You can produce a HTML File with an EncodedPolyline from a GPX File using the command:

java -jar PolylineEncoder.jar Filename

SampleFiles are in GPS-Testfiles

try: java -jar PolylineEncoder.jar GPS-Testfiles/MtMitchell.gpx

The GPX Parser is written in Groovy, the PolylineEncoder can be used seperatly and without the Groovy Parser stuff.