Dynamic XML creation in Java

Question

I am trying to dynamically y create an XML file in Java to display a timetable. I have created a DTD for my XML file and I have an XSL file I would like to use to transform the XML. I don't know exactly how to continue.

What I've tried so far is onClick of some button a Servlet is called which generates the string of the content of the XML file (inserting the dynamic parts of the XML into the String. I now have a String containing the content of the XML file. I would now like to transform the XML file using an XSL file i have on my server and display the result in the page which has called the Servlet (doing this via AJAX).

I'm not sure if I'm in the direction, perhaps I shouldn't even create the XML code in String form from the beginning. So my question is, how do I continue from here? how do I transform the XML string, using the XSL file, and send it as a response to the AJAX call so I can plant the generated code into the page? Or if this is not the way to do it, how do I create a dynamic XML file in a different way producing the same result?

Answer 1

You can use JAXP for this. It's part of standard Java SE API.

StringReader xmlInput = new StringReader(xmlStringWhichYouHaveCreated);
InputStream xslInput = getServletContext().getResourceAsStream("file.xsl"); // Or wherever it is. As long as you've it as an InputStream, it's fine.

Source xmlSource = new StreamSource(xmlInput);
Source xslSource = new StreamSource(xslInput);
Result xmlResult = new StreamResult(response.getOutputStream()); // XML result will be written to HTTP response.

Transformer transformer = TransformerFactory.newInstance().newTransformer(xslSource);
transformer.transform(xmlSource, xmlResult);

Answer 2

Depending on how complicated and large your XML is going to be I would suggest two options. For small, simple structures Java's DOM implementation (Document) will suffice.

If your XML is more elaborate I would look into JAXB. The benefit there is that there are tools that automatically create Java classes from an XML schema (XSD). So you'd have to transform your DTD into an XSD first, but that shouldn't be a problem. You end up with plain data transfer objects (plain objects with getters/setters for the values of the corresponding XML elements) and parsing/encoding plus setting namespaces correctly is done for you. It's quite convenient but can also be a bit of an overkill for simple XML structures.

In both cases, you will end up with a Document instance that you can finally transform using JAXP.