1). 简介

Room persistence库为SQLite提供了一个抽象层，以便在利用SQLite的全部功能的同时实现更强大的数据库访问。

2). 依赖

buildscript {  ext.room_version = "1.1.0"}dependencies {  // Room 使用  implementation "android.arch.persistence.room:runtime:$room_version"  annotationProcessor "android.arch.persistence.room:compiler:$room_version"  // optional - RxJava support for Room  implementation "android.arch.persistence.room:rxjava2:$room_version"  // optional - Guava support for Room, including Optional and ListenableFuture  implementation "android.arch.persistence.room:guava:$room_version"  // Test helpers  testImplementation "android.arch.persistence.room:testing:$room_version"  // Kotlin  kapt "android.arch.persistence.room:compiler:$room_version"}

3). 数据实体类

* 实体类 * Created by mazaiting on 2018/7/25. */@Entitydata class User(       @PrimaryKey        val uid: Int,       @ColumnInfo(name = "first_name")       var firstName: String,       @ColumnInfo(name = "last_name")       var lastName: String)

4). 用户DAO类

/** * 用户DAO类 * Created by mazaiting on 2018/7/25. */@Daointerface UserDao {  @Query("SELECT * FROM user")  fun getAll(): List
     
        @Query("SELECT * FROM user  WHERE uid IN (:userIds)")  fun loadAllByIds(userIds: IntArray): List
      
         @Query("SELECT * FROM user WHERE first_name LIKE :first AND last_name LIKE :last LIMIT 1")  fun findByName(first: String, last: String): User  @Insert  fun insertAll(users: List
       
        )  // 可变参数//  fun insertAll(vararg users: User)  @Delete  fun delete(user: User)  @Update  fun update(user: User)}
       
      
     

5). 数据库类

/** * 数据库类 * Created by mazaiting on 2018/7/25. */@Database(entities = arrayOf(User::class), version = 1)abstract class AppDatabase : RoomDatabase() {  // 获取DAO  abstract fun userDao(): UserDao}

6). 创建数据库

btn_create_db.setOnClickListener {      val db = Room.databaseBuilder(applicationContext, AppDatabase::class.java, "TEST").build()      userDao = db.userDao()    }

7). 新增数据

对数据的操作必须在子线程中

btn_insert.setOnClickListener {      Thread(Runnable {        val users = (0..10).map { User(it, "first$it", "last$it") }        userDao.insertAll(users)      }).start()    }

8). 查询数据

btn_find_all.setOnClickListener {      Thread(Runnable {        userDao.getAll().forEach { L.e(it.toString()) }      }).start()    }    btn_find_id.setOnClickListener {      Thread(Runnable {        userDao.loadAllByIds(intArrayOf(0, 1, 2, 3, 4)).forEach { L.e(it.toString()) }      }).start()    }    btn_find_name.setOnClickListener {      Thread(Runnable {        L.e(userDao.findByName("first1", "last1").toString())      }).start()    }

9). 更新数据

btn_update.setOnClickListener {      Thread(Runnable {        val user = userDao.findByName("first1", "last1")        user.firstName = "ma"        user.lastName = "zaiting"        userDao.update(user)        userDao.loadAllByIds(intArrayOf(1)).forEach { L.e(it.toString()) }      }).start()    }

10). 删除数据

btn_delete.setOnClickListener {      Thread(Runnable {        userDao.delete(userDao.loadAllByIds(intArrayOf(0))[0])      }).start()    }

11).

12).