Question

I have a XmlDocument in java, created with the Weblogic XmlDocument parser.

I want to replace the content of a tag in this XMLDocument with my own data, or insert the tag if it isn’t there.

<customdata>    <tag1 />    <tag2>mfkdslmlfkm</tag2>    <location />    <tag3 /> </customdata> 

For example I want to insert a URL in the location tag:

<location>http://something</location> 

but otherwise leave the XML as is.

Currently I use a XMLCursor:

    XmlObject xmlobj = XmlObject.Factory.parse(a.getCustomData(), options);     XmlCursor xmlcur = xmlobj.newCursor();      while (xmlcur.hasNextToken()) {       boolean found = false;       if (xmlcur.isStart() && 'schema-location'.equals(xmlcur.getName().toString())) {         xmlcur.setTextValue('http://replaced');         System.out.println('replaced');         found = true;       } else if (xmlcur.isStart() && 'customdata'.equals(xmlcur.getName().toString())) {         xmlcur.push();       } else if (xmlcur.isEnddoc()) {         if (!found) {           xmlcur.pop();           xmlcur.toEndToken();           xmlcur.insertElementWithText('schema-location', 'http://inserted');           System.out.println('inserted');         }        }       xmlcur.toNextToken();     } 

I tried to find a ‘quick’ xquery way to do this since the XmlDocument has an execQuery method, but didn’t find it very easy.

Do anyone have a better way than this? It seems a bit elaborate.

Answer 1

How about an XPath based approach? I like this approach as the logic is super-easy to understand. The code is pretty much self-documenting.

If your xml document is available to you as an org.w3c.dom.Document object (as most parsers return), then you could do something like the following:

// get the list of customdata nodes NodeList customDataNodeSet = findNodes(document, '//customdata' );  for (int i=0 ; i < customDataNodeSet.getLength() ; i++) {   Node customDataNode = customDataNodeSet.item( i );    // get the location nodes (if any) within this one customdata node   NodeList locationNodeSet = findNodes(customDataNode, 'location' );    if (locationNodeSet.getLength() > 0) {     // replace     locationNodeSet.item( 0 ).setTextContent( 'http://stackoverflow.com/' );   }   else {     // insert     Element newLocationNode = document.createElement( 'location' );     newLocationNode.setTextContent('http://stackoverflow.com/' );     customDataNode.appendChild( newLocationNode );   } } 

And here’s the helper method findNodes that does the XPath search.

private NodeList findNodes( Object obj, String xPathString )   throws XPathExpressionException {    XPath xPath = XPathFactory.newInstance().newXPath();   XPathExpression expression = xPath.compile( xPathString );   return (NodeList) expression.evaluate( obj, XPathConstants.NODESET ); }