Retrofit封装

Retrofit结合Rxjava封装思路：

• 主要分为四个部分：实体类 ，Observable ，Subscriber，Retrofit。

实体类

一般客户端都是通过链接从服务端获取数据，然后再注入到应用中，从而更新UI。返回的数据一般为JSON。

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

常见结构就是如此，对于我们个人而言呢有用的仅仅是tems部分，而且后期需求变化的话，items里的json数据结构会发生改变的，对应的类结构会发生改变，所以用泛型来解决items类多变的问题。把items中用到的类单独封装。

public class StackUserEntity {

    /**
     * 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>>

Retrofit

此类更多封装的时关于Retrofit的配置及请求过程，并不涉及服务接口。以单例模式封装。

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;


    //构造函数私有化
    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();
    }

    //懒汉式单例，并加入线程锁，使得线程安全(不会因为多线程调用时创造出两个实例)    
    public static  HttpMethodes getInstance() {
        if (httpMethodes == null) {
            synchronized (HttpMethodes.class) {
                if (httpMethodes == null) {
                    httpMethodes = new HttpMethodes();
                }
            }
        }
        return httpMethodes;
    }


    //这里是把线程的调度封装了，避免重复写。
    public  void getMovie(Subscriber subscriber,Observable observable) {
        toSubscriber(observable,subscriber);
    }


    //因为是单例，服务接口的对象创建和url的参数是不能写死的。这里也用泛型。
    public  T toService(final Class 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这部分更多的是封装Retrofit的服务接口参数传递即事件的处理。因这部分为变化的不可能在Retrofit单例那里封装。

private Observable> getSource() {
   return methodes.toService(StackExchangeService.class)
                  .getSource(10) //此处使用map操作符呢是为了提取StackUserEntity实体类部分的List；
                   .map(new Func1>, List>() {
                        @Override
                        public List call(StackUserEntity> listStackUserEntity) {
                              return listStackUserEntity.getItems();
                           }
                     });
}

Subscriber

创建一个继承Subscriber的抽象类，把OnNext( )定义为抽象方法，因为OnNext()方法中，更多的传递数据给UI使用。

public abstract class ProgressSubscriber extends Subscriber {

    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, "当前任务已经完成", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onError(Throwable e) {
        destroyProgress();
        Toast.makeText(context, "当前任务出现了错误，请稍候重试", Toast.LENGTH_SHORT).show();
    }


//可以根据需求写入正确的类型
    @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("正在加载中，请稍候！");

            dialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
                @Override
                public void onCancel(DialogInterface dialog) {
                    if (! isUnsubscribed()) {
                        unsubscribe();  //当加载框，加载完成时取消对Observable的订阅(即关闭url连接。)
                    }
                }
            });
        }

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