For a recent project, I wrote a musicXML parser in java. The code is available on Bitbucket.
MusicXMLparserDH is a java musicXML parser that parses a musicXML file in Note objects with have properties such as pitch, accidental, duration, start time etc. It outputs an ArrayList that contains all of the Notes in sequence. A list of notes per time slice is also provided. The main time saver in using this library is that the note onsets are already calculated.