Spring Integration: how to read multiple RSS channels? - rss

Question

I wrote my app that reads RSS feed. It works super with one channel which I have in beans.xml like this:
<feed:inbound-channel-adapter id="news"
channel="inputRssFeedChannel"
url="http://feeds.feedburner.com/Techcrunch">
<int:poller fixed-rate="5000" max-messages-per-poll="100"/>
</feed:inbound-channel-adapter>
<int:service-activator input-channel="inputRssFeedChannel"
ref="rssPrintOutService"
method="printRss"
output-channel="nullChannel"/>
Every time it just calls RssHandler which deal with SyndEntry. But what should I do if I'd like to read few rss urls (2,5,20 or etc...)?

Answer 1

Create your own implementation of org.springframework.integration.core.MessageSource and use it in input-channel reference like the following:
<int:inbound-channel-adapter id="newsInput" ref="newsReader">
<int:poller fixed-rate="1" time-unit="SECONDS" max-messages-per-poll="1"/>
</int:inbound-channel-adapter>
<bean id="newsReader" class="blog.NewsReader">
<property name="fetcherListener">
<bean class="blog.helper.FetcherEventListenerImpl"/>
</property>
<property name="urls">
<list>
<value>http://www.gridshore.nl/feed/</value>
<value>https://spring.io/blog.atom</value>
<value>http://feeds.foxnews.com/foxnews/video?format=xml</value>
</list>
</property>
</bean>
The class NewsReader uses list mentioned in urls propriety and retrieve the feed.
Please refer to the receive method below.
public class NewsReader implements MessageSource, InitializingBean {
private static Logger logger = LoggerFactory.getLogger(NewsReader.class);
private FeedFetcherCache feedInfoCache;
private FeedFetcher feedFetcher;
private FetcherListener fetcherListener;
private List<String> urls;
#Override
public Message receive() {
List<SyndFeed> feeds = obtainFeedItems();
return MessageBuilder.withPayload(feeds)
.setHeader("feedid", "newsfeed").build();
}
private List<SyndFeed> obtainFeedItems() {
List<SyndFeed> feed = new ArrayList<>();
try {
for (String url : urls) {
feed.add(feedFetcher.retrieveFeed(new URL(url)));
}
} catch (IOException e) {
logger.error("IO Problem while retrieving feed", e);
} catch (FeedException e) {
logger.error("Feed Problem while retrieving feed", e);
} catch (FetcherException e) {
logger.error("Fetcher Problem while retrieving feed", e);
}
return feed;
}
#Override
public void afterPropertiesSet() throws Exception {
feedInfoCache = HashMapFeedInfoCache.getInstance();
feedFetcher = new HttpURLFeedFetcher(feedInfoCache);
if (fetcherListener != null) {
feedFetcher.addFetcherEventListener(fetcherListener);
}
}
public void setFetcherListener(FetcherListener fetcherListener) {
this.fetcherListener = fetcherListener;
}
public void setUrls(List<String> urls) {
this.urls = urls;
}
In case you want to take a look of my complete code:
git clone https://github.com/BikashShaw/MultipleRSSFeedRead.git