java - Dagger 2 - 提供应用程序类

Question

我正在尝试使用 Dagger 2 注入(inject)我的应用程序类 MyApplication，因为我在不同的地方使用它。这是我使用 Dagger 2.11

的设置

MyApplication.java

public class MyApplication extends Application  implements HasActivityInjector {

  @Inject
  DispatchingAndroidInjector<Activity> dispatchingAndroidInjector;

  @Override
  public void onCreate() {
    super.onCreate();
    AppInjector.init(this);
  }

  @Override
  public DispatchingAndroidInjector<Activity> activityInjector() {
    return dispatchingAndroidInjector;
  }
}

AppInjector.java

public class AppInjector {

  public static void init(MyApplication application){

    //Initialize dagger and inject the application
    DaggerAppComponent.builder().application(application).build().inject(application);

    application.registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
      @Override
      public void onActivityCreated(Activity activity, Bundle aBundle) {
        handleActivity(activity);
      }

      @Override
      public void onActivityStarted(Activity activity) {

      }

      @Override
      public void onActivityResumed(Activity activity) {

      }

      @Override
      public void onActivityPaused(Activity activity) {

      }

      @Override
      public void onActivityStopped(Activity activity) {

      }

      @Override
      public void onActivitySaveInstanceState(Activity activity, Bundle aBundle) {

      }

      @Override
      public void onActivityDestroyed(Activity activity) {

      }
    });
  }

  private static void handleActivity(Activity activity){
    if(activity instanceof HasSupportFragmentInjector ){
        AndroidInjection.inject(activity);
    }
    if (activity instanceof FragmentActivity){
      ((FragmentActivity) activity).getSupportFragmentManager()
              .registerFragmentLifecycleCallbacks(
                      new FragmentManager.FragmentLifecycleCallbacks() {
                        @Override
                        public void onFragmentCreated(FragmentManager fm, Fragment f,
                                                      Bundle savedInstanceState) {
                          if (f instanceof Injectable) {
                            Log.i("LifecycleCallbacks", "injected:" + f);

                            AndroidSupportInjection.inject(f);
                          }
                        }
                      }, true);
    }
  }

AppComponent.java

@Singleton
@Component(modules = {
        AndroidInjectionModule.class,
        ActivityBuilder.class,
        AppModule.class
})

public interface AppComponent {
  @Component.Builder
  interface Builder {
    @BindsInstance Builder application(Application application);
    AppComponent build();
  }

  void inject(MyApplication application);
}

但是，每次我尝试在构造函数中使用 @Inject MyApplication application 时，dagger 都会抛出一个错误，指出没有 @Provides 就无法提供它

此外，我不确定我是否应该在所有地方使用该应用程序，而只使用它的上下文？如果是这样，我将如何提供 Context？

Answer 1

看看您的生成器...

@Component.Builder
interface Builder {
--> @BindsInstance Builder application(Application application);
    AppComponent build();
}

Dagger 只知道你的 Application，你永远不会提到 MyApplication，因此注入(inject)它会失败。

---

我不知道为什么你必须专门注入(inject) MyApplication，但最简单的解决方案是将其更改为绑定(bind)你的 MyApplication ...

@Component.Builder
interface Builder {
    @BindsInstance Builder application(/** --> */ MyApplication application);
    AppComponent build();
}

然后 Dagger 知道 MyApplication 但不知道 Application。要解决此问题，您只需添加一个绑定(bind)其他类型的模块，这很容易，因为您具有子类型...例如

@Module interface AppModule { // could also be an abstract class
  @Binds Application bindApplication(MyApplication application);

  // if you also want to bind context
  @Binds Context bindContext(MyApplication application);
}

只需将此模块添加到您的组件即可。