SPR-5249: Atom and RSS View

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/view/feed/AbstractAtomFeedView.java

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+/*
+ * Copyright 2008 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.servlet.view.feed;
+
+import java.util.List;
+import java.util.Map;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.sun.syndication.feed.WireFeed;
+import com.sun.syndication.feed.atom.Entry;
+import com.sun.syndication.feed.atom.Feed;
+
+/**
+ * Abstract superclass for Atom Feed views, using java.net's <a href="https://rome.dev.java.net/">ROME</a> package.
+ * Application-specific view classes will extend this class. The view will be held in the subclass itself, not in a
+ * template.
+ *
+ * <p/>Main entry points are the {@link #buildFeedMetadata(Map, WireFeed, HttpServletRequest)} and
+ * {@link #buildFeedEntries(Map, HttpServletRequest, HttpServletResponse)}.
+ *
+ * @author Jettro Coenradie
+ * @author Sergio Bossa
+ * @author Arjen Poutsma
+ * @since 3.0
+ * @see #buildFeedMetadata(Map, WireFeed, HttpServletRequest)
+ * @see #buildFeedEntries(Map, HttpServletRequest, HttpServletResponse)
+ */
+public abstract class AbstractAtomFeedView extends AbstractFeedView<Feed> {
+
+	public static final String DEFAULT_FEED_TYPE = "atom_1.0";
+
+	private String feedType = DEFAULT_FEED_TYPE;
+
+	/** Sets the appropriate content type: "application/atom+xml". */
+	public AbstractAtomFeedView() {
+		setContentType("application/atom+xml");
+	}
+
+	/**
+	 * Sets the Rome feed type to use.
+	 * <p/>
+	 * Defaults to Atom 1.0.
+	 *
+	 * @see Feed#setFeedType(String)
+	 * @see #DEFAULT_FEED_TYPE
+	 */
+	public void setFeedType(String feedType) {
+		this.feedType = feedType;
+	}
+
+	/**
+	 * Create a new feed to hold the entries.
+	 * <p/>
+	 * By default returns an Atom 1.0 feed, but the subclass can specify any Feed.
+	 *
+	 * @return the newly created Feed instance
+	 * @see #setFeedType(String)
+	 * @see com.sun.syndication.feed.atom.Feed#Feed(String)
+	 */
+	@Override
+	protected Feed newFeed() {
+		return new Feed(feedType);
+	}
+
+	/** Invokes {@link #buildFeedEntries(Map, HttpServletRequest, HttpServletResponse)} to get a list of feed entries. */
+	@Override
+	protected final void buildFeedEntries(Map model,
+										  Feed feed,
+										  HttpServletRequest request,
+										  HttpServletResponse response) throws Exception {
+		List<Entry> entries = buildFeedEntries(model, request, response);
+		feed.setEntries(entries);
+	}
+
+	/**
+	 * Subclasses must implement this method to build feed entries, given the model.
+	 * <p/>
+	 * Note that the passed-in HTTP response is just supposed to be used for setting cookies or other HTTP headers. The
+	 * built feed itself will automatically get written to the response after this method returns.
+	 *
+	 * @param model	the model Map
+	 * @param request  in case we need locale etc. Shouldn't look at attributes.
+	 * @param response in case we need to set cookies. Shouldn't write to it.
+	 * @return the feed entries to be added to the feed
+	 * @throws Exception any exception that occured during document building
+	 * @see Entry
+	 */
+	protected abstract List<Entry> buildFeedEntries(Map model, HttpServletRequest request, HttpServletResponse response)
+			throws Exception;
+}

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/view/feed/AbstractFeedView.java

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+/*
+ * Copyright 2008 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.servlet.view.feed;
+
+import java.io.OutputStreamWriter;
+import java.util.Map;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.sun.syndication.feed.WireFeed;
+import com.sun.syndication.io.WireFeedOutput;
+
+import org.springframework.util.StringUtils;
+import org.springframework.web.servlet.view.AbstractView;
+
+/**
+ * Abstract base class for Atom and RSS Feed views, using java.net's <a href="https://rome.dev.java.net/">ROME</a>
+ * package. TypApplication-specific view classes will typically extends either {@link AbstractRssFeedView} or {@link
+ * AbstractAtomFeedView}, not this class.
+ *
+ * @author Jettro Coenradie
+ * @author Sergio Bossa
+ * @author Arjen Poutsma
+ * @see AbstractRssFeedView
+ * @see AbstractAtomFeedView
+ * @since 3.0
+ */
+public abstract class AbstractFeedView<T extends WireFeed> extends AbstractView {
+
+	@Override
+	protected final void renderMergedOutputModel(Map model, HttpServletRequest request, HttpServletResponse response)
+			throws Exception {
+		T wireFeed = newFeed();
+		buildFeedMetadata(model, wireFeed, request);
+		buildFeedEntries(model, wireFeed, request, response);
+
+		response.setContentType(getContentType());
+		if (!StringUtils.hasText(wireFeed.getEncoding())) {
+			wireFeed.setEncoding("UTF-8");
+		}
+
+		WireFeedOutput feedOutput = new WireFeedOutput();
+		ServletOutputStream out = response.getOutputStream();
+		feedOutput.output(wireFeed, new OutputStreamWriter(out, wireFeed.getEncoding()));
+		out.flush();
+	}
+
+	/**
+	 * Create a new feed to hold the entries.
+	 *
+	 * @return the newly created Feed instance
+	 */
+	protected abstract T newFeed();
+
+	/**
+	 * Populate the feed metadata (title, link, description, etc.).
+	 * <p/>
+	 * Default is an empty implementation. Subclasses can override this method to add meta fields such as title, link
+	 * description, etc.
+	 *
+	 * @param model   the model, in case meta information must be populated from it
+	 * @param feed	the feed being populated
+	 * @param request in case we need locale etc. Shouldn't look at attributes.
+	 */
+	protected void buildFeedMetadata(Map model, T feed, HttpServletRequest request) {
+	}
+
+	/**
+	 * Subclasses must implement this method to build feed entries, given the model.
+	 * <p/>
+	 * Note that the passed-in HTTP response is just supposed to be used for setting cookies or other HTTP headers. The
+	 * built feed itself will automatically get written to the response after this method returns.
+	 *
+	 * @param model	the model Map
+	 * @param feed	 the feed to add entries to
+	 * @param request  in case we need locale etc. Shouldn't look at attributes.
+	 * @param response in case we need to set cookies. Shouldn't write to it.
+	 * @throws Exception any exception that occured during building
+	 */
+	protected abstract void buildFeedEntries(Map model,
+											 T feed,
+											 HttpServletRequest request,
+											 HttpServletResponse response) throws Exception;
+
+
+}

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/view/feed/AbstractRssFeedView.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2008 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.servlet.view.feed;
+
+import java.util.List;
+import java.util.Map;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.sun.syndication.feed.WireFeed;
+import com.sun.syndication.feed.rss.Channel;
+import com.sun.syndication.feed.rss.Item;
+
+/**
+ * Abstract superclass for RSS Feed views, using java.net's <a href="https://rome.dev.java.net/">ROME</a> package.
+ * Application-specific view classes will extend this class. The view will be held in the subclass itself, not in a
+ * template.
+ *
+ * <p/>Main entry points are the {@link #buildFeedMetadata(Map, WireFeed , HttpServletRequest)} and {@link
+ * #buildFeedItems(Map, HttpServletRequest, HttpServletResponse)}.
+ *
+ * @author Jettro Coenradie
+ * @author Sergio Bossa
+ * @author Arjen Poutsma
+ * @see #buildFeedMetadata(Map, WireFeed , HttpServletRequest)
+ * @see #buildFeedItems(Map, HttpServletRequest, HttpServletResponse)
+ * @since 3.0
+ */
+public abstract class AbstractRssFeedView extends AbstractFeedView<Channel> {
+
+	/** Sets the appropriate content type: "application/rss+xml". */
+	protected AbstractRssFeedView() {
+		setContentType("application/rss+xml");
+	}
+
+	/**
+	 * Create a new channel to hold the entries.
+	 *
+	 * <p/>By default returns an RSS 2.0 channel, but the subclass can specify any channel.
+	 *
+	 * @return the newly created Feed instance
+	 * @see Channel#Channel(String)
+	 */
+	@Override
+	protected Channel newFeed() {
+		return new Channel("rss_2.0");
+	}
+
+	/** Invokes {@link #buildFeedItems(Map, HttpServletRequest, HttpServletResponse)} to get a list of feed items. */
+	@Override
+	protected final void buildFeedEntries(Map model,
+										  Channel channel,
+										  HttpServletRequest request,
+										  HttpServletResponse response) throws Exception {
+		List<Item> items = buildFeedItems(model, request, response);
+		channel.setItems(items);
+	}
+
+	/**
+	 * Subclasses must implement this method to build feed items, given the model.
+	 *
+	 * <p/>Note that the passed-in HTTP response is just supposed to be used for setting cookies or other HTTP headers. The
+	 * built feed itself will automatically get written to the response after this method returns.
+	 *
+	 * @param model	the model Map
+	 * @param request  in case we need locale etc. Shouldn't look at attributes.
+	 * @param response in case we need to set cookies. Shouldn't write to it.
+	 * @return the feed items to be added to the feed
+	 * @throws Exception any exception that occured during document building
+	 * @see Item
+	 */
+	protected abstract List<Item> buildFeedItems(Map model, HttpServletRequest request, HttpServletResponse response)
+			throws Exception;
+}

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/view/feed/package.html

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+<html>
+<body>
+Support classes for feed generation, providing View implementations for Atom and RSS.
+</body>
+</html>