带有 Kotlin 的 Dagger 2，在 ApplicationComponent 中使用泛型返回类型

Question

我想 return 类型的泛型被子图暴露，问题出在自动生成的 java-类，我尝试做一些事情，但是解决它的一种方法是从 AppComponent 和 return 简单对象中删除通用类型。还有更多"right"方法吗？

这是 AppComponent

@Singleton
@Component(modules = arrayOf(ApplicationModule::class))
interface ApplicationComponent {
    fun inject(activity: BaseActivity<MvpView, MvpPresenter<MvpView>>)

    //...
    fun dataBase(): Database<Realm>
}

这是 ApplicationModule 中的函数

@Provides @Singleton fun provideDatabase(@AppContext context: App): Database<Realm> {
    Realm.init(context)
    val config = RealmConfiguration.Builder()
            .deleteRealmIfMigrationNeeded()
            .name("db")
            .build()
    Realm.setDefaultConfiguration(config)
    return RealmDatabase(Realm.getDefaultInstance())
}

然后我想接收我的数据库

@Provides @ActivityScope fun provideDich(database: Database<Realm>) = Someobject(database)

然后我看到日志说：

**Error:com.test.data.storage.Database<? extends io.realm.Realm> cannot be provided without an @Provides-annotated method.**

因为dagger2生成这样的工厂还有java个masks

    public final class Logout_Factory implements Factory<Logout> {
  private final MembersInjector<Logout> logoutMembersInjector;

  private final Provider<SessionStorage.CloudStorage> arg0Provider;

  private final Provider<Database<? extends Realm>> arg1Provider;

  public Logout_Factory(
      MembersInjector<Logout> logoutMembersInjector,
      Provider<SessionStorage.CloudStorage> arg0Provider,
      Provider<Database<? extends Realm>> arg1Provider) {
    assert logoutMembersInjector != null;
    this.logoutMembersInjector = logoutMembersInjector;
    assert arg0Provider != null;
    this.arg0Provider = arg0Provider;
    assert arg1Provider != null;
    this.arg1Provider = arg1Provider;
  }

  @Override
  public Logout get() {
    return MembersInjectors.injectMembers(
        logoutMembersInjector, new Logout(arg0Provider.get(), arg1Provider.get()));
  }

  public static Factory<Logout> create(
      MembersInjector<Logout> logoutMembersInjector,
      Provider<SessionStorage.CloudStorage> arg0Provider,
      Provider<Database<? extends Realm>> arg1Provider) {
    return new Logout_Factory(logoutMembersInjector, arg0Provider, arg1Provider);
  }
}

Answer 1

我遇到了同样的问题，我找到了解决方案。

您需要在 @Provide 方法 return 类型中声明 @JvmWildcard。

@Provides 
@Singleton 
fun provideDatabase(@AppContext context: App): Database<@JvmWildcard Realm> {
    Realm.init(context)
    val config = RealmConfiguration.Builder()
            .deleteRealmIfMigrationNeeded()
            .name("db")
            .build()
    Realm.setDefaultConfiguration(config)
    return RealmDatabase(Realm.getDefaultInstance())
}

带有 Kotlin 的 Dagger 2，在 ApplicationComponent 中使用泛型返回类型

Dagger 2 with Kotlin, returning type with generic in ApplicationComponent

java

generics

android

kotlin

dagger-2