如何在Kotlin中实现Room数据库登录

implementation "androidx.room:room-runtime:2.4.0"
kapt "androidx.room:room-compiler:2.4.0"

@Entity(tableName = "users")
data class User(
    @PrimaryKey val id: Int,
    val username: String,
    val password: String
)

@Dao
interface UserDao {
    @Query("SELECT * FROM users WHERE username = :username AND password = :password")
    fun getUserByUsernameAndPassword(username: String, password: String): User?
}

@Database(entities = [User::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

val appDatabase = Room.databaseBuilder(applicationContext, AppDatabase::class.java, "app-db").build()

val userDao = appDatabase.userDao()
val user = userDao.getUserByUsernameAndPassword(username, password)
if (user != null) {
    // 登录成功
} else {
    // 登录失败
}