We are also looking for some way to convert html files with complex javascript to pdf.
The javasript in our files contains document.write and DOM manipulation.

We have tried using a combination of HtmlUnit to parse the files and Flying Saucer to render to pdf but the results are not satisfactory enough. It works, but in our case the pdf is not close enough to what the user wants.

If you want to try this out, here is a code snippet to convert a local html file to pdf.

URL url = new File(test.html).toURI().toURL();

WebClient webClient = new WebClient(); 

HtmlPage page = webClient.getPage(url);



OutputStream os = null;

try{

   os = new FileOutputStream(test.pdf);



   ITextRenderer renderer = new ITextRenderer();

   renderer.setDocument(page,url.toString());

   renderer.layout();

   renderer.createPDF(os);

} finally{

   if(os != null) os.close();

}