Using java in http connection

Maybe someone can help me with some java stuff.
I'm using a java application to connect to an HTTPS site. My OS is linux.
Initially i have no certificate of the server, e.q.( a machine with IP
192.168.1.2).
I want to connect to that IP using https and acquire its certificate,
and just like
web browser, I need to prompt a dialog to either accept or cancel the
certificate.

Do you have any idea how to do?

You can try this, http://hc.apache.org/httpclient-3.x/sslguide.html

Using predefine protocol :
org.apache.commons.httpclient.contrib.ssl.EasySSLProtocolSocketFactory