Get the SSLSession from your SSLSocket on your client and use its getProtocol() method.
Oracle JRE/OpenJDK 6 supports SSLv3 and TLS 1.0. You would need at least the IBM JRE 6/7 or Oracle JRE/OpenJDK 7 to get support for TLS 1.1 and TLS 1.2. (This is also related to the available cipher suites, as mentioned in this question.)
