1. 首先，要在应用的 build.gradle 文件中添加以下依赖项：

dependencies {
    def room_version = "2.3.0"

    implementation "androidx.room:room-runtime:$room_version"
    kapt "androidx.room:room-compiler:$room_version"
    implementation "androidx.room:room-ktx:$room_version"

    // optional - Kotlin Extensions and Coroutines support for Room
    implementation "androidx.room:room-ktx:$room_version"

    // optional - RxJava3 support for Room
    implementation "androidx.room:room-rxjava3:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "androidx.room:room-guava:$room_version"

    // optional - Testing Room migrations
    testImplementation "androidx.room:room-testing:$room_version"

    // optional - Paging 3 Integration
    implementation "androidx.room:room-paging:2.4.0-alpha02"
}

2.创建一个实体类来表示数据库中的表：

@Entity(tableName = "user")
data class User(
    @PrimaryKey val id: Int,
    val name: String,
    val age: Int
)

3.创建一个 DAO 接口来定义数据访问：

@Dao
interface UserDao {
    @Query("SELECT * FROM user")
    fun getAll(): List

    @Query("SELECT * FROM user WHERE id = :userId")
    fun getUserById(userId: Int): User

    @Insert
    fun insertAll(vararg users: User)

    @Delete
    fun delete(user: User)
}

4.创建数据库类，并将实体类和 DAO 接口作为参数传递：

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

5.使用数据库：

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

val userDao = db.userDao()
val users = userDao.getAll()
val user = userDao.getUserById(1)