1.实体类
使用 @Entity 注解创建实体类：

@Entity
data class User(var name: String, var age: Int) {
    /**
     * 主键
     */
    @PrimaryKey(autoGenerate = true)
    var id: Long = 0
}

2.数据访问对象
使用@Dao注解创建数据访问对象：

@Dao
interface UserDao {
    @Insert
    fun addUser(user: User): Long

    @Update
    fun updateUser(user: User)

    @Delete
    fun deleteUser(user: User)

    @Query("delete from User where name = :name")
    fun deleteUserByName(name: String)

    @Query("select * from User")
    fun getUsers(): List<User>

    @Query("select * from User where age > :age")
    fun getUsersByAge(age: Int): List<User>
}

3.数据库管理
使用@Database注解创建数据库管理：

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

    companion object {
        private var instance: AppDatabase? = null

        @Synchronized
        fun getDatabase(context: Context): AppDatabase {
            instance?.let {
                return it
            }
            return Room.databaseBuilder(
                context.applicationContext,
                AppDatabase::class.java,
                "app_database"
            ).build().apply {
                instance = this
            }
        }
    }
}

MainActivity：

    private fun initView() {
        mAddBtn = findViewById(R.id.first_add_btn)
        mUpdateBtn = findViewById(R.id.first_update_btn)
        mDeleteBtn = findViewById(R.id.first_delete_btn)
        mSelectBtn = findViewById(R.id.first_select_btn)
        mContentTv = findViewById(R.id.first_content_tv)

        // 准备数据
        val userDao = AppDatabase.getDatabase(this).userDao()
        val user = User("Tom", 18)

        mAddBtn.setOnClickListener {
            thread {
                user.id = userDao.addUser(user)
            }
        }

        mUpdateBtn.setOnClickListener {
            thread {
                user.age = 20
                userDao.updateUser(user)
            }
        }

        mDeleteBtn.setOnClickListener {
            thread {
                userDao.deleteUser(user)
            }
        }

        mSelectBtn.setOnClickListener {
            thread {
                userDao.getUsers().forEach {
                    Log.d("MainActivity", "用户：${it.id}\t${it.name}\t${it.age}")
                }
            }
        }
    }