sax解析原理与案例

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

public class Demo {
    
    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {
        //1、创建解析工程
        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");
    }

}

package itcast.sax;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
//获取指定标签值
public class TagValueHandler extends DefaultHandler {
    
    private String currentTag;//记住当前解析到的是什么标签
    private int needNumber=1;
    private int currentNumber;

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

    @Override
    public void endElement(String uri, String localName, String name)
            throws SAXException {
    
        currentTag=null;
    }

    @Override
    public void startElement(String uri, String localName, String name,
            Attributes atts) throws SAXException {
    
        currentTag=name;
        if(currentTag.equals("editor")){
            currentNumber++;
        }
    }
    
}

package itcast.sax;

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

public class ListHandle implements ContentHandler {
    @Override
    public void startElement(String uri, String localName, String name,
            Attributes atts) throws SAXException {

        System.out.println("<" + name + ">");
        
        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 name)
            throws SAXException {
        System.out.println("<" + name + ">");
    }

    @Override
    public void startDocument() throws SAXException {

    }

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

    }

    @Override
    public void endPrefixMapping(String arg0) throws SAXException {
        // TODO Auto-generated method stub

    }

    @Override
    public void ignorableWhitespace(char[] arg0, int arg1, int arg2)
            throws SAXException {
        // TODO Auto-generated method stub

    }

    @Override
    public void processingInstruction(String arg0, String arg1)
            throws SAXException {
        // TODO Auto-generated method stub

    }

    @Override
    public void setDocumentLocator(Locator arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void skippedEntity(String arg0) throws SAXException {
        // TODO Auto-generated method stub

    }

    @Override
    public void startPrefixMapping(String arg0, String arg1)
            throws SAXException {
        // TODO Auto-generated method stub

    }

}

<?xml version="1.0" encoding="UTF-8"?>
<书架>
    <书>
        <bookname name="zero">java jiuyepeixunjiaocheng</bookname>
        <editor>zhangxiaoxiang</editor>
        <price>109yuan</price>
    </书>
    <书>
        <bookname>javaWebprogramming</bookname>
        <editor>lihuoming</editor>
        <price>28.00yuan</price>
    </书>
</书架>