Test host certificate

CertTest.java

import java.io.IOException;
import java.net.UnknownHostException;
import java.security.cert.Certificate;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
 
public class CertTest {
    public static void main(String[] args) throws UnknownHostException, IOException {
        int port = 443;
        String hostname = "google.es";
 
        System.setProperty("javax.net.debug", "ssl");
        SSLSocketFactory factory = HttpsURLConnection.getDefaultSSLSocketFactory();
        SSLSocket socket = (SSLSocket) factory.createSocket(hostname, port);
 
        socket.startHandshake();
 
        Certificate[] serverCerts = socket.getSession().getPeerCertificates();
        System.out.println("number of found certificates: " + serverCerts.length);
        for (Certificate certificate : serverCerts) {
            System.out.println(certificate.getPublicKey());
            System.out.println(certificate);
        }
 
        socket.close();
    }
}