RecyclerView的onBindViewHolder方法为何会重复调用多次？

Question

我正在使用具有GridLayoutManager的RecyclerView。对于网格中的每个项目，我需要调用REST API来检索数据。然后，在从远程异步获取数据之后，我使用UIL来加载/显示图像。

一切似乎都很好。但是我发现对于特定的项目，onBindViewHolder被调用太多太多太多次。

以下是代码示例：

logcat log

言而无信，让我向您展示代码：

@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
    EditCourseImageAttachmentHolder holder = (EditCourseImageAttachmentHolder) viewHolder;
    holder.itemView.setLayoutParams(getLayoutParams(position));
    holder.attachmentView.initData(dataSource.get(headerView == null ? position : position - 1), urlMap);
}
public static class EditCourseImageAttachmentHolder extends RecyclerView.ViewHolder {

    public final AttachmentView attachmentView;

    public EditCourseImageAttachmentHolder(AttachmentView itemView) {
        super(itemView);
        this.attachmentView = itemView;
    }
}

-----------AttachmentView.Java-----------------

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    subscription = tryLoadLocalImage(data)
            .subscribeOn(Schedulers.io())
            .flatMap(new Func1<String, Observable<String>>() {
                @Override
                public Observable<String> call(String localImageUrl) {
                    if (StringUtils.isNotBlank(localImageUrl)) {
                        return Observable.just(localImageUrl);
                    }
                    if (urlMap.containsKey(data.getUid())) {
                        return Observable.just(urlMap.get(data.getUid()));
                    } else {
                        //Remote API call
                        String qiNiuUrl = getQiNiuUrl(data);
                        urlMap.put(data.getUid(), qiNiuUrl);
                        return Observable.just(qiNiuUrl);
                    }
                }
            })
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Action1<String>() {
                @Override
                public void call(String localImageUrl) {
                    showImage(localImageUrl);
                }
            }, new Action1<Throwable>() {
                @Override
                public void call(Throwable throwable) {
                }
            });
}

@Override
protected void onDetachedFromWindow() {
    super.onDetachedFromWindow();
    if (subscription != null && subscription.isUnsubscribed()) {
        subscription.unsubscribe();
    }
}

- Victor Liang

Answer 1

根本原因是我更改了ItemView的LayoutParam....

在我删除这些代码之后，它可以正常工作。 但是，很奇怪的是只有特定位置的项目会重新绑定。

- Victor Liang

Answer 2

if (subscription != null && !subscription.isUnsubscribed()) {
    subscription.unsubscribe();
}

你的代码应该是这样的...

- Jclick