如何在第一次运行时填充 Android Room 数据库表? [英] How to populate Android Room database table on first run?

问题描述

在 SQLiteOpenHelper 中有一个 onCreate(SQLiteDatabase ...) 方法，我用来用一些初始数据填充数据库表.

In SQLiteOpenHelper there is a onCreate(SQLiteDatabase ...) method which i used to populate database tables with some initial data.

有没有办法先将一些数据插入到 Room 数据库表中应用运行?

Is there a way to insert some data into Room database table on first app run?

推荐答案

更新

您可以通过 3 种方式执行此操作:重要检查此迁移详细信息

You can do this in 3 ways: important check this for migration details

1- 从导出的资产架构中填充您的数据库

1- Populate your database from exported asset schema

Room.databaseBuilder(appContext, AppDatabase.class, "Sample.db")
    .createFromAsset("database/myapp.db")
    .build();

2- 从文件中填充您的数据库

2- Populate your database from file

Room.databaseBuilder(appContext, AppDatabase.class, "Sample.db")
    .createFromFile(new File("mypath"))
    .build();

3- 您可以在创建数据库后运行脚本或使用 RoomDatabase.Callback 打开数据库时运行脚本，该类在最新版本的 Room 库中可用.

3- You can run scripts after database is created or run every time database is opened using RoomDatabase.Callback, this class is available in the latest version of the Room library.

你需要实现RoomDatabase.Callback的onCreate和onOpen方法并添加到RoomDatabase.Builder如下图.

You need to implement onCreate and onOpen method of RoomDatabase.Callback and add it to RoomDatabase.Builder as shown below.

yourDatabase = Room.databaseBuilder(context, YourDatabase.class, "your db")
    .addCallback(rdc)
    .build();

RoomDatabase.Callback rdc = new RoomDatabase.Callback() {
    public void onCreate (SupportSQLiteDatabase db) {
        // do something after database has been created
        
    }
    public void onOpen (SupportSQLiteDatabase db) {
        // do something every time database is open
     
    }
};

参考

您可以在 RoomDatabase.Callback 方法中使用 Room DAO 本身来填充数据库.有关完整示例，请参阅分页和房间示例

You can use Room DAO itself in the RoomDatabase.Callback methods to fill the database. For complete examples see Pagination and Room example

   RoomDatabase.Callback dbCallback = new RoomDatabase.Callback() {
        public void onCreate(SupportSQLiteDatabase db) {
            Executors.newSingleThreadScheduledExecutor().execute(new Runnable() {
                @Override
                public void run() {
                   getYourDB(ctx).yourDAO().insertData(yourDataList);
                }
            });
        }
    };

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