Rss,Atom聚合规范的XML文件解析(Rome,rssutils)

1.通过Rome插件可以简化对这两种规范文件的解析难度！Rss,Atom一般用在网站订阅功能，可以实现网络资源共享，用户可以通过客户端软件直接浏览各大网站已订阅的文章。简单的来说，电子订阅的特点就是，可以将多个网站上频繁更新的内容如：博客，新闻，聚合到一个网页列表上。ff可以下载sage插件解析，IE7可以直接解析。以下是读写操作的代码示例：

package rss;

import java.io.FileWriter;
import java.io.Writer;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import com.sun.syndication.feed.synd.SyndContent;
import com.sun.syndication.feed.synd.SyndContentImpl;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndEntryImpl;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.feed.synd.SyndFeedImpl;
import com.sun.syndication.io.SyndFeedOutput;

public class RssWrite {

	public static void main(String[] args) throws Exception {
		DateFormat dateParser = new SimpleDateFormat("yyyyMMddhhmmss");

		SyndFeed feed = new SyndFeedImpl();
		feed.setFeedType("atom_1.0");
		feed.setTitle("Sample Feed (created with Rome)");
    feed.setLink("http://rome.dev.java.net");
    feed.setDescription("This feed has been created using Rome (Java syndication utilities");
    feed.setEncoding("utf-8");//默认是utf-8

    List entries = new ArrayList();
    SyndEntry entry;
    SyndContent description;

    entry = new SyndEntryImpl(); // feed其中的一个 entry, 即其中一篇文章

    entry.setTitle("Rome v1.0");  // 设置文章标题
    entry.setLink("http://wiki.java.net/bin/view/Javawsxml/Rome01");
    entry.setPublishedDate(new Date());
    description = new SyndContentImpl(); // 文章的描述
    description.setType("text/plain");
    description.setValue("hello caohaigang");
    entry.setDescription(description);
    entries.add(entry);

    entry = new SyndEntryImpl();
    entry.setTitle("Rome v1.0");
    entry.setLink("http://wiki.java.net/bin/view/Javawsxml/Rome01");
    entry.setPublishedDate(new Date());
    description = new SyndContentImpl();
    description.setType("text/plain");
    description.setValue("<img src=\"http://farm4.static.flickr.com/3026/2645744338_bf6a7e9c57_m.jpg\" />");
    entry.setDescription(description);
    entries.add(entry);

    feed.setEntries(entries); // 设置feed的文章列表
    String path = "c:/xml";
    File f = new File(path);       
        if(!f.exists()){
        	f.mkdirs();  
        }
    String fileName = dateParser.format(new Date())+".xml";
    //FileWriter输出的XML文件为gb2312编码,这在linux下无法使用
    //Writer writer = new FileWriter(path + "/" + fileName);
    //要和正文编码设置一致
    Writer writer = new OutputStreamWriter(new FileOutputStream(fileName), "UTF-8");
    SyndFeedOutput output = new SyndFeedOutput();
    output.output(feed,writer); // 向客户端输出xml
    writer.close();

    System.out.println("The feed has been written to the file ["+fileName+"]");
	}
}

import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.fetcher.FeedFetcher;
import com.sun.syndication.fetcher.impl.FeedFetcherCache;
import com.sun.syndication.fetcher.impl.HashMapFeedInfoCache;
import com.sun.syndication.fetcher.impl.HttpURLFeedFetcher;

public class RssReader {

    public static void main(String[] args) throws Exception {
        FeedFetcherCache feedInfoCache = HashMapFeedInfoCache.getInstance();
        FeedFetcher feedFetcher = new HttpURLFeedFetcher(feedInfoCache);

        URL url = new URL("http://www.china-pub.com/rss/FeedPub.asp?id=3");
        //url是XML文件, 如http://feed.feedsky.com/xxx.xml
        SyndFeed feed = feedFetcher.retrieveFeed(url);
        List entryList = feed.getEntries();
        for (int i = 0; i < entryList.size(); i++) {
            SyndEntry entry = (SyndEntry) entryList.get(i);
            System.out.println("Published Date: " + entry.getPublishedDate());
            System.out.println("Title: " + entry.getTitle());
            System.out.println("Link: " + entry.getLink());
            SyndContent sc = entry.getDescription();
            if(sc!=null){
            	System.out.println("Description: " + sc.getValue());
            }
            System.out.println("------------------------------");
        }
    }
}

其中FeedType为以下同种中的一种

public static final String RSS_090 = "rss_0.9";
public static final String RSS_092 = "rss_0.92";
public static final String RSS_093 = "rss_0.93";
public static final String RSS_094 = "rss_0.94";
public static final String RSS_091_Netscape = "rss_0.91";
public static final String RSS_091_Userland = "rss_0.91";
public static final String RSS_100 = "rss_1.0";
public static final String RSS_200 = "rss_2.0";
public static final String ATOM_030 = "atom_0.3";
public static final String ATOM_100 = "atom_1.0";

用ROME ,就可以很简单的生成rss, atom或者将rss转化成atom, 等操作..
这个插件需要3个jar包 jdom.jar rome-0.9.jar rome-fetcher-0.9.jar

2.通过rssutils插件可以对RssXml进行读操作，引入jar包之后直接可以通过在jsp页写标签进行输出，优点：使用简单。缺点：仅仅只能对RssXml文件进行读取操作。

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib uri="/WEB-INF/rssutils.tld" prefix="rss" %>

<rss:feed
url="http://dev.csdn.net/rss/2.xml"
feedId="example1"/>
<b>Image: </b><rss:channelImage feedId="example1" asLink="true"/><br>
<b>Title: </b><rss:channelTitle feedId="example1"/><br>
<b>Link: </b><rss:channelLink feedId="example1" asLink="true"/><br>
<b>Description: </b><rss:channelDescription feedId="example1"/><br>
<ul>
  <rss:forEachItem feedId="example1">
    <li><rss:itemTitle feedId="example1"/><br>
    	<rss:itemLink feedId="example1"/><br>
    	<rss:itemDescription feedId="example1"/><br>
  </rss:forEachItem>
</ul>

需要rssutils.jar