Question

我正在MVVM和Dagger 2中运行小型Android应用程序。但是当我只有一个Activity和两个Fragments时，我不知道如何正确使用Dagger 2。这两个片段都是ViewModels的所有者。我已经将ViewModelProvider注入Fragment，但是我对此解决方案仍然感到困惑。也许有人会改善我的代码？

活动：

public class MainActivity extends DaggerAppCompatActivity {

private static final String TAG = "MainActivity";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    BottomNavigationView navView = findViewById(R.id.nav_view);

    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    NavigationUI.setupWithNavController(navView, navController);
}

}

FirstFragment ：

public class EventsFragment extends DaggerFragment {

private static final String TAG = "EventsFragment";
private EventsViewModel eventsViewModel;
private final EventsAdapter adapter = new EventsAdapter();
private List<Event> events = new ArrayList<>();

@Inject
ViewModelProviderFactory viewModelProviderFactory;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    eventsViewModel = ViewModelProviders.of(this, viewModelProviderFactory).get(EventsViewModel.class);
    View root = inflater.inflate(R.layout.fragment_events, container, false);

    RecyclerView recyclerView = root.findViewById(R.id.events_recycler_view);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    recyclerView.setHasFixedSize(true);
    recyclerView.setAdapter(adapter);

    getEvents();

    return root;
}

第二个片段：

public class ScheduleFragment extends DaggerFragment {

private ScheduleViewModel scheduleViewModel;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    scheduleViewModel = ViewModelProviders.of(this).get(ScheduleViewModel.class);
    View root = inflater.inflate(R.layout.fragment_schedule, container, false);

    return root;
}

@Override
public void onAttach(Context context) {
    AndroidSupportInjection.inject(this);
    super.onAttach(context);
}
}

在这种情况下，两个片段都可以工作，但是我只能将ViewModelFactory注入其中一个。如果我将其注入第二个对象：错误：找不到符号类DaggerAppComponent

ActivityBuildersModule：

@Module
public abstract class ActivityBuildersModule {

@ContributesAndroidInjector(modules = FragmentBuildersModule.class)
abstract MainActivity contributeMainActivity();
}

AppComponent：

   @Singleton
   @Component(
    modules = {
            AndroidSupportInjectionModule.class,
            ActivityBuildersModule.class,
            AppModule.class,
            ViewModelFactoryModule.class
    }
    )
    public interface AppComponent extends AndroidInjector<BaseApplication> {

@Component.Builder
interface Builder {

    @BindsInstance
    Builder application(Application application);

    AppComponent build();
}

}

FragmentBuildersModule：

 @Module
 public abstract class FragmentBuildersModule {

@ContributesAndroidInjector(
        modules = {ViewModelModule.class, EventsModule.class}
)
abstract EventsFragment contributeEventsFragment();

@ContributesAndroidInjector(
        modules = {ViewModelModule.class}
)
abstract ScheduleFragment contributeScheduleFragment();
}

ViewModelFactory：

@Module
public abstract class ViewModelFactoryModule {

@Binds
public abstract ViewModelProvider.Factory bindViewModelFactory(ViewModelProviderFactory modelProviderFactory);
}

ViewModelKey：

@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@MapKey
public @interface ViewModelKey {
Class<? extends ViewModel> value();
}

ViewModelModule：

@Module

公共抽象类ViewModelModule {

@Binds
@IntoMap
@ViewModelKey(EventsViewModel.class)
public abstract ViewModel bindEventsViewModel(EventsViewModel eventsViewModel);

@Binds
@IntoMap
@ViewModelKey(ScheduleViewModel.class)
public abstract ViewModel bindScheduleViewmodel(ScheduleViewModel scheduleViewModel);

BaseApplication：

public class BaseApplication extends DaggerApplication {


@Override
protected AndroidInjector<? extends DaggerApplication> applicationInjector() {
    return DaggerAppComponent.builder().application(this).build();
}

Answer 1

就像在第一个片段中那样做。试试这个



public class ScheduleFragment extends DaggerFragment {

private ScheduleViewModel scheduleViewModel;

@Inject
ViewModelProviderFactory viewModelProviderFactory;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    scheduleViewModel = ViewModelProviders.of(this, viewModelProviderFactory).get(ScheduleViewModel.class);
    View root = inflater.inflate(R.layout.fragment_schedule, container, false);

    return root;
}
}

还有一种通过在AppModule中添加这种方法来提供Api的方法

@Singleton
    @Provides
    public RemoteApi provideRemoteApi(){
        return Retrofit.Builder()
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .baseUrl(Constants.API_BASE_URL)
            .build()
            .create(RemoteApi::class.java)
    }

您应该在其中用Api类替换RemoteApi。

匕首2，底部导航和注入

1 个答案: