android - 如何在整个应用程序生命周期中维护单个 Realm 实例并关闭它？

Question

如何在应用程序的整个生命周期中维护单个 Realm 实例并关闭它。

我可以使用单例类来维护实例，但是当应用程序关闭时我该如何关闭它？

此外，Realm 实例一旦打开就不要关闭是否安全？

Answer 1

我倾向于使用单例 RealmManager 对于 UI 线程，对于后台线程，我使用 try-with-sources 打开/关闭 Realm block 。

所以对于 UI 线程:

public class RealmManager {
    private static final String TAG = "RealmManager";

    static Realm realm;

    static RealmConfiguration realmConfiguration;

    public static void initializeRealmConfig(Context appContext) {
        if(realmConfiguration == null) {
            Log.d(TAG, "Initializing Realm configuration.");
            setRealmConfiguration(new RealmConfiguration.Builder(appContext).initialData(new RealmInitialData())
                    .deleteRealmIfMigrationNeeded()
                    .inMemory()
                    .build());
        }
    }

    public static void setRealmConfiguration(RealmConfiguration realmConfiguration) {
        RealmManager.realmConfiguration = realmConfiguration;
        Realm.setDefaultConfiguration(realmConfiguration);
    }

    private static int activityCount = 0;

    public static Realm getRealm() {
        return realm;
    }

    public static void incrementCount() {
        if(activityCount == 0) {
            if(realm != null) {
                if(!realm.isClosed()) {
                    Log.w(TAG, "Unexpected open Realm found.");
                    realm.close();
                }
            }
            Log.d(TAG, "Incrementing Activity Count [0]: opening Realm.");
            realm = Realm.getDefaultInstance();
        }
        activityCount++;
        Log.d(TAG, "Increment: Count [" + activityCount + "]");
    }

    public static void decrementCount() {
        activityCount--;
        Log.d(TAG, "Decrement: Count [" + activityCount + "]");
        if(activityCount <= 0) {
            Log.d(TAG, "Decrementing Activity Count: closing Realm.");
            activityCount = 0;
            realm.close();
            if(Realm.compactRealm(realmConfiguration)) {
                Log.d(TAG, "Realm compacted successfully.");
            }
            realm = null;
        }
    }
}

对于后台线程:

try(Realm realm = Realm.getDefaultInstance()) {
   // ...
}