廖雪峰Java14Java操作XML和JSON-1XML-3SAX

SAX：Simple API for XML

• 基于事件的API
  

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

public class SAXSample {
    static final String XML_URL = "http://rss.sina.com.cn/tech/internet/home28.xml";
    public static void main(String[] args) throws Exception{
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        sp.parse(XML_URL,new MyHandle());
    }
}

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

public class MyHandle extends DefaultHandler {
    void print(Object... objs){
        for(Object obj:objs){
            System.out.print(obj);
            System.out.print(" ");
        }
        System.out.println();
    }
    @Override
    public void startDocument() throws SAXException{ //开始解析文档时，就会触发startDocument事件
        print("start Document");
    }
    @Override
    public void endDocument() throws SAXException{ //解析结束时，会触发endDocument事件
        print("end Document");
    }
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException{ //如果遇到一个XML元素，会触发startElement事件
        print("start Element:",localName,qName);
    }
    @Override
    public void endElement(String uri,String localName,String qName) throws SAXException{ //元素结束时，会触发endElement事件
        print("end Element:",localName,qName);
    }
    @Override
    public void characters(char[] ch,int start,int length) throws SAXException{ //遇到文本，会触发characters事件
        print("characters:",new String(ch,start,length));
    }
    @Override
    public void error(SAXParseException e) throws SAXException{ //遇到错误，会触发error事件
        print("error:",e);
    }
}

总结：
SAX解析XML

• 一种流式解析XML的API
• 通过事件触发，速度快
• 调用方式通过回调获得数据