Twitter数据抓取的方法(三)

Scraping Tweets Directly from Twitters Search – Update

Published August 1, 2015

Sorry for my delayed response to this as I’ve seen several comments on this topic, but I’ve been pretty busy with some other stuff recently, and this is the first chance I’ve had to address this!

As with most web scraping, at some point a provider will change their source code and scrapers will break. This is something that Twitter has done with their recent site redesign. Having gone over the changes, there are two that effect this scraping script.

The first change is tiny. Originally, to get all tweets rather than “top tweet”, we used the type_param “f” to denote “realtime”. However, the value for this has changed to just “tweets”.

Second change is a bit trickier to counter, as the scroll_cursor parameter no longer exists. Instead, if we look at the AJAX call that Twitter makes on its infinite scroll, we get a different parameter:

max_position:TWEET-399159003478908931-606844263347945472-BD1UO2FFu9QAAAAAAAAETAAAAAcAAAASAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

The highlighted parameter there, “max_position”, looks very similar to the original scroll_cursor parameter. However, unlike the scroll_cursor which existed in the response to be extracted, we have to create this one ourself.

As can be seen from the example, we have “TWEET” followed by two sets of numbers, and what appears to be “BD1UO2FFu9” screaming and falling off a cliff. The good news is, we actually only need the first three components.

“TWEET” will always stay the same, but the two sets of numbers are actually tweet ID’s, representing the oldest to most recently created tweets you’ve extracted.

For our newest tweet (2nd number set), we only need to extract this once as we can keep it the same for all calls, as Twitter does.

The oldest tweet (1st number set), we need to extract the last tweet id in our results each time to change our max_position value.

So, lets take a look at some of the code I’ve changed:

String minTweet = null;
while((response = executeSearch(url))!=null && continueSearch && !response.getTweets().isEmpty()) {
    if(minTweet==null) {
        minTweet = response.getTweets().get(0).getId();
    }
    continueSearch = saveTweets(response.getTweets());
    String maxTweet = response.getTweets().get(response.getTweets().size()-1).getId();
    if(!minTweet.equals(maxTweet)) {
        try {
            Thread.sleep(rateDelay);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String maxPosition = "TWEET-" + maxTweet + "-" + minTweet;
        url = constructURL(query, maxPosition);
    }
}
 
...
 
public final static String TYPE_PARAM = "f";
public final static String QUERY_PARAM = "q";
public final static String SCROLL_CURSOR_PARAM = "max_position";
public final static String TWITTER_SEARCH_URL = "https://twitter.com/i/search/timeline";
 
public static URL constructURL(final String query, final String maxPosition) throws InvalidQueryException {
    if(query==null || query.isEmpty()) {
        throw new InvalidQueryException(query);
    }
    try {
        URIBuilder uriBuilder;
        uriBuilder = new URIBuilder(TWITTER_SEARCH_URL);
        uriBuilder.addParameter(QUERY_PARAM, query);
        uriBuilder.addParameter(TYPE_PARAM, "tweets");
        if (maxPosition != null) {
            uriBuilder.addParameter(SCROLL_CURSOR_PARAM, maxPosition);
        }
        return uriBuilder.build().toURL();
    } catch(MalformedURLException | URISyntaxException e) {
        e.printStackTrace();
        throw new InvalidQueryException(query);
    }
}

Rather than our original scroll_cursor value, we now have “minTweet”. Initially this is set to null, as we don’t have one to begin with. On our first call though, we get the first tweet in our response, and set the ID to minTweet, if minTweet is still null.

Next, we need to get the maxTweet. As previously said before, we get this by getting the last tweet in our results, and returning that ID. So we don’t repeat results, we need to make sure that the minTweet does not equal the maxTweet ID, and if not, we construct our “max_position” query with the format “TWEET-{maxTweetId}-{minTweetId}”.

You’ll also notice I changed the SCROLL_CURSOR_PARAM to “max_position” from “scroll_cursor”. Normally I’d change the variable name as well, but for visual reference, I’ve kept it the same for now, so you know where to change it.

Also, in constructUrl, the TYPE_PARAM value has also been set to “tweets”.

Finally, make sure you modify your TwitterResponse class so that it mirrors the parameters that are returned by the JSON file.

All you need to do is replace the original class variables with these, and update the constructor and getter/setter fields:

private boolean has_more_items;
private String items_html;
private String min_position;
private String refresh_cursor;
private long focused_refresh_interval;