三十八毒

SAX是基于事件的API，运行比DOM更为底层的操作，相对DOM而言有更多的控制权，几乎总是比DOM效率高，不过它需要做更多的工作。。
下面的这个例子将打印出product.xml文档中所有的questions：

package sax.wkjava;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

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

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

public class SAXDemo {

	public SAXDemo() throws FileNotFoundException,
			ParserConfigurationException, SAXException, IOException {
		printQuestions("product.xml");
	}

	public static void main(String[] args) {
		try {
			new SAXDemo();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public void printQuestions(String xmlfile)
			throws ParserConfigurationException, SAXException,
			FileNotFoundException, IOException {

		SAXParserFactory factory = SAXParserFactory.newInstance();
		SAXParser parser = factory.newSAXParser();

		parser.parse(new FileInputStream(xmlfile), new DefaultHandler() {

			private boolean isQuestions = false;

			public void startElement(String uri, String localName,
					String qName, Attributes attributes)
					throws SAXException {
				if (qName.equals("questions")) {
					isQuestions = true;
				}
			}

			public void characters(char[] ch, int start, int length)
					throws SAXException {
				if (isQuestions) {
					String str = new String(ch, start, length);

					System.out.println(str);

				}
			}

			public void endElement(String uri, String localName,
					String qName) throws SAXException {
				if (qName.equals("questions")) {
					isQuestions = false;
				}
			}

		});
		
	}
}

//product.xml中code如下：
<?xml version="1.0" encoding="UTF-8"?>
<!-- product.xml -->
<product id="200">
	<name>UML Exam Simulator</name>
	<price>100</price>
	<topics name="UML">
		<topic id="UML_SM">
			<name>Static Modeling</name>
			<questions>100</questions>
		</topic>
		<topic id="UML_AE">
			<name>Architecture</name>
			<questions>80</questions>
		</topic>
		<topic id="UML_DM">
			<name>Dynamic Modeling</name>
			<questions>67</questions>
		</topic>
	</topics>
</product>