捆绑 Realm 文件 - Java SDK

Overview

要创建 Realm 文件并将其与应用程序捆绑在一起，请执行以下操作：

1. 创建一个 Realm 文件，其中包含要捆绑的数据。

2. 将 Realm 文件捆绑到生产应用程序的/<app name>/src/main/assets文件夹中。

3. 在生产应用程序中，从捆绑的资产文件中打开 Realm 。 对于同步 Realm，您必须提供分区键。

创建用于捆绑的 Realm 文件

1. 构建一个共享应用程序数据模型的临时 Realm 应用。

2. 打开一个 Realm 并添加要捆绑的数据。 如果使用同步 Realm，请留出时间让 Realm 完全同步。

3. 使用writeCopyTo()方法将 Realm 复制到新文件中：

   Java

   Kotlin

   String appID = YOUR_APP_ID; // replace this with your App ID
   App app = new App(appID);
   Credentials anonymousCredentials = Credentials.anonymous();
   app.loginAsync(anonymousCredentials, it -> {
       if (it.isSuccess()) {
           Log.v("EXAMPLE", "Successfully authenticated anonymously.");
           String PARTITION = "PARTITION_YOU_WANT_TO_BUNDLE";
           // you can only create realm copies on a background thread with a looper.
           // HandlerThread provides a Looper-equipped thread.
           HandlerThread handlerThread = new HandlerThread("CopyARealmHandler");
           handlerThread.start();
           Handler handler = new Handler(handlerThread.getLooper());
           handler.post(new Thread(new Runnable() { @Override public void run() {
               SyncConfiguration config = new SyncConfiguration.Builder(app.currentUser(), PARTITION)
                       // wait for the realm to download all data from the backend before opening
                       .waitForInitialRemoteData()
                       .build();
               Realm realm = Realm.getInstance(config);
               Log.v("EXAMPLE", "Successfully opened a realm.");
               // write a copy of the realm you can manually copy to your production application assets
               File outputDir = activity.getApplicationContext().getCacheDir();
               File outputFile = new File(outputDir.getPath() + "/" +  PARTITION + "_bundled.realm");
               // ensure all local changes have synced to the backend
               try {
                   app.getSync().getSession(config).uploadAllLocalChanges(10000, TimeUnit.MILLISECONDS);
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }
               // cannot write to file if it already exists. Delete the file if already there
               outputFile.delete();
               realm.writeCopyTo(outputFile);
               // search for this log line to find the location of the realm copy
               Log.i("EXAMPLE", "Wrote copy of realm to " + outputFile.getAbsolutePath());
               // always close a realm when you're done using it
               realm.close();
           }}));
       } else {
           Log.e("EXAMPLE", "Failed to authenticate: " + it.getError().toString());
       }
   });

   val appID: String = YOUR_APP_ID // replace this with your App ID
   val app = App(appID)
   val anonymousCredentials = Credentials.anonymous()
   app.loginAsync(anonymousCredentials) { it: App.Result<User?> ->
       if (it.isSuccess) {
           Log.v("EXAMPLE", "Successfully authenticated anonymously.")
           val PARTITION = "PARTITION_YOU_WANT_TO_BUNDLE"
           // you can only create realm copies on a background thread with a looper.
           // HandlerThread provides a Looper-equipped thread.
           val handlerThread = HandlerThread("CopyARealmHandler")
           handlerThread.start()
           val handler = Handler(handlerThread.looper)
           handler.post(Thread {
               val config = SyncConfiguration.Builder(app.currentUser(), PARTITION)
                   // wait for the realm to download all data from the backend before opening
                   .waitForInitialRemoteData()
                   .build()
               val realm : Realm = Realm.getInstance(config);
               Log.v("EXAMPLE", "Successfully opened a realm.")
               // write a copy of the realm you can manually copy to your production application assets
               val outputDir = activity!!.applicationContext.cacheDir
               val outputFile =
                   File(outputDir.path + "/" + PARTITION + "_bundled.realm")
               // ensure all local changes have synced to the backend
               try {
                   app.sync.getSession(config)
                       .uploadAllLocalChanges(10000, TimeUnit.MILLISECONDS)
               } catch (e: InterruptedException) {
                   e.printStackTrace()
               }
               // cannot write to file if it already exists. Delete the file if already there
               outputFile.delete()
               realm.writeCopyTo(outputFile)
               // search for this log line to find the location of the realm copy
               Log.i("EXAMPLE", "Wrote copy of realm to " + outputFile.absolutePath)
               // always close a realm when you're done using it
               realm.close()
           })
       } else {
           Log.e("EXAMPLE", "Failed to authenticate: ${it.error}")
       }
   }

   writeCopyTo() 在复制之前会自动将您的 Realm 压缩到尽可能小的大小。

   提示

   同步 Realm 和仅限本地 Realm 之间的区别

   上述示例使用SyncConfiguration来配置同步 Realm。 要创建本地 Realm 的副本，请改为使用RealmConfiguration配置您的 Realm。

在生产应用程序中捆绑 Realm 文件

现在您已拥有包含初始数据的 Realm 副本，请将其与生产应用程序捆绑在一起。

1. 搜索应用程序日志，找到刚刚创建的 Realm 文件副本的位置。

2. 使用 Android Studio 窗口右下角的“设备文件浏览器”小部件，导航到该文件。

3. 右键单击该文件并选择“另存为”。 导航到生产应用程序的/<app name>/src/main/assets文件夹。 在此处保存 Realm 文件的副本。

从捆绑的 Realm 文件中打开 Realm

现在您已拥有生产应用程序中包含的域副本，您需要添加代码来使用它。 配置域以从捆绑文件中打开域时，请使用assetFile()方法：

String appID = YOUR_APP_ID; // replace this with your App ID
App app = new App(appID);
Credentials anonymousCredentials = Credentials.anonymous();
app.loginAsync(anonymousCredentials, it -> {
    if (it.isSuccess()) {
        Log.v("EXAMPLE", "Successfully authenticated anonymously.");
        // asset file name should correspond to the name of the bundled file
        SyncConfiguration config = new SyncConfiguration.Builder(
                    app.currentUser(),
                    "PARTITION_YOU_WANT_TO_BUNDLE")
                .assetFile("example_bundled.realm")
                .build();
        Realm realm = Realm.getInstance(config);
        Log.v("EXAMPLE", "Successfully opened bundled realm.");
        // read and write to the bundled realm as normal
        realm.executeTransactionAsync(transactionRealm -> {
            Frog frog = new Frog(new ObjectId(),
                    "Asimov",
                    4,
                    "red eyed tree frog",
                    "Spike");
            transactionRealm.insert(frog);
            expectation.fulfill();
        });
    } else {
        Log.e("EXAMPLE", "Failed to authenticate: " + it.getError().toString());
    }
});

val appID: String = YOUR_APP_ID // replace this with your App ID
val app = App(appID)
val anonymousCredentials = Credentials.anonymous()
app.loginAsync(anonymousCredentials) { it: App.Result<User?> ->
    if (it.isSuccess) {
        Log.v("EXAMPLE", "Successfully authenticated anonymously.")
        // asset file name should correspond to the name of the bundled file
        val config = SyncConfiguration.Builder(
                app.currentUser(),
                "PARTITION_YOU_WANT_TO_BUNDLE")
            .assetFile("example_bundled.realm")
            .build()
        val realm: Realm = Realm.getInstance(config)
        Log.v("EXAMPLE", "Successfully opened bundled realm.")
        // read and write to the bundled realm as normal
        realm.executeTransactionAsync { transactionRealm: Realm ->
            val frog = Frog(
                ObjectId(),
                "Asimov",
                4,
                "red eyed tree frog",
                "Spike"
            )
            transactionRealm.insert(frog)
            expectation.fulfill()
        }
    } else {
        Log.e("EXAMPLE", "Failed to authenticate: ${it.error}")
    }
}