Sax解析Xml

对于解析大型的xml，可能使用整个document或整个文件都读到内存中是不合适的。
以下只是一个用例，sax解析是无状态的，也就是说他不知道上一次解析了什么，或下一次解析什么，他只知道解析的是当前行，所以这是流水线的，不会占大内存.

package org.frame.base.xml.jdk;

import java.io.IOException;
import java.io.StringReader;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

/**
 * foreigner 's xml paser is interesting.
 *
 * @author ycl
 * @version 1.0 2012-12-10 上午10:50:53
 * @since 1.0
 *
 */
public class JDKxmlSax {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		StringBuffer xml = new StringBuffer("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
		xml.append("<contact>");
		
		xml.append("<item>");
		xml.append("<uic>1</uic>");
		xml.append("<fullName>ycl1</fullName>");
		xml.append("</item>");
		
		xml.append("<item>");
		xml.append("<uic>2</uic>");
		xml.append("<fullName>ycl2</fullName>");
		xml.append("</item>");
		
		xml.append("</contact>");
		

		InputSource is = new InputSource(new StringReader(xml.toString()));
		ContactListXmlHandler handler = parse(is);
		System.out.println(handler.getContactNameList());
	}
	
	public static ContactListXmlHandler parse(InputSource input){
		ContactListXmlHandler handler = new ContactListXmlHandler();
		try {
		    SAXParserFactory factory = SAXParserFactory.newInstance();
		    SAXParser sp = factory.newSAXParser();
		    XMLReader xr = sp.getXMLReader();  
		    
		    xr.setContentHandler(handler);
		    xr.parse(input);
		} catch (ParserConfigurationException e) {
		    // TODO Auto-generated catch block
		    e.printStackTrace();
		} catch (SAXException e) {
		    // TODO Auto-generated catch block
		    e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return handler;
	}

}

package org.frame.base.xml.jdk;

import java.util.ArrayList;
import java.util.List;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class ContactListXmlHandler extends DefaultHandler implements Resources {

	private List<ContactName> contactNameList = new ArrayList<ContactName>();

	private ContactName contactItem;

	private StringBuffer sb;

	public List<ContactName> getContactNameList() {
		return contactNameList;
	}

	@Override
	public void startDocument() throws SAXException {
		// TODO Auto-generated method stub
		super.startDocument();
		sb = new StringBuffer();
	}

	@Override
	public void startElement(String uri, String localName, String qName,
			Attributes attributes) throws SAXException {
		super.startElement(uri, localName, qName, attributes);
		if (qName.equals(CONTACT_ITEM)) {
			contactItem = new ContactName();
		}
		sb.setLength(0); 
	}

	@Override
	public void characters(char[] ch, int start, int length)
			throws SAXException {
		try {
			super.characters(ch, start, length);
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		sb.append(ch, start, length);
	}

	@Override
	public void endDocument() throws SAXException {
		// TODO Auto-generated method stub
		super.endDocument();
	}

	@Override
	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		// TODO Auto-generated method stub
		if (contactItem != null) {
			if (qName.equalsIgnoreCase(ITEM_UIC)) {
				contactItem.setUid(sb.toString()); 

			} else if (qName.equalsIgnoreCase(ITEM_FULLNAME)) {
				contactItem.setFullName(sb.toString());

			} else if (qName.equalsIgnoreCase(CONTACT_ITEM)) { 
				contactNameList.add(contactItem);
			}

			sb.setLength(0);
		}
	}

}

package org.frame.base.xml.jdk;

import net.sf.json.JSONObject;

public class ContactName {

	private String uid;
	private String fullName;
	private String width;
	
	public String getWidth() {
		return width;
	}
	public void setWidth(String width) {
		this.width = width;
	}
	public String getUid() {
		return uid;
	}
	public void setUid(String uid) {
		this.uid = uid;
	}
	public String getFullName() {
		return fullName;
	}
	public void setFullName(String fullName) {
		this.fullName = fullName;
	}
	@Override
	public String toString() { 
		return "uid:"+uid+",fullName:"+fullName+",width:"+width;
	}
	
	
}