java中的xml操作
（1）使用java读取XML文件： DOM解析XML
XML样例如下：（language.xml）
xml version="1.0"encoding="UTF-8"?>
<Languages cat="it">
<lan id="1">
<name>javaname>
<ide>eclipseide>
lan>
<lan id="2">
<name>swiftname>
<ide>Xcodeide>
lan>
<lan id="3">
<name>C#name>
<ide>Visual Studioide>
lan>
Languages>
解析方式如下：
//DOM解析XML（用try catch ）
DocumentBuilderFactoryfactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse("language.xml");
Element root = (Element) doc.getDocumentElement();
System.out.println("cat = "+root.getAttribute("cat"));
NodeList list = root.getElementsByTagName("lan");
for (int i =0;i<list.getLength();i++)
{
Element lan = (Element)list.item(i);
System.out.println("-----------------");
System.out.println("id="+lan.getAttribute("id"));·
// Element name = (Element)lan.getElementsByTagName("name").item(0);
// System.out.println(name.getTextContent());
// Element ide = (Element)lan.getElementsByTagName("ide").item(0);
// System.out.println(ide.getTextContent());
NodeList cList = lan.getChildNodes();
for(int j = 0;j<=cList.getLength();j++){
Node e = cList.item(j);
if(e instanceof Element) {
System.out.println(e.getNodeName()+"="+e.getTextContent());
}
}
}
运行结果：
cat = it
-----------------
id=1
name=java
ide=eclipse
-----------------
id=2
name=swift
ide=Xcode
-----------------
id=3
name=C#
ide=Visual Studio
（2）使用java创建XML数据：
public static void main(String[] args) {
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.newDocument();
Element root = document.createElement("language");
root.setAttribute("cat", "it");
Element lan1 = document.createElement("lan");
lan1.setAttribute("id", "1");
Element name1 = document.createElement("name");
name1.setTextContent("java");
Element ide1 = document.createElement("ide");
ide1.setTextContent("eclipse");
Element lan2 = document.createElement("lan");
lan2.setAttribute("id", "2");
Element name2 = document.createElement("name");
name2.setTextContent("swift");
Element ide2 = document.createElement("ide");
ide2.setTextContent("Xcode");
Element lan3 = document.createElement("lan");
lan3.setAttribute("id", "3");
Element name3 = document.createElement("name");
name3.setTextContent("C#");
Element ide3 = document.createElement("ide");
ide3.setTextContent("visualStudio");
lan1.appendChild(name1);
lan1.appendChild(ide1);
root.appendChild(lan1);
lan2.appendChild(name2);
lan2.appendChild(ide2);
root.appendChild(lan2);
lan3.appendChild(name3);
lan3.appendChild(ide3);
root.appendChild(lan3);
document.appendChild(root) ;
//---------将当前文档转化成字符串显示----------------------
try {
TransformerFactory transformerFactory =TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
StringWriter writer = new StringWriter();
//转化输入输出流
transformer.transform(new DOMSource(document), new StreamResult(writer));
System.out.println(writer.toString());
//文件
transformer.transform(new DOMSource(document), new StreamResult(new File("111.xml")));
} catch (TransformerConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TransformerException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (ParserConfigurationException e) {
e.printStackTrace();
}
}
运行后，刷新项目（F5）就会发现项目中创建了111.xml文件，在控制台也有输出。创建好的文件没有格式，全选内容，用ctrl+I快捷键格式化数据，就可以看到有层次感的xml文件。
如下所示：
xml version="1.0"encoding="UTF-8" standalone="no"?>
<language cat="it">
<lan id="1">
<name>javaname>
<ide>eclipseide>
lan>
<lan id="2">
<name>swiftname>
<ide>Xcodeide>
lan>
<lan id="3">
<name>C#name>
<ide>visualStudioide>
lan>
language>
（3）使用DOM4J操作xml数据:
工具下载网址：www.dom4j.org/dom4j-1.6.1/
在项目中新建一个lib文件夹。将dom4j下载并解压，解压后的dom4j-1.6.jar拷贝在工程目录Lib文件夹下。在main()中：
String xmlString = “
Document doc=DocumentHelper.pareseText(xmlString);
System.out.println(document.asXML));
若需要了解其他的用法，打开解压后的/doc/index就可以查看完整的操作说明。