XML-RPC can be used with Python, Java, Perl, PHP, C, C++, Ruby, Microsoft’s .NET and many other programming languages. Implementations are widely available for platforms such as Unix, Linux, Windows and the Macintosh.
You can download the xml-rpc library from apache, and test the following code to do the login, create, write read, search, I will test and put the correct syntax for the rest of the service like wizard workflow and report. currently i have tested this library for the common and object service only.
Login to OpenERP using Java XML-RPC
Code for Login : http://bpaste.net/show/tG1FZrl18FdL2GRUQmAj/
Code for Create Record : http://bpaste.net/show/pJ6SCtfunRqoFmdmUOEf/