RxJava+Retrofit的瀑布流Demo

前言

学习RxJava+Retrofit的开发框架之余，做了一个小的Demo。主要功能是获取图片数据，以瀑布流形式展示。项目效果：

项目效果.gif

代码实现：

网络请求的对外接口通过HttpManager这个类访问：

public class HttpManager {

    //base http service
    private HttpService httpService;

    //构造方法私有
    private HttpManager() {
        httpService = RetrofitClient.getInstance().getHttpService(HttpService.class);
    }

    /**
     * create singleton instance
     */
    private static class SingletonHolder {
        private static final HttpManager INSTANCE = new HttpManager();
    }

    /**
     * obtain the instance
     *
     * @return
     */
    public static HttpManager getInstance() {
        return SingletonHolder.INSTANCE;
    }

    public void getImages(String query,int startIndex,int endIndex,Subscriber subscriber){
        Observable observable = httpService.getImageData(query,startIndex,endIndex);
        RetrofitClient.getInstance().toSubscribe(observable,subscriber);
    }
}

其中httpService是Retrofit的接口类：

public interface HttpService {

    @GET("j")
    Observable getImageData(@Query("q") String q,@Query("sn") int sn,@Query("pn") int pn);
}

Retrofit以接口的形式定义需要的网络请求。
在HttpManager的构造方法中：

   //构造方法私有
    private HttpManager() {
        httpService = RetrofitClient.getInstance().getHttpService(HttpService.class);
    }

这里我们将自定义的HttpService接口类，与Retrofit进行关联，目的是告诉Retrofit用什么请求方法，什么参数，返回结果长什么样。
RetrofitClient中对Retrofit的一些基本参数做配置：

public class RetrofitClient {

    private Retrofit retrofit;

    private RetrofitClient() {
    }

    /**
     * create singleton instance
     */
    private static class SingletonHolder {
        private static final RetrofitClient INSTANCE = new RetrofitClient();
    }

    /**
     * obtain the instance
     *
     * @return
     */
    public static RetrofitClient getInstance() {
        return SingletonHolder.INSTANCE;
    }

    /**
     * get base http Service
     *
     * @param clazz
     * @param    class which need to init
     * @return return formatted instance of Class of T
     */
    public  T getHttpService(Class clazz) {
        return getHttpService(clazz, HttpConsts.BASE_URL);
    }

    public  T getHttpService(Class clazz, String baseUrl) {
        return getHttpService(clazz, baseUrl, GsonConverterFactory.create());
    }

    public  T getHttpService(Class clazz, String baseUrl, Converter.Factory factory) {
        OkHttpClient.Builder okBuilder = new OkHttpClient.Builder()
                .connectTimeout(HttpConsts.TIMEOUT, TimeUnit.MILLISECONDS);

        Retrofit.Builder builder = new Retrofit.Builder();
        builder.client(okBuilder.build());
        builder.addCallAdapterFactory(RxJavaCallAdapterFactory.create());
        builder.baseUrl(baseUrl);
        if (factory != null) {
            builder.addConverterFactory(factory);
        }
        retrofit = builder.build();

        return retrofit.create(clazz);
    }

    /**
     * config to base subscribe
     *
     * @param observable
     * @param subscriber
     * @param 
     */
    public  void toSubscribe(Observable observable, Subscriber subscriber) {
        observable.subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(subscriber);
    }

}

这里有两个方法。一个是getHttpService方法，在这个方法中加入了GsonConverterFactory进行json转换，加入了RxJavaCallAdapterFactory对RxJava做支持。另一个方法toSubscribe方法是为网络请求的结果处理提供一个回调。
实际的网络请求如下:

 public void getImages(String query,int startIndex,int endIndex,Subscriber subscriber){
        Observable observable = httpService.getImageData(query,startIndex,endIndex);
        RetrofitClient.getInstance().toSubscribe(observable,subscriber);
    }

这里的observable已经是Retrofit网络请求回来的结果。后面通过toSubscribe方法将结果的处理回调给外部调用者。
工程地址：https://github.com/PaulZJ/WaterFallFlow