connect to Gmail Imap using javamail

import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Store;
public class Program {
    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        String host = "imap.gmail.com";
        int port = 993;
        String user = "xxxxx@gmail.com";
        String password = "xxxxx";
        String target_folder = "INBOX";
        Properties props = System.getProperties();
        Session sess = Session.getInstance(props, null);
//        sess.setDebug(true);
        Store st = sess.getStore("imaps");
        st.connect(host, port, user, password);
        Folder fol = st.getFolder(target_folder);
        if (fol.exists()) {
            for (Folder f : fol.list()) {
                System.out.println(f.getName());
            }
            fol.open(Folder.READ_ONLY);
            for (Message m : fol.getMessages()) {
                System.out.printf("%s - %d/n", m.getSubject(), m.getSize());
            }
            fol.close(false);
        } else {
            System.out.printf("%s is not exist.", target_folder);
        }
        st.close();
    }
}