网络请求--Retrofit2使用方法

Retrofit是Square开发的网络请求库, 简化了网络请求的使用, 这个库太知名了, 好处我就不多说了. 让我们看看如何使用吧?

注意: Retrofit2的beta3版本, 使用Okhttp3, Interceptor使用方式发生改变.

主要
(1) Retrofit2(beta3)的请求方式.
(2) Okhttp3的Interceptor.
(3) Okhttp3的Deserializer.
(4) Retrofit2使用Gson转换器(Converter)和RxJava适配器(Adapter).

Github下载地址

1. 基本请求

使用接口, 区分Get和Post方法.

/*** 网络请求* <p>* Created by wangchenlong on 16/1/21.*/
public interface MarvelService {String END_POINT = "http://gateway.marvel.com/";String PARAM_API_KEY = "apikey";String PARAM_HASH = "hash";String PARAM_TIMESTAMP = "ts";@GET("/v1/public/characters")Observable<List<AvengersCharacter>> getCharacters(@Query("offset") int offset);
}

使用Retrofit类创建接口服务, 指定Gson为转换器, RxJava为适配器.

public class RestDataSource implements Repository {private final MarvelService mMarvelService;@Injectpublic RestDataSource() {// Log信息HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);// 公私密匙MarvelSigningInterceptor signingInterceptor = new MarvelSigningInterceptor(BuildConfig.MARVEL_PUBLIC_KEY, BuildConfig.MARVEL_PRIVATE_KEY);// OkHttp3.0的使用方式OkHttpClient client = new OkHttpClient.Builder().addInterceptor(signingInterceptor).addInterceptor(loggingInterceptor).build();// 选择人物信息Gson customGsonInstance = new GsonBuilder().registerTypeAdapter(new TypeToken<List<AvengersCharacter>>() {}.getType(),new MarvelResultsDeserializer<AvengersCharacter>()).create();// 适配器Retrofit marvelApiAdapter = new Retrofit.Builder().baseUrl(MarvelService.END_POINT).addConverterFactory(GsonConverterFactory.create(customGsonInstance)).addCallAdapterFactory(RxJavaCallAdapterFactory.create()).client(client).build();// 服务mMarvelService = marvelApiAdapter.create(MarvelService.class);}// 返回人物信息@Overridepublic Observable<List<AvengersCharacter>> getCharacters(int currentOffset) {return mMarvelService.getCharacters(currentOffset);}
}

2. Interceptor

Interceptor是拦截器, 在发送之前, 添加一些参数, 或者获取一些信息.
如MarvelSigningInterceptor是添加参数, loggingInterceptor是打印参数.

/*** 添加Key和密码* <p>* Created by wangchenlong on 16/1/21.*/
public class MarvelSigningInterceptor implements Interceptor {private final String mApiKey;private final String mApiSecret;public MarvelSigningInterceptor(String apiKey, String apiSecret) {mApiKey = apiKey;mApiSecret = apiSecret;}@Override public Response intercept(Interceptor.Chain chain) throws IOException {String marvelHash = MarvelApiUtils.generateMarvelHash(mApiKey, mApiSecret);Request oldRequest = chain.request();// 添加新的参数HttpUrl.Builder authorizedUrlBuilder = oldRequest.url().newBuilder().scheme(oldRequest.url().scheme()).host(oldRequest.url().host()).addQueryParameter(MarvelService.PARAM_API_KEY, mApiKey).addQueryParameter(MarvelService.PARAM_TIMESTAMP, MarvelApiUtils.getUnixTimeStamp()).addQueryParameter(MarvelService.PARAM_HASH, marvelHash);// 新的请求Request newRequest = oldRequest.newBuilder().method(oldRequest.method(), oldRequest.body()).url(authorizedUrlBuilder.build()).build();return chain.proceed(newRequest);}
}

addQueryParameter添加网络参数.

Okhttp3使用了装饰者模式, 使用Builder添加Interceptor.

        // OkHttp3.0的使用方式OkHttpClient client = new OkHttpClient.Builder().addInterceptor(signingInterceptor).addInterceptor(loggingInterceptor).build();

3. Deserializer

Deserializer是反序列化, Gson使用, 去除不使用的参数.

public class MarvelResultsDeserializer<T> implements JsonDeserializer<List<T>> {@Overridepublic List<T> deserialize(JsonElement je, Type typeOfT,JsonDeserializationContext context) throws JsonParseException {// 转换Json的数据, 获取内部有用的信息JsonElement results = je.getAsJsonObject().get("data").getAsJsonObject().get("results");return new Gson().fromJson(results, typeOfT);}
}

Gson使用Deserializer, 过滤不用的参数.

        // 选择人物信息Gson customGsonInstance = new GsonBuilder().registerTypeAdapter(new TypeToken<List<AvengersCharacter>>() {}.getType(),new MarvelResultsDeserializer<AvengersCharacter>()).create();

4. 获取数据

Rx选择执行线程和返回线程.

    private void loadData() {mCharactersSubscription = mRepository.getCharacters(0).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(avengersCharacters -> {mMainView.setListData(avengersCharacters);});}

Rxjava+Dagger+Retrofit, 三个编程库, 都已经写完了, 基本都是在一起使用. 文章里面都含有独立Demo, 大家可以配合使用, 感谢Square给我们带来, 的优雅代码.

OK, that’s all! Enjoy it.