Kevin Kevin - 1 year ago 109
Java Question

XML Node to String in Java

I came across this piece of Java function to convert an XML node to a Java String representation:

private String nodeToString(Node node) {
StringWriter sw = new StringWriter();
try {
Transformer t = TransformerFactory.newInstance().newTransformer();
t.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
t.setOutputProperty(OutputKeys.INDENT, "yes");
t.transform(new DOMSource(node), new StreamResult(sw));
} catch (TransformerException te) {
System.out.println("nodeToString Transformer Exception");
return sw.toString();

It looks straightforward in that it wants the output string doesn't have any XML declaration and it must contain indentation.

But I wonder how the actual output should be, suppose I have an XML node:

<p><media type="audio" id="au008093" rights="wbowned">
<title>Bee buzz</title>
</media>Most other kinds of bees live alone instead of in a colony. These bees make
tunnels in wood or in the ground. The queen makes her own nest.</p>

Could I assume the resulting String after applying the above transformation is:

"media type="audio" id="au008093" rights="wbowned" title Bee buzz title /media"

I want to test it myself, but I have no idea on how to represent this XML node in the way this function actually wants.

I am bit confused, and thanks in advance for the generous help.

Answer Source

You have an XML respesentation in a DOM tree.
For example you have opened an XML file and you have passed it in the DOM parser.
As a result a DOM tree in memory with your XML is created.
Now you can only access the XML info via traversal of the DOM tree.
If you need though, a String representation of the XML info of the DOM tree you use a transformation.
This happens since it is not possible to get the String representation directly from a DOM tree.
So if for example as Node node you pass in nodeToString is the root element of the XML doc then the result is a String containing the original XML data.
The tags will still be there. I.e. you will have a valid XML representation. Only this time will be in a String variable.

For example:

  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
  DocumentBuilder parser = factory.newDocumentBuilder();
  Document xmlDoc = parser.parse(file);//file has the xml
  String xml = nodeToString(xmlDoc.getDocumentElement());//pass in the root
  //xml has the xml info. E.g no xml declaration. Add it
  xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?> + xml;//bad to append this way...
  System.out.println("XML is:"+xml);

DISCLAIMER: Did not even attempt to compile code. Hopefully you understand what you have to do