实时抓取标记的 Instagram 照片

Question

我正在尝试实时下载带有特定标签的照片。我发现实时 api 非常无用，所以我使用长轮询策略。下面是伪代码，其中包含一些微妙的错误。

newMediaCount = getMediaCount();
delta = newMediaCount - mediaCount;
if (delta > 0) {
    // if mediaCount changed by now, realDelta > delta, so realDelta - delta photos won't be grabbed and on next poll if mediaCount didn't change again realDelta - delta would be duplicated else ...
    // if photo posted from private account last photo will be duplicated as counter changes but nothing is added to recent
    recentMedia = getRecentMedia(delta);
    // persist recentMedia
    mediaCount = newMediaCount;
}

第二个问题可以用我猜的某种集合来解决。但首先真的很困扰我。我已将两个调用移至尽可能近的 instagram api，但这是否足够？

编辑

正如 Amir 建议的那样，我使用 min/max_tag_ids 重写了代码。但它仍然会跳过照片。我找不到比将图像保存在磁盘上一段时间并将结果与​​instagram.com/explore/tags/ 进行比较更好的测试方法。

public class LousyInstagramApiTest {

   @Test
    public void testFeedContinuity() throws Exception {
        Instagram instagram = new Instagram(Settings.getClientId());
        final String TAG_NAME = "portrait";
        String id = instagram.getRecentMediaTags(TAG_NAME).getPagination().getMinTagId();
        HashtagEndpoint endpoint = new HashtagEndpoint(instagram, TAG_NAME, id);

        for (int i = 0; i < 10; i++) {
            Thread.sleep(3000);
            endpoint.recentFeed().forEach(d -> {
                try {
                    URL url = new URL(d.getImages().getLowResolution().getImageUrl());
                    BufferedImage img = ImageIO.read(url);
                    ImageIO.write(img, "png", new File("D:\\tmp\\" + d.getId() + ".png"));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            });
        }
    }
}

class HashtagEndpoint {
    private final Instagram instagram;
    private final String hashtag;
    private String minTagId;

    public HashtagEndpoint(Instagram instagram, String hashtag, String minTagId) {
        this.instagram = instagram;
        this.hashtag = hashtag;
        this.minTagId = minTagId;
    }

    public List<MediaFeedData> recentFeed() throws InstagramException {
        TagMediaFeed feed = instagram.getRecentMediaTags(hashtag, minTagId, null);
        List<MediaFeedData> dataList = feed.getData();
        if (dataList.size() == 0) return Collections.emptyList();

        String maxTagId = feed.getPagination().getNextMaxTagId();
        if (maxTagId != null && maxTagId.compareTo(minTagId) > 0) dataList.addAll(paginateFeed(maxTagId));
        Collections.reverse(dataList);
//        dataList.removeIf(d -> d.getId().compareTo(minTagId) < 0);

        minTagId = feed.getPagination().getMinTagId();
        return dataList;
    }

    private Collection<? extends MediaFeedData> paginateFeed(String maxTagId) throws InstagramException {
        System.out.println("pagination required");

        List<MediaFeedData> dataList = new ArrayList<>();
        do {
            TagMediaFeed feed = instagram.getRecentMediaTags(hashtag, null, maxTagId);
            maxTagId = feed.getPagination().getNextMaxTagId();
            dataList.addAll(feed.getData());
        } while (maxTagId.compareTo(minTagId) > 0);
        return dataList;
    }

}

Answer 1

使用Tag endpoints 获取带有所需标签的最近媒体，它会在其分页信息中返回min_tag_id，该信息与您调用时最近标记的媒体相关联。由于 API 还接受 min_tag_id 参数，因此您可以从上次查询中传递该数字，以便仅接收在您上次查询之后标记的那些媒体。

因此，根据您拥有的任何轮询机制，您只需调用 API 即可根据上次收到的min_tag_id 获取最新的媒体（如果有）。

您还需要传递一个大的count 参数并按照响应的分页来接收所有数据而不会在标记速度快于轮询速度时丢失任何数据。

更新：
根据您更新的代码：

public List<MediaFeedData> recentFeed() throws InstagramException {
    TagMediaFeed feed = instagram.getRecentMediaTags(hashtag, minTagId, null, 100000);
    List<MediaFeedData> dataList = feed.getData();
    if (dataList.size() == 0) return Collections.emptyList();

    // follow the pagination
    MediaFeed recentMediaNextPage = instagram.getRecentMediaNextPage(feed.getPagination());
    while (recentMediaNextPage.getPagination() != null) {
        dataList.addAll(recentMediaNextPage.getData());
        recentMediaNextPage = instagram.getRecentMediaNextPage(recentMediaNextPage.getPagination());
    }

    Collections.reverse(dataList);

    minTagId = feed.getPagination().getMinTagId();
    return dataList;
}