Read up on JCE to see if there is a  method to do this for you.
see http://mindprod.com/jgloss/jce.html

If the public cert itself is exchanged under some circumstances in an
ordinary browser interaction try getting a copy of Ethereal (see
http://mindprod.com/jgloss/sniffer.html)

and watch the packets going back and forth. Then  mimic that with a
raw socket.

--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

On Jun 28, 2:12 pm, genk...@gmail.com wrote:

Just guessing: (let me know if this helps)

import java.net.*;
import java.io.*;

import javax.net.ssl.HttpsURLConnection;
import javax.security.cert.Certificate;

public class SSLGetCertificateFromWebPager {
   public static void main(String[] args) throws Exception {
       URL site = new URL("https://mail.google.com/mail/");
       HttpsURLConnection conn = (HttpsURLConnection)
site.openConnection();
       conn.setDoOutput(true);
       InputStream istream = conn.getInputStream();
       java.security.cert.Certificate[] aCerts =
conn.getServerCertificates();
       System.out.println( "The certificate is " );
       System.out.println( aCerts[0].toString() );
       System.out.println( "The certificate encoding is " +
aCerts[0].getType() );
       byte[] data = aCerts[0].getEncoded();
       File file = new File( "gmail_downloaded.cer" ); // DER
encoding for instance
       DataOutputStream dos = new DataOutputStream( new
FileOutputStream( file ) );
       dos.write( data );
       dos.close();
       BufferedReader br = new BufferedReader(
                               new InputStreamReader(
                               istream ));
       String line;

       while ((line = br.readLine()) != null)
           System.out.println(line);
       br.close();
   }
}

Best,
TimJowers