MyException - 我的异常网
当前位置:我的异常网» XML/SOAP » 使用java读取xml文件-DOM 解析

使用java读取xml文件-DOM 解析

www.MyException.Cn  网友分享于:2013-03-26  浏览:12次
运用java读取xml文件---DOM 解析

读取本地的xml文件,通过DOM进行解析,DOM解析的特点就是把整个xml文件装载入内存中,形成一颗DOM树形结构,树结构是方便遍历和和操纵。

DOM解析的特性就是读取xml文件转换为 dom树形结构,通过节点进行遍历。

这是W3c关于节点的概念

如果xml中包含有大量的数据,由于dom一次性把xml装入内存中的特性,所以dom不适合于包含大量数据的xml解析。当包含有大量xml的时候,用SAX进行解析比较节省内存。

下面是一个运用DOM进行解析xml文件的例子:

xml文件结构如下:

<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">XQuery Kick Start</title>
    <author>James McGovern</author>
    <year>2003</year>
    <price>49.99</price>
  </book>
  <book category="web" cover="paperback">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>


创建解析xml的类如下:

package xml.dom;

import java.io.File;
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 ReadXmlFile {
	
   public static void main(String[] args)  {
	   
	   try{
		   
		   File  xmlFile = new File("src/resource/book.xml");
		   
		   DocumentBuilderFactory  builderFactory =  DocumentBuilderFactory.newInstance();
		   
		   DocumentBuilder   builder = builderFactory.newDocumentBuilder();
		   
		   Document  doc = builder.parse(xmlFile);
		   
		   doc.getDocumentElement().normalize();
		   
		   System.out.println("Root  element: "+doc.getDocumentElement().getNodeName());
		   
		   NodeList  nList = doc.getElementsByTagName("book");
		   
		   for(int  i = 0 ; i<nList.getLength();i++){
			   
			   	Node  node = nList.item(i);
			   	
			   	System.out.println("Node name: "+ node.getNodeName());
			   	Element  ele = (Element)node;
			   	
			   	System.out.println("----------------------------");
			   	if(node.getNodeType() == Element.ELEMENT_NODE){
			   		
			   		System.out.println("book category: "+ ele.getAttribute("category"));
			   		
			   		System.out.println("title name: "+ ele.getElementsByTagName("title").item(0).getTextContent());
			   		
			   		System.out.println("author name: "+ele.getElementsByTagName("author").item(0).getTextContent());
			   		
			   		System.out.println("year :"+ele.getElementsByTagName("year").item(0).getTextContent());
			   		
			   		System.out.println("price : "+ele.getElementsByTagName("price").item(0).getTextContent());
			   		
			   		System.out.println("-------------------------");
			   		
			   		
			   	}
			   
			   
		   }
		   
解析结果:

Root  element: bookstore
Node name: book
----------------------------
book category: cooking
title name: Everyday Italian
author name: Giada De Laurentiis
year :2005
price : 30.00
-------------------------
Node name: book
----------------------------
book category: children
title name: Harry Potter
author name: J K. Rowling
year :2005
price : 29.99
-------------------------
Node name: book
----------------------------
book category: web
title name: XQuery Kick Start
author name: James McGovern
year :2003
price : 49.99
-------------------------
Node name: book
----------------------------
book category: web
title name: Learning XML
author name: Erik T. Ray
year :2003
price : 39.95
-------------------------

以上是通过name获得对应的值,

下面利用循环节点的方式输出:

循环节点输出方式的代码如下:

package xml.dom;

import java.io.File;

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

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

public class ReadXmlFile2 {
	
 public static void main(String[] args) {
   try{
		   
		   File  xmlFile = new File("src/resource/book.xml");
		   
		   DocumentBuilderFactory  builderFactory =  DocumentBuilderFactory.newInstance();
		   
		   DocumentBuilder   builder = builderFactory.newDocumentBuilder();
		   
		   Document  doc = builder.parse(xmlFile);
		   
		   doc.getDocumentElement().normalize();
		   
		   System.out.println("Root  element: "+doc.getDocumentElement().getNodeName());
		   
		   
		   if(doc.hasChildNodes()){
			   
			   printNode(doc.getChildNodes());
		   }
   }catch(Exception  e){
	   
	   e.printStackTrace();
	   
   }
 
 }
 
 public  static  void  printNode(NodeList nodeList){
	 System.out.println("------------------------");
	// System.out.println(nodeList.getLength());
	 for(int i = 0;  i<nodeList.getLength(); i++){
		 
		 Node  node = (Node)nodeList.item(i);
		 
		
		 if(node.getNodeType() == Node.ELEMENT_NODE){
			 
			 System.out.println("node name: "+node.getNodeName());
			 
			 System.out.println("node value: "+node.getTextContent());
			 
			 if(node.hasAttributes()){
				 NamedNodeMap  nodeMap = node.getAttributes();
				 
				 for(int j = 0; j < nodeMap.getLength() ; j++){
					
					 Node  nodenew = nodeMap.item(j);
					 
					System.out.println("node name "+nodenew.getNodeName());
					System.out.println("node value "+nodenew.getNodeValue());
				 }
			 }
			 if(node.hasChildNodes()){
				 printNode(node.getChildNodes());
			 }
		 }
	
	 }
	 
 }

}


输出结果如下:

Root  element: bookstore
------------------------
node name: bookstore
node value: 
  
    Everyday Italian
    Giada De Laurentiis
    2005
    30.00
  
  
    Harry Potter
    J K. Rowling
    2005
    29.99
  
  
    XQuery Kick Start
    James McGovern
    2003
    49.99
  
  
    Learning XML
    Erik T. Ray
    2003
    39.95
  

------------------------
node name: book
node value: 
    Everyday Italian
    Giada De Laurentiis
    2005
    30.00
  
node name category
node value cooking
------------------------
node name: title
node value: Everyday Italian
node name lang
node value en
------------------------
node name: author
node value: Giada De Laurentiis
------------------------
node name: year
node value: 2005
------------------------
node name: price
node value: 30.00
------------------------
node name: book
node value: 
    Harry Potter
    J K. Rowling
    2005
    29.99
  
node name category
node value children
------------------------
node name: title
node value: Harry Potter
node name lang
node value en
------------------------
node name: author
node value: J K. Rowling
------------------------
node name: year
node value: 2005
------------------------
node name: price
node value: 29.99
------------------------
node name: book
node value: 
    XQuery Kick Start
    James McGovern
    2003
    49.99
  
node name category
node value web
------------------------
node name: title
node value: XQuery Kick Start
node name lang
node value en
------------------------
node name: author
node value: James McGovern
------------------------
node name: year
node value: 2003
------------------------
node name: price
node value: 49.99
------------------------
node name: book
node value: 
    Learning XML
    Erik T. Ray
    2003
    39.95
  
node name category
node value web
node name cover
node value paperback
------------------------
node name: title
node value: Learning XML
node name lang
node value en
------------------------
node name: author
node value: Erik T. Ray
------------------------
node name: year
node value: 2003
------------------------
node name: price
node value: 39.95
------------------------


关于节点的问题:

 <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>

对于 book应用:doc.getChildNodes() 得到一个NodeList其中NodeList的长度为9

9个节点分别如下:

title节点

lang节点  

Everyday节点

 author节点 

Giada De Laurentiis节点

 year节点

 2005节点

 price节点

 30.00节点



文章评论

软件开发程序错误异常ExceptionCopyright © 2009-2015 MyException 版权所有