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：
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
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解析结果：
Root element: bookstoreNode name: book----------------------------book category: cookingtitle name: Everyday Italianauthor name: Giada De Laurentiisyear :2005price : 30.00-------------------------Node name: book----------------------------book category: childrentitle name: Harry Potterauthor name: J K. Rowlingyear :2005price : 29.99-------------------------Node name: book----------------------------book category: webtitle name: XQuery Kick Startauthor name: James McGovernyear :2003price : 49.99-------------------------Node name: book----------------------------book category: webtitle name: Learning XMLauthor name: Erik T. Rayyear :2003price : 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输出结果如下：
Root element: bookstore------------------------node name: bookstorenode 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: booknode value: Everyday Italian Giada De Laurentiis 2005 30.00 node name categorynode value cooking------------------------node name: titlenode value: Everyday Italiannode name langnode value en------------------------node name: authornode value: Giada De Laurentiis------------------------node name: yearnode value: 2005------------------------node name: pricenode value: 30.00------------------------node name: booknode value: Harry Potter J K. Rowling 2005 29.99 node name categorynode value children------------------------node name: titlenode value: Harry Potternode name langnode value en------------------------node name: authornode value: J K. Rowling------------------------node name: yearnode value: 2005------------------------node name: pricenode value: 29.99------------------------node name: booknode value: XQuery Kick Start James McGovern 2003 49.99 node name categorynode value web------------------------node name: titlenode value: XQuery Kick Startnode name langnode value en------------------------node name: authornode value: James McGovern------------------------node name: yearnode value: 2003------------------------node name: pricenode value: 49.99------------------------node name: booknode value: Learning XML Erik T. Ray 2003 39.95 node name categorynode value webnode name covernode value paperback------------------------node name: titlenode value: Learning XMLnode name langnode value en------------------------node name: authornode value: Erik T. Ray------------------------node name: yearnode value: 2003------------------------node name: pricenode value: 39.95------------------------
关于节点的问题：
Everyday Italian Giada De Laurentiis 2005 30.00
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
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