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>