java读取解析xml文件实例

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：

 
 
 Giada De Laurentiis
 2005
 30.00
 
 
 
 J K. Rowling
 2005
 29.99
 
 
 
 James McGovern
 2003
 49.99
 
 
 
 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: 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 
 

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：

 
 
 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

PS：这里再为大家提供几款关于xml操作的在线工具供大家参考使用：

在线XML/JSON互相转换工具：
http://tools.jb51.net/code/xmljson

在线格式化XML/在线压缩XML：
http://tools.jb51.net/code/xmlformat

XML在线压缩/格式化工具：
http://tools.jb51.net/code/xml_format_compress