java中的xml操作
（1）使用java讀取XML檔案： DOM解析XML
XML樣例如下：（language.xml）
<?xml version="1.0"encoding="UTF-8"?>
<Languages cat="it">
<lan id="1">
<name>java</name>
<ide>eclipse</ide>
</lan>
<lan id="2">
<name>swift</name>
<ide>Xcode
</lan>
<lan id="3">
<name>C#</name>
<ide>Visual Studio</ide>
</lan>
</Languages>
解析方式如下：
//DOM解析XML（用try catch ）
DocumentBuilderFactoryfactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory
Document doc = builder.parse("language.xml");
Element root = (Element) doc.getDocumentElement();
System.out.println("cat = "+root.getAttribute("cat"));
NodeList list = root.getElementsByTagName("lan");
for
{
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());
}
}
}
執行結果：
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建立XML資料：
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) ;
//---------將當前文件轉化成字串顯示----------------------
try {
TransformerFactory transformerFactory =TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
StringWriter writer = new StringWriter();
//轉化輸入輸出流
transformer.transform(new DOMSource(document), new StreamResult(writer));
System.out.println(writer.toString());
//檔案
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();
}
}
執行後，重新整理專案（F5）就會發現專案中建立了111.xml檔案，在控制檯也有輸出。建立好的檔案沒有格式，全選內容，用ctrl+I快捷鍵格式化資料，就可以看到有層次感的xml檔案。
如下所示：
<?xml version="1.0"encoding="UTF-8" standalone="no"?>
<language cat="it">
<lan id="1">
<name>java</name>
<ide>eclipse</ide>
</lan>
<lan id="2">
<name>swift</name>
<ide>Xcode</ide>
</lan>
<lan id="3">
<name>C#</name>
<ide>visualStudio</ide>
</lan>
</language>
（3）使用DOM4J操作xml資料:
在專案中新建一個lib資料夾。將dom4j下載並解壓，解壓後的dom4j-1.6.jar拷貝在工程目錄Lib資料夾下。在main()中：
String xmlString = “ <lan><name>java</name><ide>eclipse</ide></lan>”
Document doc=DocumentHelper.pareseText(xmlString);
System.out.println(document.asXML));
若需要了解其他的用法，開啟解壓後的/doc/index就可以檢視完整的操作說明。