我刚开始使用Dagger 2,但我在网上发现了成千上万的指南,每个指南都有不同的实现方式,现在我有些困惑。因此,基本上这是我目前所写的内容:
AppModule.java:
@Module
public class AppModule {
Application mApplication;
public AppModule(Application application) {
mApplication = application;
}
@Provides
@Singleton
Application providesApplication() {
return mApplication;
}
}
DataModule.java:
@Module
public class DataModule {
private static final String BASE_URL = "http://beta.fridgewizard.com:9001/api/";
@Provides
@Singleton
NetworkService provideNetworkService() {
return new NetworkService(BASE_URL);
}
@Provides
@Singleton
SharedPreferences provideSharedPreferences(Application app) {
return PreferenceManager.getDefaultSharedPreferences(app);
}
}
PrefsModel.java:
@Module(includes = DataModule.class)
public class PrefsModel {
@Provides
@Singleton
QueryPreferences provideQuery(SharedPreferences prefs) {
return new QueryPreferences(prefs);
}
}
AppComponent.java(由于在演示者中需要QueryPreferences对象,因此我将其公开,希望以此方式是正确的):
@Singleton
@Component(modules = {AppModule.class, DataModule.class, PrefsModel.class})
public interface AppComponent {
void inject(HomeFragment homeFragment);
QueryPreferences preferences();
NetworkService networkService();
}
然后,我有了FwApplication.java:
public class FwApplication extends Application {
private static final String TAG = "FwApplication";
private NetworkService mNetworkService;
private AppComponent mDataComponent;
@Override
public void onCreate() {
super.onCreate();
buildComponentAndInject();
}
public static AppComponent component(Context context) {
return ((FwApplication) context.getApplicationContext()).mDataComponent;
}
public void buildComponentAndInject() {
mDataComponent = DaggerComponentInitializer.init(this);
}
public static final class DaggerComponentInitializer {
public static AppComponent init(FwApplication app) {
return DaggerAppComponent.builder()
.appModule(new AppModule(app))
.dataModule(new DataModule())
.build();
}
}
}
最后,我为演示者添加了另一个模块:
@Module
public class PresenterModule {
@Provides
Presenter<FwView> provideHomePresenter(NetworkService networkService) {
return new HomePresenterImpl(networkService);
}
@Provides
Presenter<FwView> provideSearchPresenter(NetworkService networkService) {
return new SearchPresenterImpl(networkService);
}
}
还有以下组件(由于我无法在此处添加范围内的依赖项,因此返回错误):
@Component(dependencies = AppComponent.class, modules = PresenterModule.class)
public interface PresenterComponent {
void inject(HomePresenterImpl presenter);
}
因此,对于在线阅读文档,我有几个不清楚的问题:
编辑-修复:
HomeFragment.java:
public class HomeFragment extends Fragment {
private static final String TAG = "FW.HomeFragment";
@Inject
HomePresenterImpl mHomePresenter;
public static HomeFragment newInstance() {
return new HomeFragment();
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FwApplication.component(getActivity()).inject(this);
}
然后,我以这种方式修改了presenter构造函数:
@Inject
public HomePresenterImpl(NetworkService networkService) {
mNetworkService = networkService;
mInteractor = new InteractorImpl(mNetworkService);
}
然后,将自动注入NetworkService。
我想知道这样是否正确,因为我必须调用我需要的每个片段,每个片段都需要以与以下代码上方相同的方式构造的演示者:
FwApplication.component(getActivity()).inject(this);
您正在混淆。要提供演示者,您应该切换到以下内容:
如果可能,请使用构造函数注入。它将使事情变得容易得多
public class HomePresenterImpl {
@Inject
public HomePresenterImpl(NetworkService networkService) {
// ...
}
}
要提供接口,请使用此构造函数注入,并取决于实现:
Presenter<FwView> provideHomePresenter(HomePresenterImpl homePresenter) {
return homePresenter;
}
这样,您不必自己调用任何构造函数。并实际注入演示者...
public class MyFragment extends Fragment {
@Inject
Presenter<FwView> mHomePresenter;
public void onCreate(Bundle xxx) {
// simplified. Add your modules / Singleton component
PresenterComponent component = DaggerPresenterComponent.create().inject(this);
}
}
这样,您将注入事物。请仔细阅读并尝试理解它。这将解决您的主要问题,但是您仍然无法从同一模块(在同一范围内)提供2个相同类型的演示者
// DON'T
@Provides
Presenter<FwView> provideHomePresenter(NetworkService networkService) { /**/ }
@Provides
Presenter<FwView> provideSearchPresenter(NetworkService networkService) { /**/ }
这将不工作。您不能提供2个相同类型的对象。它们是无法区分的。看看@Qualifiers
像@Named
如果你确信这是你想要的路要走。
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