Question

我试图将一组Room组件注入一个Repository，它本身使用Dagger2注入一个ViewModel（在一个片段中）。

代码如下。

片段：

    do { x <- p ;
         y <- if (pred x) then (foo x) else (bar x) ;
         return (baz x y) }

查看型号：

class MyFragment : Fragment() {
    private var viewModel: MyViewModel? = null

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(MyViewModel::class.java)
        viewModel!!.init()
        viewModel!!.getUser().observe(this, Observer<MyClass?> {...})
    }
    ...
}

我的存储库：

class MyViewModel : ViewModel() {

    @Inject lateinit var myRepo: MyRepository

    private var instance: LiveData<MyClass>? = null

    fun init() {
        DaggerAppComponent.builder()
                .build().daggerInject(this)
        if (this.instance != null) {
            return
        }
        instance = myRepo.getInstance()
    }
}

最后，对于我的匕首课程，我有两个模块：

@Singleton
class MyRepository {
    @Inject lateinit var myDao: MyDao
    @Inject lateinit var executor: Executor

    init {
        DaggerAppComponent.builder().build().daggerInject(this)
    }
}

我的AppComponent：

@Module(includes = [AndroidInjectionModule::class])
abstract class AppModule {

    @Binds
    abstract fun application(app: MyApplication): MyApplication
}


@Module
class DataModule {

    @Inject
    lateinit var application: MyApplication

    val myDatabase = Room.databaseBuilder(application, MyDatabase::class.java, "my-database").build()

    @Provides
    @Singleton
    fun provideRepository(): MyRepository {
        return MyRepository()
    }

    @Provides
    fun provideMyDao(): MyDao {
        return MyDao_Impl(myDatabase)
    }

    @Provides
    fun providesExecutor(): Executor {
        return Executors.newSingleThreadExecutor()
    }

}

Dagger编译得很好，我可以访问@Singleton @Component(modules = [AppModule::class, DataModule::class]) interface AppComponent : AndroidInjector<MyApplication> { fun daggerInject(viewModel: MyViewModel) fun daggerInject(myRepo: MyRepository) @Component.Builder abstract class Builder: AndroidInjector.Builder<MyApplication>() }并构建它。但是DaggerAppComponent是不可访问的（检查类显示它是私有的）和实际注入依赖项所需的dataModule方法一样。结果我得到错误：

daggerInject

我该如何解决这个问题？

Answer 1

inline fun <reified T: ViewModel> AppCompatActivity.createViewModel(crossinline factory: () -> T): T = T::class.java.let { clazz ->
    ViewModelProviders.of(this, object: ViewModelProvider.Factory {
        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
            if(modelClass == clazz) {
                @Suppress("UNCHECKED_CAST")
                return factory() as T
            }
            throw IllegalArgumentException("Unexpected argument: $modelClass")
        }
    }).get(clazz)
}

inline fun <reified T: ViewModel> Fragment.createViewModel(crossinline factory: () -> T): T = T::class.java.let { clazz ->
    ViewModelProviders.of(this, object: ViewModelProvider.Factory {
        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
            if(modelClass == clazz) {
                @Suppress("UNCHECKED_CAST")
                return factory() as T
            }
            throw IllegalArgumentException("Unexpected argument: $modelClass")
        }
    }).get(clazz)
}

和片段：

class MyFragment : Fragment(), Injectable {
    private lateinit var viewModel: MyViewModel

    @Inject lateinit var appComponent: AppComponent 

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = createViewModel { appComponent.myViewModel() }
        viewModel.getUser().observe(this) {...}
    }
    ...
}

查看型号：

class MyViewModel @Inject constructor(private val myRepo: MyRepository): ViewModel() {

    private var instance: LiveData<MyClass>? = myRepo.getInstance()
}

我的存储库：

@Singleton
class MyRepository @Inject constructor(
    private val myDao: MyDao, 
    private val executor: Executor
) {
}

最后，对于我的匕首课程，我有两个模块：

@Module(includes = [AndroidInjectionModule::class])
abstract class AppModule {
    fun application(myApplication: MyApplication): Application = myApplication
}
@Module
abstract class DataModule {
    @Provides
    fun myDatabase(application: Application) = 
        Room.databaseBuilder(application, MyDatabase::class.java, "my-database").build()

    @Provides
    fun myDao(): MyDao = myDatabase.myDao()

    @Provides
    fun providesExecutor(): Executor =
        Executors.newSingleThreadExecutor()
}

我的AppComponent：

@Singleton
@Component(modules = [AppModule::class, DataModule::class])
interface AppComponent : AndroidInjector<MyApplication> {
    @Component.Builder
    abstract class Builder: AndroidInjector.Builder<MyApplication>()

    fun myViewModel(): MyViewModel
}

和AppInjector：

import android.app.Activity
import android.app.Application
import android.os.Bundle
import android.support.v4.app.Fragment
import android.support.v4.app.FragmentActivity
import android.support.v4.app.FragmentManager
import dagger.android.AndroidInjection
import dagger.android.support.AndroidSupportInjection
import dagger.android.support.HasSupportFragmentInjector

/**
 * Helper class to automatically inject fragments if they implement [Injectable].
 */
object AppInjector {
    fun init(myApp: MyApplication) {
        DaggerAppComponent.builder().application(myApp)
            .build().inject(myApp)
        myApp
            .registerActivityLifecycleCallbacks(object : Application.ActivityLifecycleCallbacks {
                override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
                    handleActivity(activity)
                }

                override fun onActivityStarted(activity: Activity) {

                }

                override fun onActivityResumed(activity: Activity) {

                }

                override fun onActivityPaused(activity: Activity) {

                }

                override fun onActivityStopped(activity: Activity) {

                }

                override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle?) {

                }

                override fun onActivityDestroyed(activity: Activity) {

                }
            })
    }

    private fun handleActivity(activity: Activity) {
        if (activity is HasSupportFragmentInjector) {
            AndroidInjection.inject(activity)
        }
        if (activity is FragmentActivity) {
            activity.supportFragmentManager
                .registerFragmentLifecycleCallbacks(
                    object : FragmentManager.FragmentLifecycleCallbacks() {
                        override fun onFragmentCreated(
                            fm: FragmentManager,
                            f: Fragment,
                            savedInstanceState: Bundle?
                        ) {
                            if (f is Injectable) {
                                AndroidSupportInjection.inject(f)
                            }
                        }
                    }, true
                )
        }
    }
}

和

class MyApplication : Application(), HasActivityInjector {
    @Inject
    lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Activity>

    override fun onCreate() {
        super.onCreate()
        AppInjector.init(this)
    }

    override fun activityInjector() = dispatchingAndroidInjector
}

Dagger2方法中未解决的注入方法

1 个答案: