如何将 Room Persistence Library 与预先填充的数据库一起使用? [英] How to use Room Persistence Library with pre-populated database?

问题描述

我想将 Room 与预先填充的数据库一起使用，但我不明白如何告诉 Room 在哪里可以找到我的数据库.

I'd like to use Room with a pre-populated database, but I can't understand how to tell Room where to find my database.

我现在把它放在 src/main/assets/databases 中，当我为 Room 数据库创建实例时，我是这样创建的:

I've now put it in src/main/assets/databases and when I create the instance for the Room database I create it this way:

Room.databaseBuilder(
    getApplicationContext(),
    AppDatabase.class,
    "justintrain.db"
)
.allowMainThreadQueries()
.build();

这样，我认为它每次都会创建一个新数据库，或者无论如何，它没有使用预先填充的数据库.

This way tho, I think it's creating a new database every time, or anyways, it's not using the pre-populated one.

如何让它找到我的数据库?

How can I make it to find my database?

推荐答案

这就是我解决的方法，以及如何使用预填充的数据库(最高 Room v. alpha5)发布应用程序

This is how I solved it, and how you can ship your application with a pre-populated database (up to Room v. alpha5)

• 将您的 SQLite DB database_name.db 放入 assets/databases 文件夹

从这个 repo 中取出文件 并将它们放入一个名为 的包中sqlAsset

take the files from this repo and put them in a package called i.e. sqlAsset

在您的 AppDatabase 类中，相应地修改 Room 的数据库创建代码:

in your AppDatabase class, modify your Room's DB creation code accordingly:

Room.databaseBuilder(context.getApplicationContext(), 
                     AppDatabase.class, 
                     "database_name.db")
.openHelperFactory(new AssetSQLiteOpenHelperFactory())
.allowMainThreadQueries()
.build();

请注意，您必须使用 "database_name.db" 而不是 getDatabasePath() 或其他方法:它只需要文件名.

Note that you have to use "database_name.db" and not getDatabasePath() or other methods: it just needs the name of the file.

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