Question

我正在尝试下载实时发布的带有特定标签的照片。我发现实时api很无用，所以我使用长轮询策略。下面是伪代码，其中包含sublte bug的注释

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;
}

第二个问题可以通过Set of some sort来解决。但首先真的困扰我。我已尽可能接近两次打电话给instagram api，但这还够吗？

修改

正如Amir建议我使用min/max_tag_id s重写了代码。但它仍然会跳过照片。我找不到更好的方法来测试这个，而不是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。

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获取具有所需标记的最近媒体，它会在其分页信息中返回min_tag_id，该信息与您通话时最近标记的媒体相关联。由于API还接受min_tag_id参数，因此您可以将上次查询中的该号码传递给仅接收上次查询后标记的媒体。

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获取新的最新媒体。

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时丢失任何内容。

<强>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;
}

实时抓取标记的Instagram照片

1 个答案: