java如何在socket回调中使用观察器？

Question

我是一名安卓开发者，对测试新技术感兴趣。 知道吗，我想使用架构组件来改进我的项目

我想列出服务器上的文章，并在recyclerView中显示它们。 应该注意的是，我使用WebSocket与服务器通信

我的日常工作如下：

首先，我从viewModel类调用了loadArticles方法：

BlogViewModel = ViewModelProvders.of(this).get(BlogViewModel.class);
viewModel.loadArticles();

BlogViewModel主体下方：

public class BlogViewModel extends ViewModel {

private BlogRepository repository;
private CompositeDisposable compositeDisposable = new CompositeDisposable();

public ObservableField<Boolean> isLoading = new ObservableField<>();
public MutableLiveData<List<Article>> articles = new MutableLiveData<>();


public BlogViewModel() {
    this.repository = new BlogRepository();
}

public void loadArticles() {
    isLoading.set(true);

    compositeDisposable.add(repository
            .getArticles()
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeWith(new DisposableObserver<List<Article>>() {
                @Override
                public void onNext(List<Article> data) {
                    articles.setValue(data);
                }

                @Override
                public void onError(Throwable e) {
                    // FIXME: 3/31/2019
                }

                @Override
                public void onComplete() {
                    isLoading.set(false);
                }
            }));
}

@Override
protected void onCleared() {
    super.onCleared();

    if (!compositeDisposable.isDisposed()) {
        compositeDisposable.dispose();
    }
  }
}

此外，BlogRepository类的定义如下：

public class BlogRepository {

private BlogRemoteDataSource remoteDataSource = BlogRemoteDataSource.getInstance();

public Observable<List<Article>> getArticles() {
    if (Util.isConnect()) {
        return remoteDataSource.getArticles();
    } else {
        return null;
    }
  }
}

BlogRemoteDataSource类的定义如下：

public class BlogRemoteDataSource {

private Application app = (Application) Application.getInstance();
private List<Article> articles;

public static BlogRemoteDataSource getInstance() {
    return new BlogRemoteDataSource();
}

public Observable<List<Article>> getArticles() {
    JSONObject objData = new JSONObject();
    try {
        objData.put("itemID", "");
    } catch (JSONException e) {
        e.printStackTrace();
    }

    app.getSocket().observe(app.getOwner(), socket -> socket.event(Api.EVENT_GET_ARTICLE)
            .data(objData)
            .setCallbacks(new SocketCallback() {
                @Override
                public void onSuccess(JSONObject data) {
                    try {
                        articles = Article.parse(data.getJSONArray(Constant.PARAM_BODY));
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void onError(int code, String message) {
                }
            }).send());

    return Observable.just(articles);
    }
}

我的问题是当我返回可观察的。只是（文章）作为输出。执行这一行后，类中的onNext方法会被触发一次BlogViewModel，但当从服务器获取文章列表和值时，不会触发onNext方法

请指导我如何告诉ViewModel，数据准备好了吗

提前谢谢

Answer 1

您好，您可以使用observeForever而不是observeonly，因为observeForever（）不与任何LifecycleOwner绑定。因此，请按如下方式使用：

First remove your BlogRepository class and update BlogViewModel as below:

public class BlogViewModel extends ViewModel {

private CompositeDisposable compositeDisposable = new CompositeDisposable();
private BlogRemoteDataSource remoteDataSource = BlogRemoteDataSource.getInstance();
public ObservableField<Boolean> isLoading = new ObservableField<>();

public BlogViewModel() {
    this.repository = new BlogRepository();
}

public void loadArticles() {
    isLoading.set(true);
    remoteDataSource.getArticles();
}

@Override
protected void onCleared() {
    super.onCleared();
    if (!compositeDisposable.isDisposed()) {
        compositeDisposable.dispose();
    }
  }
}

然后更新BlogRemoteDataSource，如下所示：

public class BlogRemoteDataSource {

private Application app = (Application) Application.getInstance();
public MutableLiveData<List<Article>> articles = new MutableLiveData<>();

public static BlogRemoteDataSource getInstance() {
    return new BlogRemoteDataSource();
}

public void getArticles() {
    JSONObject objData = new JSONObject();
    try {
        objData.put("itemID", "");
    } catch (JSONException e) {
        e.printStackTrace();
    }

    app.getSocket().observeForever(app.getOwner(), socket -> socket.event(Api.EVENT_GET_ARTICLE)
            .data(objData)
            .setCallbacks(new SocketCallback() {
                @Override
                public void onSuccess(JSONObject data) {
                    try {
                        List<Article> newArticeList = Article.parse(data.getJSONArray(Constant.PARAM_BODY));
                        articles.postValue(newArticeList);
                        articles.notifyObserver();
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void onError(int code, String message) {
                }
            }).send());
    }
}

希望现在有帮助！！：）