使用Volley的android中的MVVM架构 [英] MVVM architecture in android Using Volley

问题描述

我正在研究MVVM，看它是否可以为我的后续项目提供帮助.到目前为止，我所了解的是，我需要使用 ViewModel 用于保存我的UI数据.我还需要使用一个Repository类来执行所有对WebServices的请求，并且我正在使用Volley库.

I'm studying the MVVM to see if it can help me for my upcoming projects. What I understand so far, is that I need to use a ViewModel for holding my UI datas. I also need to use a Repository class to perform all my Requests to WebServices, and I'm using the Volley Library.

这就是我所做的:

ViewModel

public class MyViewModel extends ViewModel {

    private MyRepository repository;
    private MutableLiveData<MyPojo> pojo;

    public MyViewModel(MyRepository repository) {
        this.repository = repository;
        this.pojo = new MutableLiveData<>();
    }

    public LiveData<MyPojo> updatePojo(){
        pojo.postValue(repository.getPojo());
        return pojo;
    }
}

存储库类

public class MyRepository {

private Application application;
private LiveData<MyPojo> pojo;

public MyRepository(Application application) {
    this.application = application;
}

public MyPojo getPojo(){
    if(pojo == null){
        ApiRequest apiRequest = new ApiRequest(ApiSingleton.getInstance(application).getRequestQueue(), application);
        apiRequest.apiGetRequest(ApiRequest.MY_ENDPOINT, null, new ApiRequest.apiCallback() {
            @Override
            public void onSuccess(Context context, JSONObject jsonObject) {
                pojo = ApiResponseParser.parse(jsonObject, MyPojo.class);
            }

            @Override
            public void onError(Context context, String message) {

            }
        });
    }
    return pojo;
}

}

在此处指定了

It's specified here that a ViewModel must never reference a view, Lifecycle, or any class that may hold a reference to the activity context. As you can see, I must use a context in order to perform a Volley request in my Repository class, and my ViewModel has a reference on this class.

我在设计中缺少什么吗?排球在这里不兼容吗?

Am I missing something in my design? Is Volley not compatible here?

推荐答案

而不是将 Application 传递到MyRepository的 constructor 并创建 ApiRequest ，您可以将 ApiRequest 传递给MyRepository的 constructor .

Instead of passing the Application to your MyRepository's constructor and creating ApiRequest, you can pass the ApiRequest to MyRepository's constructor.

public MyRepository(ApiRequest apiRequest) {
    this.apiRequest = apiRequest;
}

现在 MyRepository 没有对 Context 的引用.

而且，关于直接引用 MyRepository 的 ViewModel ，您可以依赖反转:

And, regarding ViewModel having direct reference to MyRepository, you can do dependency inversion:

使用方法 getPojo()创建一个接口，例如 MyDataStore . MyRepository 将实现此接口.创建 MyViewModel 时，您会将 MyRepository 传递给它，但是 MyViewModel 将仅引用 MyDataStore ./p>

Create an interface, for instance, MyDataStore with the method getPojo(). MyRepository will implement this interface. While creating MyViewModel, you will pass the MyRepository to it, but MyViewModel will only have reference to MyDataStore.

interface MyDataStore {
   ... getPojo()
}

public class MyRepository implements MyDataStore {
   ...
}

public MyViewModel(MyDataStore dataStore) {
        this.dataStore = dataStore;
        this.pojo = new MutableLiveData<>();
}

这篇关于使用Volley的android中的MVVM架构的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！