Don't understand the question...
Do you mean:
- is it possible to CREATE a webservice in Java mode? (but why would you?)
- is it possible to CONSUME a webservice in Java mode? (but in that case, are you talking soap or rest webservice)... Now for rest, you only need httprequest, and that is supported. For soap, the documentation states "Using a Webservice in a Java project requires a Java virtual machine (JRE) in version 6 (or 6.1) or later."