安卓。无法实例化 Worker

Question

我想从 Assets 文件夹中的 json 文件预填充我的 Room 数据库。我关注Google Sunflower sample .我复制了 SeedDatabaseWorker 类:

import android.content.Context
import android.util.Log
import androidx.work.Worker
import androidx.work.WorkerParameters
import com.dmitrysimakov.gymlab.data.GymLabDb
import com.dmitrysimakov.gymlab.data.entity.Training
import com.google.gson.Gson
import com.google.gson.reflect.TypeToken
import com.google.gson.stream.JsonReader
import javax.inject.Inject

class SeedDatabaseWorker(val context: Context, workerParams: WorkerParameters) : Worker(context, workerParams) {
    private val TAG = SeedDatabaseWorker::class.java.simpleName

    @Inject lateinit var database: GymLabDb

    override fun doWork(): Worker.Result {
        val plantType = object : TypeToken<List<Training>>() {}.type
        var jsonReader: JsonReader? = null

        return try {
            val inputStream = context.assets.open("training.json")
            jsonReader = JsonReader(inputStream.reader())
            val plantList: List<Training> = Gson().fromJson(jsonReader, plantType)
            database.trainingDao().insert(plantList)
            Worker.Result.SUCCESS
        } catch (ex: Exception) {
            Log.e(TAG, "Error seeding database", ex)
            Worker.Result.FAILURE
        } finally {
            jsonReader?.close()
        }
    }
}

我正在使用 Dagger 2，所以我没有这样做:Sunflower AppDatabase ，我这样做:

import android.arch.persistence.db.SupportSQLiteDatabase
import android.arch.persistence.room.Room
import android.arch.persistence.room.RoomDatabase
import androidx.work.OneTimeWorkRequestBuilder
import androidx.work.WorkManager
import com.dmitrysimakov.gymlab.GymLabApp
import com.dmitrysimakov.gymlab.data.GymLabDb
import com.dmitrysimakov.gymlab.workers.SeedDatabaseWorker
import dagger.Module
import dagger.Provides
import javax.inject.Singleton

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

    @Singleton
    @Provides
    fun provideDb(app: GymLabApp): GymLabDb {
        return Room
                .databaseBuilder(app, GymLabDb::class.java, "gymlab.db")
                .addCallback(object : RoomDatabase.Callback() {
                    override fun onCreate(db: SupportSQLiteDatabase) {
                        super.onCreate(db)
                        val request = OneTimeWorkRequestBuilder<SeedDatabaseWorker>().build()
                        WorkManager.getInstance().enqueue(request)
                    }
                })
                .fallbackToDestructiveMigration()
                .build()
    }

    @Singleton
    @Provides
    fun provideTrainingDao(db: GymLabDb) = db.trainingDao()
}

但是我无法注入(inject)尚未创建的数据库。那么，如何访问 dao？

Answer 1

问题是我无法将我的数据库注入(inject)到 Worker 中。我在这里找到了解决方案:AndroidWorkerInjection