使用RxJava在不同的线程上进行领域，网络操作，订阅和观察 [英] Realm, network operations, subscribing and observing on different threads with RxJava

问题描述

我需要:

• 在后台线程上从API获取一些数据
• 在用户界面上显示数据

• 保存到领域.

• Fetch some data from an API on a background thread
• Display the data on the UI

• Save to Realm.

fetchItemsFromServer().subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread()).subscribe(new Action1<ItemList>() {
    @Override
    public void call(ItemList items) {

        displayItems(items);

        try {
            realm.beginTransaction();
            realm.copyToRealmOrUpdate(itemList);
            realm.commitTransaction();
            Logger.v("Realm ", "Copied list object to realm");
        } catch (Exception e) {
            Logger.e("Realm Something went wrong ", e);
            realm.cancelTransaction();
        }

    }
}

这将引发错误: 从错误的线程访问的领域

This throws an error : realm accessed from incorrect thread

我有4个标签可同时提取不同的消息.

I have 4 tabs fetching different messages at the same time.

fetchItemsFromServer()是一个密集的调用，并且将此调用限制在一个线程中是不好的.我需要这种灵活性.

fetchItemsFromServer() is an intensive call and confining this call to one thread is not good. I need this flexibility.

有人用这种方式使用领域找到任何解决方法吗?

Has anyone found any workarounds using realm this way?

大多数示例都倾向于将重点放在从Realm获取与使用网络操作上:

Most examples e.g tend to be focused on fetching from Realm vs working with network operations:

以下示例:

Rxjava- https://realm.io/news/realm-java-0.87 .0/

在RxJava中使用领域- https://realm.io/news/using- realm-with-rxjava/(以前的解决方案，但性能方面有缺陷)

Using realm with RxJava - https://realm.io/news/using-realm-with-rxjava/ (previous solution but performance drawbacks)

My Realm由数据库模块通过依赖项注入(Dagger 2)提供

My Realm is provided by a database module through dependency injection (Dagger 2)

@Module
public class DatabaseModule {

    public static final String REALM_FILE_NAME = "Realm name";

    @Provides
    Realm providesRealmInstance(Context context) {
    return Realm.getInstance(
            new RealmConfiguration.Builder(context)
                    .name(REALM_FILE_NAME)
                    .build());
    }
}

推荐答案

不是在UI线程上保存数据，而是在后台使用以下模式进行操作:

Instead of saving data on the UI thread I would do it on the background instead using the following pattern:

fetchItemsFromServer()
    .doOnNext(new Action1<ItemList>() {
        @Override
        public ItemList call(ItemList list) {
            // Save data on the background thread
            Realm realm = Realm.getDefaultInstance();
            realm.beginTransaction();
            realm.copyToRealmOrUpdate(list);
            realm.commitTransaction();
            realm.close();
        }
    })
  .subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread())
  .subscribe(new Action1<ItemList>() {
    @Override
    public void call(ItemList items) {
        displayItems(items);
    }
}

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