com.sun.syndication.fetcher.impl
Class HttpURLFeedFetcher

java.lang.Object
  com.sun.syndication.fetcher.impl.AbstractFeedFetcher
      com.sun.syndication.fetcher.impl.HttpURLFeedFetcher

All Implemented Interfaces:

FeedFetcher

public class HttpURLFeedFetcher

extends AbstractFeedFetcher

Class to retrieve syndication files via HTTP.

If passed a FeedFetcherCache in the constructor it will use conditional gets to only retrieve modified content.

The class uses the Accept-Encoding: gzip header to retrieve gzipped feeds where supported by the server.

Simple usage:

 	// create the cache
	FeedFetcherCache feedInfoCache = HashMapFeedInfoCache.getFeedInfoCache();
	// retrieve the feed the first time
	// any subsequent request will use conditional gets and only
	// retrieve the resource if it has changed
	SyndFeed feed = new HttpURLFeedFetcher(feedInfoCache).retrieveFeed(feedUrl);

Author:

Nick Lothian

See Also:

http://fishbowl.pastiche.org/2002/10/21/http_conditional_get_for_rss_hackers, http://diveintomark.org/archives/2003/07/21/atom_aggregator_behavior_http_level, http://bobwyman.pubsub.com/main/2004/09/using_rfc3229_w.html

Field Summary

private FeedFetcherCache	feedInfoCache
private IProgressMonitor	monitor The IProgressMonitor to report the progress of a newsfeed retrieval operation to.
(package private) static int	POLL_EVENT
(package private) static int	RETRIEVE_EVENT
(package private) static int	UNCHANGED_EVENT

Fields inherited from class com.sun.syndication.fetcher.impl.AbstractFeedFetcher

Fields inherited from interface com.sun.syndication.fetcher.FeedFetcher

DEFAULT_USER_AGENT

Constructor Summary

HttpURLFeedFetcher()
Constructor to use HttpURLFeedFetcher without caching of feeds

HttpURLFeedFetcher(FeedFetcherCache feedCache)
Constructor to enable HttpURLFeedFetcher to cache feeds

HttpURLFeedFetcher(FeedFetcherCache feedCache, IProgressMonitor monitor)
Constructor to enable HttpURLFeedFetcher to cache feeds and to report the progress of a newsfeed retrieval operation to the specified IProgressMonitor.

Method Summary

FeedFetcherCache	getFeedInfoCache()
IProgressMonitor	getProgressMonitor() Gets the IProgressMonitor used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation.
private SyndFeed	getSyndFeedFromStream(InputStream inputStream, URLConnection connection)
protected void	resetFeedInfo(URL orignalUrl, SyndFeedInfo syndFeedInfo, HttpURLConnection connection)
protected void	retrieveAndCacheFeed(URL feedUrl, SyndFeedInfo syndFeedInfo, HttpURLConnection connection)
SyndFeed	retrieveFeed(URL feedUrl) Retrieve a feed over HTTP
void	setFeedInfoCache(FeedFetcherCache cache)
void	setProgressMonitor(IProgressMonitor monitor) Sets the IProgressMonitor to be used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation.
protected void	setRequestHeaders(URLConnection connection, SyndFeedInfo syndFeedInfo) Set appropriate HTTP headers, including conditional get and gzip encoding headers

Methods inherited from class com.sun.syndication.fetcher.impl.AbstractFeedFetcher

addFetcherEventListener, combineFeeds, fireEvent, fireEvent, fireEvent, fireEvent, getUserAgent, handleErrorCodes, isUsingDeltaEncoding, removeFetcherEventListener, setUserAgent, setUsingDeltaEncoding, throw4XXError, throwAuthenticationError

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

POLL_EVENT

static final int POLL_EVENT

See Also:

Constant Field Values

RETRIEVE_EVENT

static final int RETRIEVE_EVENT

See Also:

Constant Field Values

UNCHANGED_EVENT

static final int UNCHANGED_EVENT

See Also:

Constant Field Values

feedInfoCache

private FeedFetcherCache feedInfoCache

monitor

private IProgressMonitor monitor

The IProgressMonitor to report the progress of a newsfeed retrieval operation to. Added by Sebastian Machhausen (Sebastian.Machhausen@gmail.com)

Constructor Detail

HttpURLFeedFetcher

public HttpURLFeedFetcher()

Constructor to use HttpURLFeedFetcher without caching of feeds

HttpURLFeedFetcher

public HttpURLFeedFetcher(FeedFetcherCache feedCache)

Constructor to enable HttpURLFeedFetcher to cache feeds

Parameters:

feedCache - - an instance of the FeedFetcherCache interface

HttpURLFeedFetcher

public HttpURLFeedFetcher(FeedFetcherCache feedCache,
                          IProgressMonitor monitor)

Constructor to enable HttpURLFeedFetcher to cache feeds and to report the progress of a newsfeed retrieval operation to the specified IProgressMonitor.

Parameters:

feedCache - an instance of the FeedFetcherCache interface

monitor - the IProgressMonitor used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation

Method Detail

retrieveFeed

public SyndFeed retrieveFeed(URL feedUrl)
                      throws IllegalArgumentException,
                             IOException,
                             FeedException,
                             FetcherException

Retrieve a feed over HTTP

Parameters:

feedUrl - A non-null URL of a RSS/Atom feed to retrieve

Returns:

A SyndFeed object

Throws:

IllegalArgumentException - if the URL is null;

IOException - if a TCP error occurs

FeedException - if the feed is not valid

FetcherException - if a HTTP error occurred

retrieveAndCacheFeed

protected void retrieveAndCacheFeed(URL feedUrl,
                                    SyndFeedInfo syndFeedInfo,
                                    HttpURLConnection connection)
                             throws IllegalArgumentException,
                                    FeedException,
                                    FetcherException,
                                    IOException

Throws:

IllegalArgumentException

FeedException

FetcherException

IOException

resetFeedInfo

protected void resetFeedInfo(URL orignalUrl,
                             SyndFeedInfo syndFeedInfo,
                             HttpURLConnection connection)
                      throws IllegalArgumentException,
                             IOException,
                             FeedException

Throws:

IllegalArgumentException

IOException

FeedException

setRequestHeaders

protected void setRequestHeaders(URLConnection connection,
                                 SyndFeedInfo syndFeedInfo)

Set appropriate HTTP headers, including conditional get and gzip encoding headers

Parameters:

connection - A URLConnection

syndFeedInfo - The SyndFeedInfo for the feed to be retrieved. May be null

getSyndFeedFromStream

private SyndFeed getSyndFeedFromStream(InputStream inputStream,
                                       URLConnection connection)
                                throws IOException,
                                       IllegalArgumentException,
                                       FeedException

Throws:

IOException

IllegalArgumentException

FeedException

getFeedInfoCache

public FeedFetcherCache getFeedInfoCache()

Returns:

The FeedFetcherCache used by this fetcher (Could be null)

setFeedInfoCache

public void setFeedInfoCache(FeedFetcherCache cache)

Parameters:

cache - The cache to be used by this fetcher (pass null to stop using a cache)

setProgressMonitor

public void setProgressMonitor(IProgressMonitor monitor)

Sets the IProgressMonitor to be used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation.

Parameters:

monitor - the IProgressMonitor to be used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation

getProgressMonitor

public IProgressMonitor getProgressMonitor()

Gets the IProgressMonitor used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation.

Returns:

the IProgressMonitor used by this HttpURLFeedFetcher to report the progress of a newsfeed retrieval operation