I was writing some Java codes to process some XML data and encountered an annoying problem which took me a while to fix. I want to put this down here in my blog in case I forget.
I'm using JAXP API to parse my XML to DOM, I then need to extract a sub-element and serialize it back to XML as string. It is working fine when run as a standalone application, but when I used the code in a servlet deployed in Tomcat I got "Provider org.apache.xalan.processor.TransformerFactoryImpl not found" exception. Initially I thought that maybe I'm missing my xalan.jar but then after googling I find a suggestion to set the system property to use another TransformerFactory implementation:
System.setProperty("javax.xml.transform.TransformerFactory",
"com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl");
Oh if any people out there are wondering how to get rid of the XML declaration header:
when serializing to XML, just set the output property.
DOMSource domSource = new DOMSource(xmldom);
StreamResult streamResult = new StreamResult(System.out); // print xml to stdout
TransformerFactory tf = TransformerFactory.newInstance();
Transformer serializer = tf.newTransformer();
serializer.setOutputProperty(javax.xml.transform.OutputKeys.OMIT_XML_DECLARATION, "yes");
serializer.transform(domSource, streamResult);
