(备忘录)xml文件的生成和解析_SAX_2

一边加载一边解析，速度快，内存占用小，但是如果再次使用时需要再次解析：

当解析器发现元素开始、元素结束、文本、文档的开始或结束等时，发送事件，程序员编写响应这些事件的代码，保存数据。优点：不用事先调入整个文档，占用资源少；SAX解析器代码比DOM解析器代码小，适于Applet，下载。缺点：不是持久的；事件过后，若没保存数据，那么数据就丢了；无状态性；从事件中只能得到文本，但不知该文本属于哪个元素；使用场合：Applet;只需XML文档的少量内容，很少回头访问；机器内存少

package com.ailk.xmlparserdemon;

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

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;

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

import com.ailk.xmlparserdemon.intf.XmlDocument;

public class SaxXmlDemon implements XmlDocument {
	static String filename;

	public void createDocument(String fileName) {
		try {
			StreamResult result=new StreamResult(new FileOutputStream(filename));
			SAXTransformerFactory sf=(SAXTransformerFactory) SAXTransformerFactory.newInstance();
			TransformerHandler th=sf.newTransformerHandler();
			th.setResult(result);
			
			Transformer tf=th.getTransformer();
			tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
			tf.setOutputProperty(OutputKeys.INDENT, "yes");
			
			th.startDocument();
			AttributesImpl atts=new AttributesImpl();
			th.startElement("", "", "employees", atts);
			th.startElement("", "", "employee", atts);
			
			th.startElement("", "", "name", atts);
			th.characters("小明".toCharArray(), 0, "小明".length());
			th.endElement("", "", "name");
			
			th.startElement("", "", "sex", atts);
			th.characters("m".toCharArray(), 0, "m".length());
			th.endElement("", "", "sex");
			
			th.startElement("", "", "parents", atts);
			
			th.startElement("", "", "father", atts);
			th.characters("小张".toCharArray(), 0, "小张".length());
			th.endElement("", "", "father");
			
			th.startElement("", "", "mother", atts);
			th.characters("小慧".toCharArray(), 0, "小慧".length());
			th.endElement("", "", "mother");
			
			th.endElement("", "", "parents");
			
			th.endElement("", "", "employee");
			th.endElement("", "", "employees");
			
			th.endDocument();
			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (TransformerConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (TransformerFactoryConfigurationError e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		

	}

	public void parserDocument(String fileName) {
		SAXParserFactory saxfac = SAXParserFactory.newInstance();
		try {
			SAXParser saxparser = saxfac.newSAXParser();
			InputStream is = new FileInputStream(fileName);
			saxparser.parse(is, new MySAXHandler());
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		SaxXmlDemon sax = new SaxXmlDemon();
		SaxXmlDemon.filename = "E:\\OneNote\\dom1.xml";
		sax.createDocument(filename);
		sax.parserDocument(filename);
	}

}

class MySAXHandler extends DefaultHandler {
	boolean hasAttribute = false;
	Attributes attributes = null;

	public void startDocument() throws SAXException {
		System.out.println("文档开始打印了");
	}

	public void endDocument() throws SAXException {
		System.out.println("文档打印结束了");
	}

	public void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {
		if (qName.equals("employees")) {
			return;
		}
		if (qName.equals("employee")) {
			System.out.println(qName);
		}
		if (attributes.getLength() > 0) {
			this.attributes = attributes;
			this.hasAttribute = true;
		}
	}

	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		if (hasAttribute && (attributes != null)) {
			for (int i = 0; i < attributes.getLength(); i++) {
				System.out.println(attributes.getQName(0)
						+ attributes.getValue(0));
			}
		}
	}

	public void characters(char[] ch, int start, int length)throws SAXException {
		System.out.println(new String(ch, start, length));
	}
}