/*
* Copyright 2002-2008 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.
*
* <p>Application-specific view classes will typically extend from either
* {@link AbstractRssFeedView} or {@link AbstractAtomFeedView} instead of from this class.
*
* <p>Thanks to Jettro Coenradie and Sergio Bossa for the original feed view prototype!
*
* @author Arjen Poutsma
* @author Juergen Hoeller
* @since 3.0
* @see AbstractRssFeedView
* @see AbstractAtomFeedView
*/
public abstract class AbstractFeedView<T extends WireFeed> extends AbstractView {
@Override
protected final void renderMergedOutputModel(
Map<String, Object> 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<String, Object> 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<String, Object> model, T feed,
HttpServletRequest request, HttpServletResponse response) throws Exception;
}