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：

<?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: 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：

<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

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