Feed interface provides ‘getEntry’ method, it return the entry by id.
Entry getEntry(String id)
Retrieves the first entry in the feed with the given id value.
Feedutil.java
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Optional;
import java.util.zip.GZIPInputStream;
import org.apache.abdera.Abdera;
import org.apache.abdera.model.Document;
import org.apache.abdera.model.Feed;
import org.apache.abdera.parser.Parser;
/**
* Utility class to parse Atom feed.
*
* Usage :
*
*Instantiate FeedUtil with atom document url. Call the getFeed method
*to get the feed document associated with url.
*
*
* @author Hari Krishna Gurram
*
*/
public class FeedUtil {
private String url;
private InputStream in = null;
private Feed feed = null;
HttpURLConnection conn = null;
public FeedUtil(String url) {
this.url = url;
}
/**
*
* @param url
* @return Optional.empty if url is null (or) unable to parse the url, else
* return the Document object.
*/
private OptionalDocumentFeed>> getDocument() {
if (url == null) {
return Optional.empty();
}
try {
URL urlTemp = new URL(url);
conn = (HttpURLConnection) urlTemp.openConnection();
conn.setRequestProperty("Accept-Encoding", "gzip");
conn.connect();
String contentEncoding = conn.getContentEncoding();
boolean isGzip = contentEncoding != null && contentEncoding.contains("gzip");
in = !isGzip ? conn.getInputStream() : new GZIPInputStream(conn.getInputStream());
Abdera abdera = Abdera.getInstance();
Parser parser = abdera.getParser();
DocumentFeed> document = parser.parse(in, url.toString());
return Optional.of(document);
} catch (Exception e) {
e.printStackTrace();
}
return Optional.empty();
}
/**
*
* @return the Feed object associated with given {@link url}. In any case if
* the feed creation is failed, then it return Optional.empty().
*/
public synchronized OptionalFeed> getFeed() {
if (feed != null) {
return Optional.of(feed);
}
OptionalDocumentFeed>> documentOpt = getDocument();
if (!documentOpt.isPresent()) {
return Optional.empty();
}
DocumentFeed> document = documentOpt.get();
feed = document.getRoot();
return Optional.of(feed);
}
public void closeStreamAndConnection() {
if (in != null) {
try {
in.close();
//System.out.println("\nInput Stream is closed");
} catch (IOException e1) {
e1.printStackTrace();
}
}
if (conn != null) {
conn.disconnect();
//System.out.println("Connection is disconnected");
}
}
/**
* This is just a safety check, if user forget to close the stram, it will
* be closed once object is out of scope.
*/
@Override
public void finalize() {
closeStreamAndConnection();
}
}
ParserDemo.java
import java.io.IOException;
import java.util.Optional;
import org.apache.abdera.Abdera;
import org.apache.abdera.model.Entry;
import org.apache.abdera.model.Feed;
import org.apache.abdera.parser.ParseException;
import org.apache.abdera.writer.Writer;
public class ParserDemo {
private static String url = "http://self-learning-java-tutorial.blogspot.in/atom.xml";
private static String id = "tag:blogger.com,1999:blog-3062500619105519975.post-8736482404064859734";
public static void main(String args[]) throws ParseException, IOException {
FeedUtil util = new FeedUtil(url);
OptionalFeed> feedOpt = util.getFeed();
if (!feedOpt.isPresent()) {
System.out.println("No feed present");
return;
}
Feed feed = feedOpt.get();
Entry entry = feed.getEntry(id);
/* Print the feed to console */
Writer writer = Abdera.getInstance().getWriterFactory().getWriter("prettyxml");
entry.writeTo(writer, System.out);
util.closeStreamAndConnection();
}
}
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