適用于Atom Feed的Spring MVC

如何僅使用兩個類就將提要（Atom）添加到Web應用程序？
Spring MVC呢？

這是我的假設：

您正在使用Spring框架
您有一些要發布在供稿中的實體，例如“新聞”
您的“新聞”實體具有creationDate，title和shortDescription
您有一些存儲庫/倉庫，例如“ NewsRepository”，它將從數據庫中返回新聞
你想寫得盡可能少
您不想手動格式化Atom（xml）

實際上，您實際上不需要在應用程序中使用Spring MVC。如果這樣做，請跳至步驟3。

步驟1：將Spring MVC依賴項添加到您的應用程序

使用Maven將是：

<dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>3.1.0.RELEASE</version>
</dependency>

步驟2：添加Spring MVC DispatcherServlet

使用web.xml將是：

<servlet><servlet-name>dispatcher</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:spring-mvc.xml</param-value></init-param><load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping><servlet-name>dispatcher</servlet-name><url-pattern>/feed</url-pattern>
</servlet-mapping>

注意，我將url-pattern設置為“ / feed”，這意味著我不希望Spring MVC處理我的應用程序中的任何其他URL（我在其余的應用程序中使用了不同的Web框架）。我還給它提供了一個全新的contextConfigLocation，其中僅保留了mvc配置。

請記住，將DispatcherServlet添加到已經具有Spring的應用程序時（例如，從ContextLoaderListener繼承），您的上下文是從全局實例繼承的，因此您不應創建在該全局實例中再次存在的bean，也不應該包含定義它們的xml。注意兩次Spring上下文，并查閱spring或servlet文檔以了解發生了什么。

步驟3.添加ROME –處理Atom格式的庫

與Maven是：

<dependency><groupId>net.java.dev.rome</groupId><artifactId>rome</artifactId><version>1.0.0</version>
</dependency>

步驟4.編寫非常簡單的控制器

@Controller
public class FeedController {static final String LAST_UPDATE_VIEW_KEY = 'lastUpdate';static final String NEWS_VIEW_KEY = 'news';private NewsRepository newsRepository;private String viewName;protected FeedController() {} //required by cglibpublic FeedController(NewsRepository newsRepository, String viewName) {notNull(newsRepository); hasText(viewName);this.newsRepository = newsRepository;this.viewName = viewName;}@RequestMapping(value = '/feed', method = RequestMethod.GET)        @Transactionalpublic ModelAndView feed() {ModelAndView modelAndView = new ModelAndView();modelAndView.setViewName(viewName);List<News> news = newsRepository.fetchPublished();modelAndView.addObject(NEWS_VIEW_KEY, news);modelAndView.addObject(LAST_UPDATE_VIEW_KEY, getCreationDateOfTheLast(news));return modelAndView;}private Date getCreationDateOfTheLast(List<News> news) {if(news.size() > 0) {return news.get(0).getCreationDate();}return new Date(0);}
}

如果您想復制并粘貼（誰不想要），這里有一個測試：

@RunWith(MockitoJUnitRunner.class)
public class FeedControllerShould {@Mock private NewsRepository newsRepository;private Date FORMER_ENTRY_CREATION_DATE = new Date(1);private Date LATTER_ENTRY_CREATION_DATE = new Date(2);private ArrayList<News> newsList;private FeedController feedController;@Beforepublic void prepareNewsList() {News news1 = new News().title('title1').creationDate(FORMER_ENTRY_CREATION_DATE);News news2 = new News().title('title2').creationDate(LATTER_ENTRY_CREATION_DATE);newsList = newArrayList(news2, news1);}@Beforepublic void prepareFeedController() {feedController = new FeedController(newsRepository, 'viewName');}@Testpublic void returnViewWithNews() {//givengiven(newsRepository.fetchPublished()).willReturn(newsList);//whenModelAndView modelAndView = feedController.feed();//thenassertThat(modelAndView.getModel()).includes(entry(FeedController.NEWS_VIEW_KEY, newsList));}@Testpublic void returnViewWithLastUpdateTime() {//givengiven(newsRepository.fetchPublished()).willReturn(newsList);//whenModelAndView modelAndView = feedController.feed();//thenassertThat(modelAndView.getModel()).includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, LATTER_ENTRY_CREATION_DATE));}@Testpublic void returnTheBeginningOfTimeAsLastUpdateInViewWhenListIsEmpty() {//givengiven(newsRepository.fetchPublished()).willReturn(new ArrayList<News>());//whenModelAndView modelAndView = feedController.feed();//thenassertThat(modelAndView.getModel()).includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, new Date(0)));}
}

注意：在這里，我正在使用fest-assert和mockito。依賴項是：

<dependency><groupId>org.easytesting</groupId><artifactId>fest-assert</artifactId><version>1.4</version><scope>test</scope>
</dependency>
<dependency><groupId>org.mockito</groupId><artifactId>mockito-all</artifactId><version>1.8.5</version><scope>test</scope>
</dependency>

步驟5.編寫非常簡單的視圖

這是所有魔術格式化發生的地方。一定要看一看Entry類的所有方法，因為您可能想使用/填充很多東西。

import org.springframework.web.servlet.view.feed.AbstractAtomFeedView;
[...]public class AtomFeedView extends AbstractAtomFeedView {private String feedId = 'tag:yourFantastiSiteName';private String title = 'yourFantastiSiteName: news';private String newsAbsoluteUrl = 'http://yourfanstasticsiteUrl.com/news/'; @Overrideprotected void buildFeedMetadata(Map<String, Object> model, Feed feed, HttpServletRequest request) {feed.setId(feedId);feed.setTitle(title);setUpdatedIfNeeded(model, feed);}private void setUpdatedIfNeeded(Map<String, Object> model, Feed feed) {@SuppressWarnings('unchecked')Date lastUpdate = (Date)model.get(FeedController.LAST_UPDATE_VIEW_KEY);if (feed.getUpdated() == null || lastUpdate != null || lastUpdate.compareTo(feed.getUpdated()) > 0) {feed.setUpdated(lastUpdate);}}@Overrideprotected List<Entry> buildFeedEntries(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {@SuppressWarnings('unchecked')List<News> newsList = (List<News>)model.get(FeedController.NEWS_VIEW_KEY);List<Entry> entries = new ArrayList<Entry>();for (News news : newsList) {addEntry(entries, news);}return entries;}private void addEntry(List<Entry> entries, News news) {Entry entry = new Entry();entry.setId(feedId + ', ' + news.getId());entry.setTitle(news.getTitle());entry.setUpdated(news.getCreationDate());entry = setSummary(news, entry);entry = setLink(news, entry);entries.add(entry);}private Entry setSummary(News news, Entry entry) {Content summary = new Content();summary.setValue(news.getShortDescription());entry.setSummary(summary);return entry;}private Entry setLink(News news, Entry entry) {Link link = new Link();link.setType('text/html');link.setHref(newsAbsoluteUrl + news.getId()); //because I have a different controller to show news at http://yourfanstasticsiteUrl.com/news/IDentry.setAlternateLinks(newArrayList(link));return entry;}}

步驟6.將類添加到Spring上下文

我正在使用xml方法。因為我老了，我喜歡xml。不，很認真，我使用xml是因為我可能想用不同的視圖（RSS 1.0，RSS 2.0等）聲明FeedController幾次。

這就是前面提到的spring-mvc.xml

<?xml version='1.0' encoding='UTF-8'?>
<beans xmlns='http://www.springframework.org/schema/beans'xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'xsi:schemaLocation='http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd'><bean class='org.springframework.web.servlet.view.ContentNegotiatingViewResolver'><property name='mediaTypes'><map><entry key='atom' value='application/atom+xml'/><entry key='html' value='text/html'/></map></property><property name='viewResolvers'><list><bean class='org.springframework.web.servlet.view.BeanNameViewResolver'/></list></property></bean><bean class='eu.margiel.pages.confitura.feed.FeedController'><constructor-arg index='0' ref='newsRepository'/><constructor-arg index='1' value='atomFeedView'/></bean><bean id='atomFeedView' class='eu.margiel.pages.confitura.feed.AtomFeedView'/>
</beans>

您完成了。

之前曾有人要求我將所有工作代碼放入某個公共存儲庫中，所以這又是另一回事了。我已經描述了我已經發布的內容，您可以從bitbucket中獲取提交。

參考： Solid Craft博客上來自我們JCG合作伙伴 Jakub Nabrdalik的Atom Feeds與Spring MVC 。