sax解析xml案例

浅浅的花香味﹌ 2022-08-12 14:59 168阅读 0赞

有一个xml文档

<?xml version="1.0" encoding="UTF-8" standalone="no"?><书架>
    	<书>
    		<书名 name="xxxx">java web</书名>
    		<作者>张大</作者>
    		<价格>102</价格>
    	</书>
    	<书>
    		<书名>spring</书名>
    		<作者>呜呜</作者>
    		<价格>55</价格>
    	</书>
    </书架>

解析所有节点

package cn.itcast.sax;
    
    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 Demo1 {
    	public static void main(String[] args) throws Exception {
    		
    		//1.创建工厂
    		SAXParserFactory saxP = SAXParserFactory.newInstance();
    		
    		//2.得到解析器
    		SAXParser parser = saxP.newSAXParser();
    		
    		//3.得到读取器
    		XMLReader xmlR = parser.getXMLReader();
    		
    		//4.设置内容处理器
    		xmlR.setContentHandler(new ParseS());
    		//5.读取xml内容
    		xmlR.parse("src/book.xml");
    	}
    }
    
    //得到xml文档的内容
    class ParseS implements ContentHandler{
    
    	@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 startElement(String uri, String localName, String qName,
    			Attributes atts) throws SAXException {
    		System.out.println("<"+qName+">");
    		for(int i=0; i<atts.getLength(); i++){
    			String name = atts.getQName(i);
    			String value = atts.getValue(i);
    			System.out.println(name+": "+value);
    		}
    	}
    
    	@Override
    	public void endElement(String uri, String localName, String qName)
    			throws SAXException {
    		System.out.println("</"+qName+">");
    		
    	}
    
    	@Override
    	public void characters(char[] ch, int start, int length)
    			throws SAXException {
    		System.out.println(new String(ch,start,length));
    		
    	}
    
    	@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 javax.xml.parsers.SAXParser;
    import javax.xml.parsers.SAXParserFactory;
    
    import org.xml.sax.Attributes;
    import org.xml.sax.SAXException;
    import org.xml.sax.XMLReader;
    import org.xml.sax.helpers.DefaultHandler;
    
    public class Demo2 {
    
    	public static void main(String[] args) throws Exception{
    		//1.创建工厂
    		SAXParserFactory saxP = SAXParserFactory.newInstance();
    		
    		//2.得到解析器
    		SAXParser parser = saxP.newSAXParser();
    		
    		//3.得到读取器
    		XMLReader xmlR = parser.getXMLReader();
    		
    		//4.设置内容处理器
    		xmlR.setContentHandler(new TagHandler());
    		//5.读取xml内容
    		xmlR.parse("src/book.xml");
    		
    	}
    
    }
    
    //获取指定标签的值
    class TagHandler extends DefaultHandler{
    	
    	private String currentTag;  //记录当前解析到的标签
    	private int needNum = 2;   //记录想获取第几个标签
    	private int currentNum;
    	
    	@Override
    	public void startElement(String uri, String localName, String qName,
    			Attributes attributes) throws SAXException {
    		currentTag = qName;
    		if("作者".equals(currentTag)){
    			currentNum++;
    		}
    	}
    
    	@Override
    	public void endElement(String uri, String localName, String qName)
    			throws SAXException {
    		currentTag = null;
    	}
    
    	@Override
    	public void characters(char[] ch, int start, int length)
    			throws SAXException {
    		if("作者".equals(currentTag) && currentNum==needNum){
    			System.out.println(new String(ch,start,length));
    		}
    	}
    	
    }