Android(安卓)数据存储 Room

2019独角兽企业重金招聘Python工程师标准>>>

本来想查一下Android最新的数据存储知识，意外发现：官方推荐使用Room代替SQLite，那就学习一下把。

Room由三部分组成

Database
Entity
DAO

安装

详见这里

Database

@Database(entities = {User.class}, version = 1)public abstract class AppDatabase extends RoomDatabase {    public abstract UserDao userDao();}

Entity

@Entitypublic class User {    @PrimaryKey    public int uid;    @ColumnInfo(name = "first_name")    public String firstName;    @ColumnInfo(name = "last_name")    public String lastName;}

DAO

@Daopublic interface UserDao {    @Query("SELECT * FROM user")    List getAll();    @Query("SELECT * FROM user WHERE uid IN (:userIds)")    List loadAllByIds(int[] userIds);    @Query("SELECT * FROM user WHERE first_name LIKE :first AND " +           "last_name LIKE :last LIMIT 1")    User findByName(String first, String last);    @Insert    void insertAll(User... users);    @Delete    void delete(User user);}

使用

AppDatabase db = Room.databaseBuilder(getApplicationContext(),        AppDatabase.class, "database-name").build();

下面是官方提到的注意事项:

Note: If your app runs in a single process, you should follow the singleton design pattern when instantiating an AppDatabase object. Each RoomDatabase instance is fairly expensive, and you rarely need access to multiple instances within a single process.

If your app runs in multiple processes, include enableMultiInstanceInvalidation() in your database builder invocation. That way, when you have an instance of AppDatabase in each process, you can invalidate the shared database file in one process, and this invalidation automatically propagates to the instances of AppDatabase within other processes.

参考文献：

Save data in a local database using Room
Android Room with a view（需要借助代理）
Android Persistence（需要借助代理）
Android Architecture Components
Save data using SQLite
Android Sunflower

转载于:https://my.oschina.net/u/219974/blog/2877228

Room由三部分组成

安装

Database

Entity

DAO

使用

参考文献：

更多相关文章

随机推荐