                @Path("owner") String owner,
                @Path("repo") String repo);
    }

}

点击main()方法运行结果为

200
Response{protocol=http/1.1, code=200, message=OK, url=https://api.github.com/repos/square/retrofit/contributors}
[{"login":"JakeWharton","contributions":871},{"login":"swankjesse","contributions":211},{"login":"pforhan","contributions":48},{"login":"eburke","contributions":36},{"login":"dnkoutso","contributions":26},{"login":"edenman","contributions":24},{"login":"loganj","contributions":17},{"login":"NightlyNexus","contributions":14},{"login":"rcdickerson","contributions":14},{"login":"rjrjr","contributions":13},{"login":"kryali","contributions":9},{"login":"adriancole","contributions":8},{"login":"holmes","contributions":7},{"login":"swanson","contributions":7},{"login":"JayNewstrom","contributions":6},{"login":"crazybob","contributions":6},{"login":"Jawnnypoo","contributions":6},{"login":"danrice-square","contributions":5},{"login":"Turbo87","contributions":5},{"login":"ransombriggs","contributions":4},{"login":"vanniktech","contributions":4},{"login":"naturalwarren","contributions":4},{"login":"guptasourabh04","contributions":4},{"login":"artem-zinnatullin","contributions":3},{"login":"codebutler","contributions":3},{"login":"icastell","contributions":3},{"login":"jjNford","contributions":3},{"login":"f2prateek","contributions":3},{"login":"koalahamlet","contributions":3},{"login":"alexgyori","contributions":2}]