如何在dagger2中重新提供和对象的单例数据库实例

如何解决如何在dagger2中重新提供和对象的单例数据库实例

我想到了一个有关匕首2的问题。
我提供数据库实例的单例对象，并在项目中使用它。
有一次我具有备份和还原数据库的功能。
正如您在restore（）方法中看到的那样，我必须在写入文件之前关闭数据库实例。
此外，在应用程序中，我想使用数据库的这个单例实例，它会引起诸如“连接已关闭的异常”之类的麻烦
如何重新打开该数据库？
还是如何在备份后立即提供此单例实例？
我想到了这些解决方案：

1. 从匕首2中排除数据库实例，并将其作为实用程序手动注入

2. 从dagger2的提供方法中删除@singleTon->，但它会导致数据库锁定异常和将来不必要的数据库对象提供。
   这是我的代码：
   

   @Module(includes = [WorkerBindingModule::class])
   class UserModule {
   
   @Singleton
   @Provides
   fun provideDb(app: DistApplication): DistributionDataBase {
   val storage = Storage(app)
   
   return Room
       .databaseBuilder(app.applicationContext,DistributionDataBase::class.java,"distributionDB.db") //TODO for multi User //"distributionDB_${storage.getCurrentUserId()}.db"
       .fallbackToDestructiveMigration()
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_1_2)
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_2_3)
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_3_4)
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_4_5)
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_5_6)
       .addMigrations(DistributionDataBaseMigrations.MIGRATION_6_7)
       .build()
      }
    }
   

还原方法：

 fun restoreDatabase(activity: FragmentActivity,appDatabase: DistributionDataBase?,backup: DatabaseBackupModel,permissionRequestCode: Int,rootView: View,listener: DatabaseBackupListener) {
    val permission = ActivityCompat.checkSelfPermission(activity,Manifest.permission.WRITE_EXTERNAL_STORAGE)
    if (permission == PackageManager.PERMISSION_GRANTED) {
        val backupDirectory = File(
            Environment.getExternalStorageDirectory(),GeneralUtil.Paths.BACKUPS_PATH
        )
        if (!backupDirectory.exists()) {
            backupDirectory.mkdirs()
        }
        
        val backupTempDirectory = File(
            Environment.getExternalStorageDirectory(),GeneralUtil.Paths.BACKUPS_PATH_TEMP
        )
        if (!backupTempDirectory.exists()) {
            backupTempDirectory.mkdirs()
        } else {
            GeneralUtil.deleteFiles(GeneralUtil.Paths.BACKUPS_PATH_TEMP,".*",true)
        }
        
        val zipFilePath = backupDirectory.absolutePath + File.separator + backup.fileName
        GeneralUtil.unzipFile(zipFilePath,backupTempDirectory.absolutePath)
        
        appDatabase?.close()
        
        val db = File(backupTempDirectory.absolutePath,"distributionDB.db")
        val dbShm = File(db.parent,"distributionDB.db-shm")
        val dbWal = File(db.parent,"distributionDB.db-wal")
        val metadataFile = File(db.parent,BACKUP_METADATA_FILE_NAME)
        val metadata = readMetadata(metadataFile)
        val db2 = activity.getDatabasePath("distributionDB.db")
        val dbShm2 = File(db2.parent,"distributionDB.db-shm")
        val dbWal2 = File(db2.parent,"distributionDB.db-wal")
        
        try {
            db2.delete()
            dbShm2.delete()
            dbWal2.delete()
            EncryptionServices.decryptFile(db,db2,metadata.salt,metadata.iv,"sepidar${metadata.versionName}")
            dbShm.copyTo(dbShm2)
            dbWal.copyTo(dbWal2)
        } catch (e: Exception) {
            Timber.e(e.toString())
        }
        db.delete()
        dbShm.delete()
        dbWal.delete()
        Snackbar.make(rootView,activity.getString(R.string.database_restore_success),Snackbar.LENGTH_LONG)
            .show()
        listener.onFinish()
    } else {
        Snackbar.make(rootView,activity.getString(R.string.allow_access_to_storage),Snackbar.LENGTH_LONG)
            .setAction(activity.getString(R.string.allow)) {
                ActivityCompat.requestPermissions(
                    activity,arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),permissionRequestCode
                )
            }
            .show()
    }
}

MainActivity onCreate：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    AndroidInjection.inject(this)
    DistApplication.getInstance()
        .userComponent()
    }