android - Dagger 2.10/2.11 注入(inject) Activity 失败

Question

我一直在尝试将 Activity 注入(inject)到 ViewUtils 类中，但没有成功。我关注了几篇不同的帖子，但我似乎无法理解我在实现过程中遗漏了什么。

我知道这可能是下面帖子的重复，对此我深表歉意，但老实说，我看不出我错过了什么。这些是我找到的帖子:

• Dagger 2.10 Android subcomponents and builders
• How to create custom scoped modules in dagger 2.10
• https://google.github.io/dagger/subcomponents.html

我的实现如下:

应用组件

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

    @Component.Builder abstract class Builder extends AndroidInjector.Builder<EmblyApp> {}
}

ActivityBindingModule

@Module public abstract class ActivityBindingModule {

    @ContributesAndroidInjector
    abstract LoginActivity loginActivity();
}

登录子组件

@Subcomponent(modules = LoginSubcomponent.LoginActivityModule.class)
public interface LoginSubcomponent extends AndroidInjector<LoginActivity> {

    @Subcomponent.Builder abstract class Builder extends AndroidInjector.Builder<LoginActivity> {}

    @Module abstract class LoginActivityModule {

        @Binds abstract Activity bindActivity(LoginActivity activity);

        @Provides @ActivityScope static ViewUtils viewUtils(Activity activity) {
            return new ViewUtils(activity);
        }
    }
}

ViewUtils

public class ViewUtils {

    private final Activity activity;

    @Inject public ViewUtils(Activity activity) {
        this.activity = activity;
    }
}

我得到的错误是:

Error:(14, 22) error: [dagger.android.AndroidInjector.inject(T)] android.app.Activity cannot be provided without an @Inject constructor or from an @Provides-annotated method.
android.app.Activity is injected at
com.emblyapp.app.ui.helpers.ViewUtils.<init>(activity)
com.emblyapp.app.ui.helpers.ViewUtils is injected at
com.emblyapp.app.ui.authentication.login.LoginActivity.viewUtils
com.emblyapp.app.ui.authentication.login.LoginActivity is injected at
dagger.android.AndroidInjector.inject(arg0)

这里有什么问题？感谢您的帮助!

编辑:我忘了说我的 LoginActivity 有 AndroidInjection 注入(inject)

@Override protected void onCreate(Bundle savedInstanceState) {
        AndroidInjection.inject(this);
        super.onCreate(savedInstanceState);
    }

Answer 1

如 dagger android documentation 中所述:

Pro-tip: If your subcomponent and its builder have no other methods or supertypes than the ones mentioned in step #2, you can use @ContributesAndroidInjector to generate them for you. Instead of steps 2 and 3, add an abstract module method that returns your activity, annotate it with @ContributesAndroidInjector, and specify the modules you want to install into the subcomponent. If the subcomponent needs scopes, apply the scope annotations to the method as well.

因此，我们可以摆脱 LoginSubcomponent 并在 ActivityBindingModule 中执行以下更改:

    @Module
    public abstract class ActivityBindingModule {

        @ActivityScope
        @ContributesAndroidInjector(modules = LoginActivityModule.class)
        abstract LoginActivity loginActivity();
    }

LoginActivityModule.java

    @Module
    abstract class LoginActivityModule {

        @Binds
        abstract Activity bindActivity(LoginActivity activity);

        @Provides
        @ActivityScope
        static ViewUtils viewUtils(Activity activity) {
            return new ViewUtils(activity);
        }
    }

您的自定义应用程序类:

    public class MyApp extends DaggerApplication {

        @Inject
        DispatchingAndroidInjector dispatchingActivityInjector;

        @Override
        protected AndroidInjector applicationInjector() {
            return DaggerAppComponent.builder().create(this);
        }

    }