I was going to point you to the Maven repository at http://mirrors.ibiblio.org/pub/mirrors/maven2/xdoclet/xdoclet/. but version 1.2.1 is not there. They have 1.2 and 1.2.3, but not 1.2.1. I would try downloading 1.2.3 and see if that works.
Thank you for your reply.
i face the same issue,
the problem is that the file "xdoclet-1.2.1.jar" is not in the lib directory.
the solution is : just download the file "xdoclet-1.2.1.jar" from somewhere and add this file to the lib directory, i found it works.