Android - 带有 LiveData 组件的 MVVM 和存储库中的 Retrofit 调用

Question

我想使用以下组件进行身份验证视图(登录(：

• MVVM
• 实时数据
• 改造
• 存储 库

我不知道如何在存储库类中接收到当前视图模型的异步改造调用。

View ->ViewModel -> Repository with LiveData。

有人会有一个想法或一个例子来证明这一点吗？

Answer 1

你可以这样做：

YourActivity.kt

class YourActivity : AppCompatActivity() {
private val myViewModel by lazy {
return@lazy ViewModelProviders.of(this).get(MyViewModel::class.java) }
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onViewReady(savedInstanceState)
myViewModel.callApi() // You can do it anywhere, on button click etc..
observeResponseData() // observe it once in onCreate(), it'll respect your activity lifecycle
}
private fun observeResponseData() {
myViewModel.liveData.observe(this, Observer { data ->
// here will be your response
})
}
}

MyViewModel.kt

class MyViewModel : ViewModel() {
val liveData = MutableLiveData<Your response type here>()
val myRepository = MyRepository()
fun callApi() {
myRepository.callMyRetrofitApi(liveData)
}
}

MyRepository.kt

class MyRepository {
//Make your retrofit setup here
//This is the method that calls API using Retrofit
fun callMyRetrofitApi(liveData: MutableLiveData<Your response type here>) {
// Your Api Call with response callback
myRetrofitInstance.apiMethod.enqueue(object : Callback<Your response type here> {
override fun onFailure(call: Call<Your response type here>, t: Throwable) {
}
override fun onResponse(call: Call<Your response type here>, response: Response<Your response type here>) {
liveData.value = response.body()
}
})
}
}

尝试像这样进行设置。

希望对您有所帮助！

Answer 2

使用 LiveData和 Retrofit 在 MVVM 中设计项目的最简单方法是在 ViewModel 类中使用 LiveData，在存储库中使用 Retrofit。

通俗地说，您可以从 ViewModel 类和 ViewModel 类中的存储库获取数据，然后将此数据传递给 MutableLiveData，然后可以通过将其转换为 LiveData 来观察您的视图中的MutableLiveData。

主要活动.java

public class MainActivity extends AppCompatActivity {
private MainViewModel mainViewModel;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_instruction);
mainViewModel = ViewModelProviders.of(this).get(MainViewModel.class);
mainViewModel.init();
mainViewModel.getModelLiveData().observe(this, new Observer<MainResponse>() {
@Override
public void onChanged(@Nullable MainResponse mainResponse) {
// Here you write logic which implements if the ViewModel data changes. 
}}
});
}
}

主视图模型(您的视图模型(

public class MainViewModel extends ViewModel {
private MainRepo mainRepo;
private MutableLiveData<MainResponse> modelMutableLiveData = new MutableLiveData<>();
Disposable disposable;
public MainViewModel() {
}
public MainViewModel(MainRepo mainRepo) {
this.mainRepo = mainRepo;
}
public void init() {
modelMutableLiveData.setValue(mainRepo.callRetrofit().body());
}
public LiveData<MainResponse> getModelLiveData() {
return modelMutableLiveData;
}
}

主存储库(您的存储库类(

public class MainRepository{
public void callRetrofit() {
apiInterface = 
ApiClient.getClient(ApiClient.POST_STATUS_URL).create(ApiInterface.class);
Call<ModelForPostRequest> call = apiInterface.likeItem(modelForPostRequest);
call.enqueue(new Callback<ModelForPostRequest>() {
@Override
public void onResponse(Call<ModelForPostRequest> call, 
Response<ModelForPostRequest> response) {
//do something here
}
@Override
public void onFailure(Call<ModelForPostRequest> call, Throwable t) {
}
});
}}