sax解析 得到xml文档所有内容和获取指定标签的值

//得到xml文档所有内容

package cn.itcast.sax;

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.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

public class test1 {

	/**
	 * sax解析xml文档
	 * @throws SAXException 
	 * @throws ParserConfigurationException 
	 * @throws IOException 
	 */
	public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {
		
		//1.创建解析工厂
		SAXParserFactory factory = SAXParserFactory.newInstance();
		
		//2.得到解析器
		SAXParser sp = factory.newSAXParser();
		
		//3.得到读取器
		XMLReader reader = sp.getXMLReader();
		
		//4.设置内容处理器
		reader.setContentHandler(new ListHandler());
		
		//5.读取xml文档内容
		reader.parse("src/book.xml");

	}

}


//得到xml文档所有内容
class ListHandler implements ContentHandler{
	
	@Override
	public void startElement(String uri, String localName, String qName,
			Attributes atts) throws SAXException {
		System.out.println("<" + qName + ">");
		
		for(int i = 0; atts != null && i < atts.getLength(); i++){
			String attName = atts.getQName(i);
			String attValue = atts.getValue(i);
			System.out.println(attName + "=" + attValue);
		}
		
	}
	
	@Override
	public void characters(char[] ch, int start, int length)
			throws SAXException {
		System.out.println(new String(ch,start,length));
		
	}

	@Override
	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		System.out.println("</" + qName + ">");	
	}
	
	@Override
	public void setDocumentLocator(Locator locator) {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void startDocument() throws SAXException {
		// TODO Auto-generated method stub
		
	}

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

	@Override
	public void startPrefixMapping(String prefix, String uri)
			throws SAXException {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void endPrefixMapping(String prefix) throws SAXException {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void ignorableWhitespace(char[] ch, int start, int length)
			throws SAXException {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void processingInstruction(String target, String data)
			throws SAXException {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void skippedEntity(String name) throws SAXException {
		// TODO Auto-generated method stub
		
	}
	
}


//获取指定标签的值

package cn.itcast.sax;

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.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

public class Text2 {

	/**
	 * sax解析xml文档
	 * @throws SAXException 
	 * @throws ParserConfigurationException 
	 * @throws IOException 
	 */
	public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {
		
		//1.创建解析工厂
		SAXParserFactory factory = SAXParserFactory.newInstance();
		
		//2.得到解析器
		SAXParser sp = factory.newSAXParser();
		
		//3.得到读取器
		XMLReader reader = sp.getXMLReader();
		
		//4.设置内容处理器
		reader.setContentHandler(new TagValueHandler());
		
		//5.读取xml文档内容
		reader.parse("src/book.xml");

	}

}

//获取指定标签的值
class TagValueHandler extends DefaultHandler{

	private String currentTag;//记住当前解析的是什么标签
	private  int needNumber = 2;//记住想获取第几个作者标签的值
	private  int currentNumber;//当前解析的是第几个
	
	@Override
	public void startElement(String uri, String localName, String qName,
			Attributes attributes) throws SAXException {
		currentTag = qName;
		if(currentTag.equals("作者")){
			currentNumber++;
		}
	}

	@Override
	public void characters(char[] ch, int start, int length)
			throws SAXException {
		if("作者".equals(currentTag) && currentNumber == needNumber){
			System.out.println(new String(ch,start,length));
		}
		
	}
	
	@Override
	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		currentTag = null;
	}

	
}