How do I append a node to an existing XML file in java

Question

public static void addALLToXML(Collection<Server> svr) throws IOException,       ParserConfigurationException, TransformerException {     DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory         .newInstance();     DocumentBuilder documentBuilder = documentBuilderFactory         .newDocumentBuilder();     Document document = documentBuilder.newDocument();      // Root Element     Element rootElement = document.createElement("Servers");     document.appendChild(rootElement);      for (Server i : svr)     {         // server elements         Element server = document.createElement("server");         rootElement.appendChild(server);          Element name = document.createElement("name");         name.appendChild(document.createTextNode(i.getName()));         server.appendChild(name);          Element port = document.createElement("port");         port.appendChild(document.createTextNode(Integer.toString(i.getPort())));         server.appendChild(port);     }      TransformerFactory transformerFactory = TransformerFactory.newInstance();     Transformer transformer = transformerFactory.newTransformer();     DOMSource source = new DOMSource(document);      StreamResult result = new StreamResult("/home/user/server.xml");     transformer.transform(source, result); } 

This is the function I need help with:

public static void addNodeToXML(String nameIn, String portIn)       throws ParserConfigurationException, SAXException, IOException {     DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory             .newInstance();     DocumentBuilder documentBuilder = documentBuilderFactory             .newDocumentBuilder();      /* parse existing file to DOM */     Document document = documentBuilder             .parse(new File("/home/user/server.xml"));      // Root Element     Element rootElement = document.createElement("Servers");     document.appendChild(rootElement);      // server elements     Element server = document.createElement("server");     rootElement.appendChild(server);      Element name = document.createElement("name");     name.appendChild(document.createTextNode(nameIn));     server.appendChild(name);      Element port = document.createElement("port");     port.appendChild(document.createTextNode(portIn));     server.appendChild(port); } 

Original:

<Servers>  <server>   <name>something</name>   <port>port</port>  </server>  </Servers> 

Wanted:

<Servers>    <server>    <name>something</name>    <port>port</port>   </server>   <server>    <name>something</name>    <port>port</port>   </server> <Servers> 

Answer 1

The following complete example will read an existing server.xml file from the current directory, append a new Server and re-write the file to server.xml. It does not work without an existing .xml file, so you will need to modify the code to handle that case.

import java.util.*; import javax.xml.transform.*; import javax.xml.transform.stream.*; import javax.xml.transform.dom.*; import org.w3c.dom.*; import javax.xml.parsers.*;  public class AddXmlNode {     public static void main(String[] args) throws Exception {          DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();         DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();         Document document = documentBuilder.parse("server.xml");         Element root = document.getDocumentElement();          Collection<Server> servers = new ArrayList<Server>();         servers.add(new Server());          for (Server server : servers) {             // server elements             Element newServer = document.createElement("server");              Element name = document.createElement("name");             name.appendChild(document.createTextNode(server.getName()));             newServer.appendChild(name);              Element port = document.createElement("port");             port.appendChild(document.createTextNode(Integer.toString(server.getPort())));             newServer.appendChild(port);              root.appendChild(newServer);         }          DOMSource source = new DOMSource(document);          TransformerFactory transformerFactory = TransformerFactory.newInstance();         Transformer transformer = transformerFactory.newTransformer();         StreamResult result = new StreamResult("server.xml");         transformer.transform(source, result);     }      public static class Server {         public String getName() { return "foo"; }         public Integer getPort() { return 12345; }     } } 

Example server.xml file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Servers>   <server>     <name>something</name>     <port>port</port>   </server> </Servers> 

The main change to your code is not creating a new "root" element. The above example just uses the current root node from the existing server.xml and then just appends a new Server element and re-writes the file.