运行带有.realm文件的Android应用程序，并将其用作默认数据库 [英] shipping Android app with a .realm file and use it as a default database

问题描述

我在 assets / default.realm 文件夹中有一个default.realm文件，我无法将其设为默认领域数据库

i have a default.realm file in my "assets/default.realm" folder, I am not able to make it as a default realm database

realm.getDefaultInstance();
        src= new File("assets/default.realm");
        dst=new File("/data/data/" + context.getPackageName() + "/files/");
        if (!(realm.isEmpty())) {
            Log.v("DB","already there!!");
        } else {
            try {
                copyFile(src,dst);
            } catch (IOException e) {
                Log.v("DB","Wrong Path!");
            }
        }
void copyFile(File src, File dst) throws IOException {
        FileChannel inChannel = new FileInputStream(src).getChannel();
        FileChannel outChannel = new FileOutputStream(dst).getChannel();
        try {
            inChannel.transferTo(0, inChannel.size(), outChannel);
        } finally {
            if (inChannel != null)
                inChannel.close();
            if (outChannel != null)
                outChannel.close();
        }
    }

但无法复制请帮助

推荐答案

而不是手动复制Realm文件，您可以将其添加到 RealmConfiguration ：< a href =https://realm.io/docs/java/1.1.1/api/io/realm/RealmConfiguration.Builder.html#assetFile-android.content.Context-java.lang.String- = nofollow> https://realm.io/docs/java/1.1.1/api/io/realm/RealmConfiguration.Builder.html#assetFile-android.content.Context-java.lang.String-

Instead of manually copy the Realm file, you can add it to your RealmConfiguration: https://realm.io/docs/java/1.1.1/api/io/realm/RealmConfiguration.Builder.html#assetFile-android.content.Context-java.lang.String-

您的Realm文件可能与您的类不同，并且会抛出 MigrationIsNeeded 异常。在这种情况下，您必须编写迁移步骤： https://realm.io/docs / java / latest /＃migrations

Your Realm file might differ from your classes, and MigrationIsNeeded exception will be thrown. In that case, you will have to write a migration step: https://realm.io/docs/java/latest/#migrations

所以你最终会得到类似的结果：

So you will end up with something like:

RealmMigration migration = new RealmMigration() {
    @Override
    public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
        RealmSchema schema = realm.getSchema();
        if (oldVersion == 0) {
            schema.create("Person")
                .addField("name", String.class)
                .addField("age", int.class);
            oldVersion++;
        }
    }
};

RealmConfiguration config = new RealmConfiguration.B‌​uilder(this)
  .name(Realm.DEFAULT_‌​REALM_NAME)
  .migration(migration)
  .assetFile(this,"Def‌​ault.realm")
  .schemaVersion(1)
  .build(); 

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