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package org.glassfish.jersey.examples.feedcombiner.manager;
import java.net.URL;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Collectors;
import org.glassfish.jersey.examples.feedcombiner.model.CombinedFeed;
import org.glassfish.jersey.examples.feedcombiner.model.FeedEntry;
import org.glassfish.jersey.examples.feedcombiner.store.InMemoryDataStore;
import org.slf4j.LoggerFactory;
import static org.glassfish.jersey.examples.feedcombiner.model.CombinedFeed.CombinedFeedBuilder.of;
import com.sun.syndication.feed.synd.SyndEntry;
/**
* An instance of this class implements the {@link Runnable#run() run method}
* with functionality of downloading all entries from feed which are available.
* These entries are added into the combined feed and stored in the database again
* (storing means rewrite previous combined feed by a new version with added entries).
*
* @author Petr Bouda (petr.bouda at oracle.com)
*/
public class FeedDownloadTask implements Runnable {
private static org.slf4j.Logger LOG = LoggerFactory.getLogger(FeedDownloadTask.class.getName());
private final FeedEntryMapper entryMapper = new FeedEntryMapper();
private final Function<URL, List<SyndEntry>> feedDownloader;
private final InMemoryDataStore datastore;
private final String combinedFeedID;
FeedDownloadTask(Function<URL, List<SyndEntry>> feedDownloader, InMemoryDataStore datastore, String feedId) {
this.combinedFeedID = feedId;
this.datastore = datastore;
this.feedDownloader = feedDownloader;
}
@Override
public void run() {
CombinedFeed fetchedCombinedFeed = datastore.get(combinedFeedID, CombinedFeed.class);
if (fetchedCombinedFeed == null) {
LOG.warn("There is no CombinedFeed for the ID: " + combinedFeedID);
return;
}
List<FeedEntry> entries = fetchedCombinedFeed.getUrls().stream()
.map(feedDownloader)
.flatMap(Collection::stream)
.map(entryMapper)
.filter(Objects::nonNull)
.sorted((e1, e2) -> e2.getPublishDate().compareTo(e1.getPublishDate()))
.collect(Collectors.toList());
CombinedFeed combinedFeed = of(fetchedCombinedFeed).feedEntries(entries).build();
datastore.put(combinedFeedID, combinedFeed);
LOG.debug("New entries for the CombinedFeed were downloaded [combined-feed={}, entries-count={}]",
combinedFeed.getId(), entries.size());
}
/**
* The mapper which is used for transform {@link SyndEntry synd entry} to
* this application-friendly version {@link FeedEntry feed entry}.
*
* @author Petr Bouda (petr.bouda at oracle.com)
**/
private static class FeedEntryMapper implements Function<SyndEntry, FeedEntry> {
@Override
public FeedEntry apply(SyndEntry entry) {
if (entry.getDescription() == null) {
return null;
}
String title = entry.getTitle();
String link = entry.getLink();
String description = entry.getDescription().getValue();
Date publishedDate = entry.getPublishedDate();
return new FeedEntry(title, link, description, publishedDate);
}
}
}