How To Read XML File In Java – (SAX Parser)

原文地址：http://www.mkyong.com/java/how-to-read-xml-file-in-java-sax-parser/

SAX parseris work differently with DOM parser,it either load any XML document into memory nor create any object representation of the XML document. Instead,the SAX parser use callback function (org.xml.sax.helpers.DefaultHandler) to informs clients of the XML document structure.

SAX Parser is faster and uses less memory than DOM parser.

See following SAX callback methods :

• startDocument()andendDocument()– Method called at the start and end of an XML document.
• startElement()andendElement()– Method called at the start and end of a document element.
• characters()– Method called with the text contents in between the start and end tags of an XML document element.

1. XML file

Create a simple XML file.

<?xml version="1.0"?>
<company>
	<staff>
		<firstname>yong</firstname>
		<lastname>mook kim</lastname>
		<nickname>mkyong</nickname>
		<salary>100000</salary>
	</staff>
	<staff>
		<firstname>low</firstname>
		<lastname>yin fong</lastname>
		<nickname>fong fong</nickname>
		<salary>200000</salary>
	</staff>
</company>

2. Java file

Use SAX parser to parse the XML file.

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
 
public class readxmlFile {
 
   public static void main(String argv[]) {
 
    try {
 
	SAXParserFactory factory = SAXParserFactory.newInstance();
	SAXParser saxParser = factory.newSAXParser();
 
	DefaultHandler handler = new DefaultHandler() {
 
	boolean bfname = false;
	boolean blname = false;
	boolean bnname = false;
	boolean bsalary = false;
 
	public void startElement(String uri,String localName,String qName,Attributes attributes) throws SAXException {
 
		System.out.println("Start Element :" + qName);
 
		if (qName.equalsIgnoreCase("FirsTNAME")) {
			bfname = true;
		}
 
		if (qName.equalsIgnoreCase("LASTNAME")) {
			blname = true;
		}
 
		if (qName.equalsIgnoreCase("NICKNAME")) {
			bnname = true;
		}
 
		if (qName.equalsIgnoreCase("SALARY")) {
			bsalary = true;
		}
 
	}
 
	public void endElement(String uri,String qName) throws SAXException {
 
		System.out.println("End Element :" + qName);
 
	}
 
	public void characters(char ch[],int start,int length) throws SAXException {
 
		if (bfname) {
			System.out.println("First Name : " + new String(ch,start,length));
			bfname = false;
		}
 
		if (blname) {
			System.out.println("Last Name : " + new String(ch,length));
			blname = false;
		}
 
		if (bnname) {
			System.out.println("Nick Name : " + new String(ch,length));
			bnname = false;
		}
 
		if (bsalary) {
			System.out.println("Salary : " + new String(ch,length));
			bsalary = false;
		}
 
	}
 
     };
 
       saxParser.parse("c:\\file.xml",handler);
 
     } catch (Exception e) {
       e.printstacktrace();
     }
 
   }
 
}

Result

Start Element :company Start Element :staff Start Element :firstname First Name : yong End Element :firstname Start Element :lastname Last Name : mook kim End Element :lastname Start Element :nickname Nick Name : mkyong End Element :nickname Start Element :salary Salary : 100000 End Element :salary End Element :staff Start Element :staff Start Element :firstname First Name : low End Element :firstname Start Element :lastname Last Name : yin fong End Element :lastname Start Element :nickname Nick Name : fong fong End Element :nickname Start Element :salary Salary : 200000 End Element :salary End Element :staff End Element :company