<p>I want to consume a web service over https from a java client.
What steps will i need to take in order to do this?</p>

Really, there shouldn't much different from consuming a web service over HTTP. The big thing is that the process calling the web service will have to trust the server's SSL certificate. If the certificate was purchased from a well-known certificate-issuing authority, this usually isn't a problem. Otherwise, the client will want to either trust the root certificate, or the certificate associated with the server's fully qualified host name.