digester3解析xml(rss)手记

因为需要写个程序解析RSS，于是下载了最新的digester3版本：commons-digester3-3.2-bin.zip
http://commons.apache.org/proper/commons-logging/download_logging.cgi

用以前的惯常写法，一直不行。

public static void main(String[] args) {
 Digester digester = new Digester();
 hand.addRuleInstances(digester);
 Channel ch = digester.parse("d:/rss.xml");
}

public void addRuleInstances(Digester dig) {
		// TODO Auto-generated method stub
		dig.setValidating(false) ;
		dig.setNamespaceAware( true );
		
		dig.addObjectCreate("rss/channel", Channel.class) ;
		
		dig.addBeanPropertySetter("rss/channel/title", "title") ;
		dig.addBeanPropertySetter("rss/channel/link", "link") ;
		dig.addBeanPropertySetter("rss/channel/description", "description") ;
		dig.addBeanPropertySetter("rss/channel/copyright", "copyright") ;
		
		dig.addObjectCreate("rss/channel/item", Item.class) ;
		
		dig.addBeanPropertySetter("rss/channel/item/title", "title") ;
		dig.addBeanPropertySetter("rss/channel/item/link", "link") ;
		dig.addBeanPropertySetter("rss/channel/item/description", "description") ;
		dig.addBeanPropertySetter("rss/channel/item/pubDate", "pubDate") ;
		dig.addBeanPropertySetter("rss/channel/item/guid", "guid") ;
		
		dig.addSetNext("rss/channel/item", "addItem" ) ;
	}

一直报这样一个错

java.lang.UnsupportedOperationException: This parser does not support specification “null” version “null” 

查了下源码，分析原因，无外乎是说digester创建解析器失败。
自己手动建解析器，解决之

        SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
	this.digester = new Digester(parser) ;
	this.addRuleInstances(digester) ;

这样就能解决报错问题了。

附上封装的几个解析器

public Channel parse(File file ){
		Channel chan = null ;
		try {
			InputStream in = new FileInputStream(file);
			chan = this.digester.parse(in) ;
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		
		return chan ;
	}
	
	public Channel parse(String locationfile){
		return this.parse(new File(locationfile)) ;
	}
	
	/**
	 * 解析速度受网络影响
	 * @param url
	 * @return
	 */
	public Channel parse(URL url){
		Channel chan = null ;
		try {
			URLConnection feed = url.openConnection() ;
			feed.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; DigExt)");
			
			chan = this.digester.parse(feed.getInputStream() ) ;
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		
		return chan ;
	}

javabean

public class Channel {
	
	private final List<Item> items = new ArrayList<Item>();
	
	//@BeanPropertySetter( pattern = "rss/channel/title")
    private String title;

    //@BeanPropertySetter( pattern = "rss/channel/link")
    private String link;

    //@BeanPropertySetter( pattern = "rss/channel/description")
    private String description;

    //@BeanPropertySetter( pattern = "rss/channel/language")
    private String language;
    
    //@BeanPropertySetter( pattern = "rss/channel/copyright")
	private String copyright ;
	
    //@BeanPropertySetter( pattern = "rss/channel/dc:creator")
	private String creator ;
    
    //@BeanPropertySetter( pattern = "rss/channel/dc:rights")
	private String rights ;
。。。