搞了一天终于搞出来了……一直不成功好像是因为 DB 对象没有写成单例。
Dao：
@Dao
interface ItemDao {
@Query("SELECT * FROM item")
fun getAll(): LiveData<List<Item>>
@Query("SELECT * FROM item WHERE uid IN (:itemIds)")
fun loadAllByIds(itemIds: IntArray): List<Item>
@Insert
fun insert(items: Item): Long
}
AppDatabase
@Database(entities = [Item::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
abstract fun itemDao(): ItemDao
}
DBUtils
class DBUtils private constructor() {
companion object {
val instance: DBUtils by lazy { DBUtils() }
private lateinit var context: Context
private val database: AppDatabase by lazy(LazyThreadSafetyMode.SYNCHRONIZED) {
Room.databaseBuilder(context, AppDatabase::class.java, "clipboard_manager.db").build()
}
fun getDatabase(context: Context): AppDatabase {
this.context = context.applicationContext
return database
}
}
}
使用
DBUtils.getDatabase(applicationContext).itemDao().getAll().observe(
this, { items ->
toast(items.toString())
}
)
