Please help, Urgent ! creation of xml from servlet

Question

Hi,
I have to write a servlet that takes user input from a html form and creates a xml file from those input parameters and transform that xml file into html form using xsl program. Whenever the user adds new values to the form this newly generated xml file should overwrite the previous xml file content.
Can anybody please tell me how to create a xml file from user input in servlet so that I can pass it to a transformer object.
Thanks in advance!

Answer 1

why write out the XML, it seems to be only a temporary file?
Doing as you suggest is extremely risky for when several requests come in at the same time you can never be sure that the file contains the data that you just wrote to it.
Better to keep the XML all in memory.
For the XML creation, look no further than DOM. Most XML parsers provide excellent DOM support, I'll be using Xerces 2 here as that's what I'm most familiar with.
Document doc = new DocumentImpl();
Element root = doc.createElement("mydoc");
* fill in the XML
Element elem = doc.createElement("focuscontrol");
elem.appendChild(doc.createTextNode("alert('loaded')"));
root.appendChild(elem);
elem = doc.createElement("data");
elem.appendChild(doc.createTextNode("Hello World!"));
root.appendChild(elem);     
doc.appendChild(root);     creates an XML Document object like this:
<?xml version="1.0"?>
<mydoc>
  <focuscontrol>alert('loaded')</focuscontrol>
  <data>Hello World!</data>
</mydoc>This XML Document object can be easily passed to an XSLT processor to turn it into HTML.
String path = getServletContext().getRealPath("/WEB-INF/xsl/");
TransformerFactory tFactory = TransformerFactory.newInstance();
Source xslSource = new StreamSource(new File(path, "myxslfile.xsl"));
Source xmlSource = new DOMSource(doc);     
t.transform(xmlSource, new StreamResult(out));where out is the PrintWriter for the servlet and your XSL file is stored in yourwebapp/WEB-INF/xsl (thus out of sight of prying eyes).
I leave it up to you to find an encoding of your request parameters into the generated XML that you like.