如何將屬性添加到Java中的現有XML元素？

Question

我想使用Java在XML中追加一個屬性。例如：

<employee> 
<details name="Jai" age="25"/> 
<details name="kishore" age="30"/> 
</employee> 

它要添加weight到它（假設它被計算並且然後響應所附）。我如何將它附加到所有項目？

<details name="Jai" age="25" weight="55"/> 

Answer 1

import org.w3c.dom.*; 
import java.io.*; 
import javax.xml.parsers.*; 
import javax.xml.transform.*; 
import javax.xml.transform.dom.*; 
import javax.xml.transform.stream.*; 

public class AddAndPrint { 

    public static void main(String[] args) {  
    DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance(); 
    DocumentBuilder docBuilder = docFactory.newDocumentBuilder(); 
    Document doc = docBuilder.parse("/path/to/file.xml"); 
    NodeList employees = document.getElementsByTagName("employee"); 
    for (Node employee : employees) { 
     for (Node child : employee.getChildNodes() { 
     if ("details".equals(child.getNodeName()) child.setAttribute("weight", "150"); 
     } 
    } 

    try { 
     Source source = new DOMSource(doc); 
     StringWriter stringWriter = new StringWriter(); 
     Result result = new StreamResult(stringWriter); 
     TransformerFactory factory = TransformerFactory.newInstance(); 
     Transformer transformer = factory.newTransformer(); 
     transformer.transform(source, result); 
     System.out.println(stringWriter.getBuffer().toString()); 
    } catch (TransformerConfigurationException e) { 
     e.printStackTrace(); 
    } catch (TransformerException e) { 
     e.printStackTrace(); 
    } 
    } 
} 

Answer 2

這裏是一個快速的解決方案基於JDOM：

public static void main(String[] args) throws JDOMException, IOException { 
    File xmlFile = new File("employee.xml"); 
    SAXBuilder builder = new SAXBuilder(); 
    Document build = builder.build(xmlFile);   
    XPath details = XPath.newInstance("//details"); 
    List<Element> detailsNodes = details.selectNodes(build); 
    for (Element detailsNode:detailsNodes) { 
     detailsNode.setAttribute("weight", "70"); // static weight for demonstration 
    } 
    XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat()); 
    outputter.output(build, System.out); 
} 

首先，我們建立了一個文件（SAXBuilder），接下來我們創建一個細節節點的XPath表達式，那麼我們迭代通過該表達式的元素並添加weight屬性。

最後兩行只是驗證它的白魔法:-)