Retrofit結合Rxjava封裝思路：

• 主要分為四個部分：實體類 ，Observable ，Subscriber，Retrofit。

實體類

一般客戶端都是通過鏈接從服務端獲取數據，然后再注入到應用中，從而更新UI。返回的數據一般為JSON。

{
    items: [],
    has_more: true,
    quota_max: 300,
    quota_remaining: 299
}

常見結構就是如此，對于我們個人而言呢有用的僅僅是tems部分，而且后期需求變化的話，items里的json數據結構會發生改變的，對應的類結構會發生改變，所以用泛型來解決items類多變的問題。把items中用到的類單獨封裝。

public class StackUserEntity<T> {

    /**
     * items : [{"reputation":904115,"creation_date":1222430705,"user_type":"registered","user_id":22656,"accept_rate":86,"location":"Reading, United Kingdom","website_url":"http://csharpindepth.com","link":"http://stackoverflow.com/users/22656/jon-skeet","profile_image":"https://www.gravatar.com/avatar/6d8ebb117e8d83d74ea95fbdd0f87e13?s=128&d=identicon&r=PG","display_name":"Jon Skeet"}]
     * has_more : true
     * quota_max : 300
     * quota_remaining : 299
     */

    private boolean has_more;
    private int quota_max;
    private int quota_remaining;
    private T items;   
}

Observable<StackUserEntity<List<ItemsBean>>>

Retrofit

此類更多封裝的時關于Retrofit的配置及請求過程，并不涉及服務接口。以單例模式封裝。

public class HttpMethodes{

    public static final String baseUrl = "https://api.douban.com/v2/movie/";

    private static final int DEFAULT_TIMEOUT = 5;

    private Retrofit retrofit;

    private static HttpMethodes httpMethodes;


    //構造函數私有化
    private HttpMethodes() {
        OkHttpClient.Builder builder =new OkHttpClient.Builder();

        builder.connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS);


        retrofit = new Retrofit.Builder()
                               .baseUrl(baseUrl)
                               .client(builder.build())
                               .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                               .addConverterFactory(GsonConverterFactory.create())
                               .build();
    }

    //懶漢式單例，并加入線程鎖，使得線程安全(不會因為多線程調用時創造出兩個實例)    
    public static  HttpMethodes getInstance() {
        if (httpMethodes == null) {
            synchronized (HttpMethodes.class) {
                if (httpMethodes == null) {
                    httpMethodes = new HttpMethodes();
                }
            }
        }
        return httpMethodes;
    }


    //這里是把線程的調度封裝了，避免重復寫。
    public <T> void getMovie(Subscriber<T> subscriber,Observable<T> observable) {
        toSubscriber(observable,subscriber);
    }


    //因為是單例，服務接口的對象創建和url的參數是不能寫死的。這里也用泛型。
    public <T> T toService(final Class<T> from) {
        return retrofit.create(from);
    }


    private void toSubscriber(Observable o , Subscriber s) {
        o.subscribeOn(Schedulers.io())
                .unsubscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(s);
    }
}

Observable

Observable這部分更多的是封裝Retrofit的服務接口參數傳遞即事件的處理。因這部分為變化的不可能在Retrofit單例那里封裝。

private Observable<List<ItemsBean>> getSource() {
   return methodes.toService(StackExchangeService.class)
                  .getSource(10) //此處使用map操作符呢是為了提取StackUserEntity實體類部分的List<ItemsBean>；
                   .map(new Func1<StackUserEntity<List<ItemsBean>>, List<ItemsBean>>() {
                        @Override
                        public List<ItemsBean> call(StackUserEntity<List<ItemsBean>> listStackUserEntity) {
                              return listStackUserEntity.getItems();
                           }
                     });
}

Subscriber

創建一個繼承Subscriber的抽象類，把OnNext( )定義為抽象方法，因為OnNext()方法中，更多的傳遞數據給UI使用。

public abstract class ProgressSubscriber<T> extends Subscriber<T> {

    private SubscriberOnNextListener mSubscriber;

    @Inject
    public Context context;

    private ProgressDialog dialog; 

    public void setmSubscriber(SubscriberOnNextListener mSubscriber) {
        this.mSubscriber = mSubscriber;
    }

    public void setContext(Context context) {
        this.context = context;
    }

    @Override
    public void onStart() {
        showProgressDialog();
        super.onStart();
    }

    @Override
    public void onCompleted() {
        destroyProgress();
        Toast.makeText(context, "當前任務已經完成", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onError(Throwable e) {
        destroyProgress();
        Toast.makeText(context, "當前任務出現了錯誤，請稍候重試", Toast.LENGTH_SHORT).show();
    }


//可以根據需求寫入正確的類型
    @Override
    abstract public void onNext(T t);

    private void destroyProgress() {

        if (dialog!=null) {
            dialog.dismiss();
        }
        dialog = null;
    }


    private void showProgressDialog() {
        if (dialog == null) {
            dialog = new ProgressDialog(context);
            dialog.setCancelable(true);
            dialog.setMessage("正在加載中，請稍候！");

            dialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
                @Override
                public void onCancel(DialogInterface dialog) {
                    if (! isUnsubscribed()) {
                        unsubscribe();  //當加載框，加載完成時取消對Observable的訂閱(即關閉url連接。)
                    }
                }
            });
        }

        if (! dialog.isShowing()) {
            dialog.show();
        }
    }
}