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。下面是带有 sublte 错误注释的伪代码

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;
}

我想第二个问题可以用某种 Set 来解决。但首先真的让我很困扰。我已将两次对 instagram api 的调用移动到尽可能接近的位置，但这就足够了吗？

编辑

正如 Amir 所建议的那样，我已经使用 min/max_tag_id 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;
    }

}

最佳答案

使用 Tag endpoints要获取带有所需标签的最近媒体，它会在其分页信息中返回一个 min_tag_id，该信息与您调用时最近标记的媒体相关联。由于该 API 还接受 min_tag_id 参数，您可以从上次查询中传递该数字，以仅接收在上次查询后标记的媒体。

因此，基于您拥有的任何轮询机制，您只需调用 API 以根据最后收到的 min_tag_id 获取最近的新媒体(如果有的话)。

您还需要传递一个大的 count 参数并遵循响应的分页以在标记速度快于轮询时接收所有数据而不会丢失任何内容。

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;
}

关于java - 实时抓取标记的 instagram 照片，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29870679/