android - RxJava 与 SQlite 和 ContentProvider 操作

Question

我正在研究 RxJava，为此我正在使用 SQLite，编写一个辅助类 SQLiteUtils 以帮助更轻松地处理异步 ContentResolver 查询。例如，这是 queryInBackground 方法:

static
public <T> Observable<T> queryInBackground(
        final ContentResolver cr,
        final Uri uri,
        final String[] projection,
        final String selection,
        final String[] selectionArgs,
        final String sortOrder,
        final CursorHandler<T> ch) {
    return  Observable.create(new Observable.OnSubscribe<T>() {
        @Override
        public void call(Subscriber<? super T> observer) {
            if (!observer.isUnsubscribed()) {
                Cursor cursor = null;
                try {
                    cursor = cr.query(uri, projection, selection, selectionArgs, sortOrder);
                    if (cursor != null && cursor.getCount() > 0) {
                        while (cursor.moveToNext()) {
                            observer.onNext(ch.handle(cursor));
                        }
                    }
                    observer.onCompleted();
                } catch (Exception err) {
                    observer.onError(err);

                } finally {
                    if (cursor != null) cursor.close();
                }
            }
        }
    }).subscribeOn(Schedulers.computation());
}

其中 CursorHandler 是一个接口(interface):

/**
 * Implementations of this interface convert Cursor into other objects.
 *
 * @param <T> the target type the input Cursor will be converted to.
 */
public interface CursorHandler<T> {
    T handle(Cursor cu) throws SQLException;
}

我已经阅读了有关 Schedulers 的文档，但我不太确定 Schedulers.computation() 是否是正确的选择。

如果我想为基本的 HttpUrlConnection 操作实现一些类似的东西，我应该选择哪个 Scheduler？ Schedulers.newThread() 或 Schedulers.io()，我会坚持使用 Schedulers.io() ...但不确定。

提前致谢。

祝一切顺利，卢卡

Answer 1

根据 this answer你应该使用 Schedulers.io()。相关引用:

io() is backed by an unbounded thread-pool and is the sort of thing you'd use for non-computationally intensive tasks, that is stuff that doesn't put much load on the CPU. So yep interaction with the file system, interaction with databases or services on a different host are good examples.