Java之XML解析的两种方法介绍

Java XML Parsing

解析XML有两种（不限于）方法： 一种是基于DOM（Document Object Model）的解析，一种是基于事件（event-based）的SAX（Sample API for XML）解析。

DOM    
-Tree model parser(Object based) (Tree of nodes).
-DOM 加载所有XML到内存，然后解析。因此具有内存限制。
-DOM 可以对XML进行读写操作。
-DOM 适宜于小型的XML。
-可以对节点进行前后检索。
-运行速度慢
-JDK 7 内置

SAX
-Event based parser (Sequence of events).
-SAX 按节点，一边读一边解析。因此没有内存限制。
-SAX 只能对XML进行读操作。
-SAX 可以解析大型的XML。
-SAX 从文件头读到文件尾，不可向后检索。
-运行速度快
-需要引用第三方包：jdom


示例：

XML（text.xml）

<?xml version="1.0"?>
<class>
   <student rollno="393">
      <firstname>dinkar</firstname>
      <lastname>kad</lastname>
      <nickname>dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno="493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno="593">
      <firstname>jasvir</firstname>
      <lastname>singn</lastname>
      <nickname>jazz</nickname>
      <marks>90</marks>
   </student>
</class>

DOM 解析

package com.gentleman.util.xml;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class DOMParser {
	
	public static void main(String[] args) throws Exception {
		
		DocumentBuilderFactory documentBuilderFactory 
			= DocumentBuilderFactory.newInstance();
		DocumentBuilder documentBuilder 
			= documentBuilderFactory.newDocumentBuilder();	
		Document document = documentBuilder.parse(
				DOMParser.class.getClassLoader().getResourceAsStream("test.xml"));
	
		document.getDocumentElement().normalize();
        
        System.out.println("Root Element : " +
        		document.getDocumentElement().getNodeName());
        System.out.println("----------------------------");
        
        NodeList nList = document.getElementsByTagName("student");        
        for (int temp = 0; temp < nList.getLength(); temp++) {
           Node node = nList.item(temp); 
           Element element = (Element) node;
           
           System.out.println(element.getNodeName() + " : " + 
        		   			  element.getAttribute("rollno"));
           System.out.println("First Name : " + getText(element, "firstname"));              
           System.out.println("Last Name : " +  getText(element, "lastname"));              
           System.out.println("Nick Name : "  +  getText(element, "nickname"));              
           System.out.println("Marks : "  +  getText(element, "marks"));
           System.out.println("\n");
        }

	}//end main().
	
	private static String getText(Element element, String tag){
		return element
                .getElementsByTagName(tag)
                .item(0)  // get the first element of the tag name.
                .getTextContent();
	}
}

SAX解析

package com.gentleman.util.xml;

import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;

public class SAXParser {

	public static void main(String[] args) throws Exception {
		SAXBuilder sb = new SAXBuilder();
		Document doc = sb.build(SAXParser.class.getClassLoader()
				.getResourceAsStream("test.xml"));
		Element root = doc.getRootElement();
		List list = root.getChildren("student");

		for (int i = 0; i < list.size(); i++) {
			Element element = (Element) list.get(i);

			String rollno = element.getAttributeValue("rollno");

			String firstname = element.getChildText("firstname");
			String lastname = element.getChildTextTrim("lastname");
			String nickname = element.getChild("nickname").getText();
			String marks = element.getChild("marks").getTextTrim();

			System.out.println("Student: " + rollno);
			System.out.println("---------------------------");
			System.out.println("firstname: " + firstname);
			System.out.println("lastname : " + lastname);
			System.out.println("nickname : " + nickname);
			System.out.println("marks    : " + marks);
			System.out.println("\n");

		}
	}
}

引用：
http://stackoverflow.com/a/19154095/2893073
https://docs.oracle.com/cd/B28359_01/appdev.111/b28394/adx_j_parser.htm#BGBGAJIA
https://docs.oracle.com/javase/tutorial/jaxp/dom/readingXML.html






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转载请注明
原文出处：http://lixh1986.iteye.com/blog/2328760

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