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package org.glassfish.jersey.examples.feedcombiner.provider;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.stream.Collectors;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import org.glassfish.jersey.examples.feedcombiner.model.FeedEntry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.sun.syndication.feed.synd.SyndContent;
import com.sun.syndication.feed.synd.SyndContentImpl;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndEntryImpl;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.feed.synd.SyndFeedImpl;
import com.sun.syndication.io.FeedException;
import com.sun.syndication.io.SyndFeedOutput;
/**
* Provides functionality to convert java object to ATOM representation.
*
* @author Petr Bouda (petr.bouda at oracle.com)
*/
@Provider
@Produces(MediaType.APPLICATION_ATOM_XML)
public class FeedEntriesAtomBodyWriter implements MessageBodyWriter<List<FeedEntry>> {
private static Logger LOG = LoggerFactory.getLogger(FeedEntriesAtomBodyWriter.class.getName());
@Override
public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return MediaType.APPLICATION_ATOM_XML_TYPE.isCompatible(mediaType)
&& Collection.class.isAssignableFrom(type)
&& (((ParameterizedType) genericType).getActualTypeArguments()[0]).equals(FeedEntry.class);
}
@Override
public void writeTo(List<FeedEntry> entries, Class<?> type, Type genericType, Annotation[] annotations,
MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
throws IOException, WebApplicationException {
List<SyndEntry> syndEntries = entries.parallelStream().map(entry -> {
SyndContent description = new SyndContentImpl();
description.setType(MediaType.TEXT_PLAIN);
description.setValue(entry.getDescription());
SyndEntry syndEntry = new SyndEntryImpl();
syndEntry.setTitle(entry.getTitle());
syndEntry.setLink(entry.getLink());
syndEntry.setPublishedDate(entry.getPublishDate());
syndEntry.setDescription(description);
return syndEntry;
}).collect(Collectors.toList());
SyndFeed feed = new SyndFeedImpl();
feed.setFeedType("atom_1.0");
feed.setTitle("Combined Feed");
feed.setDescription("Combined Feed created by a feed-combiner application");
feed.setPublishedDate(new Date());
feed.setEntries(syndEntries);
writeSyndFeed(entityStream, feed);
}
@Override
public long getSize(List<FeedEntry> feeds, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
// deprecated by JAX-RS 2.0 and ignored by Jersey runtime
return 0;
}
private void writeSyndFeed(OutputStream entityStream, SyndFeed feed) {
try {
OutputStreamWriter writer = new OutputStreamWriter(entityStream);
SyndFeedOutput output = new SyndFeedOutput();
output.output(feed, writer);
writer.close();
} catch (FeedException | IOException e) {
LOG.warn("An error occurred during writing a synd feed.", e);
}
}
}