准备

    compile 'com.squareup.retrofit2:retrofit:2.0.0-beta3'
    compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta3' //已经包含了gson
    compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta4'
    compile 'io.reactivex:rxjava:1.1.0'
    compile 'io.reactivex:rxandroid:1.1.0'
    compile 'com.squareup.okio:okio:1.6.0'
    compile 'com.squareup.okhttp3:okhttp:3.2.0'
    compile 'com.squareup.okhttp3:logging-interceptor:3.2.0' // 看log需要

关键代码

1.定义api接口

public interface CodeHubService {

    @GET("/v2/showcases")
    Observable<ArrayList<ShowCase>> getShowCaseList();
}

2.创建Retrofit

private Retrofit mRetrofit;
HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
            @Override
            public void log(String message) {
                Log.d("CodeHubServiceManager", message);
            }
        });
//        自定义gson解析(List不需要也能自己解析)
//        Type showCaseType = new TypeToken<ArrayList<ShowCase>>(){}.getType();
//        Gson gson = new GsonBuilder().registerTypeAdapter(showCaseType,
//                new JsonDeserializer<ArrayList<ShowCase>>() {
//                    @Override
//                    public ArrayList<ShowCase> deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
//                        return new Gson().fromJson(json, typeOfT);
//                    }
//                }).create();

loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .addInterceptor(loggingInterceptor) // 拦截器
                .connectTimeout(20, TimeUnit.SECONDS)
                .build();

mRetrofit = new Retrofit.Builder()
                .baseUrl("http://trending.codehub-app.com")
                .client(okHttpClient)  // okHttpClient实例,不调用使用默认
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();

3. 调用api接口,获取Observable,并进行相关设置,调用subscribe

private CodeHubService mCodeHubService;

mCodeHubService = mRetrofit.create(CodeHubService.class);

Observable<ArrayList<ShowCase>> showCaseObservable = codeHubService.getShowCaseList()
                    .subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .unsubscribeOn(Schedulers.io()); // 此处注意,***On每个调用返回的都是新的Observable

showCaseObservable .subscribe(new Subscriber<ArrayList<ShowCase>>() {
                    @Override
                    public void onCompleted() {
                        Toast.makeText(getContext(), "onCompleted", Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onError(Throwable e) {
                        Toast.makeText(getContext(), "onError " + e.getMessage(), Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onNext(ArrayList<ShowCase> showCases) {
                        Toast.makeText(getContext(), "showCases size=" + showCases.size(), Toast.LENGTH_SHORT).show();
                        showCaseAdapter.updateData(showCases);
                    }
                });

填坑

1. Observable的subscribeOn,observeOn,unsubscribeOn是返回新的对象,而不是修改

参考

http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0106/2275.html (Okhttp基本使用)
http://jakewharton.github.io/butterknife/
http://square.github.io/retrofit/