SMTP Java EE的连接错误

protected void doPost(HttpServletRequest request, HttpServletResponse response) 
        throws ServletException, IOException {



    response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter(); 

        Random rand = new Random();
        int num = rand.nextInt(900000) + 100000;
        String Password = Integer.toString(num);

        String Name = request.getParameter("name");
        String Email = request.getParameter("email");
        String UserType = request.getParameter("usertype");
        String strDOB = request.getParameter("dob");
        String Gender = request.getParameter("gender");

        java.sql.Date d;

        SimpleDateFormat sdf;
        sdf = new SimpleDateFormat("yyyy-MM-dd");
        java.util.Date d2 = null;

        try{
            d2 = sdf.parse(strDOB);
        } catch (ParseException e1) {
            e1.printStackTrace();
        }

        d = new java.sql.Date(d2.getTime());

        // Configuration for Email Sender



        DBAO dbao = null;
        Login login = null;


        try {
            Properties props = System.getProperties();
            String host = "smtp.gmail.com";
            String port = "465";
            String fromEmail = "lookeverybodysg@gmail.com";
            String username = "lookeverybodysg";
            String password = "catdog1234";

            props.put("mail.smtp.user", fromEmail);
            props.put("mail.smtp.host", host);
            props.put("mail.smtp.starttls.enable","true");
            props.put("mail.smtp.debug", "true");
            props.put("mail.smtp.auth", "true");
            props.put("mail.smtp.port", port);
            props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
            props.put("mail.smtp.socketFactory.port", port);
            props.put("mail.smtp.socketFactory.fallback", "false");


            Session mailSession = Session.getDefaultInstance(props, new javax.mail.Authenticator());
            mailSession.setDebug(true);

            Message mailMessage = new MimeMessage(mailSession);

            dbao = new DBAO();

                if (dbao.emailExists(Email)){
                    request.setAttribute("Name", Name);
                    request.setAttribute("Email", Email);
                    request.setAttribute("UserType", UserType);
                    request.setAttribute("strDOB", strDOB);
                    request.setAttribute("Gender", Gender);

                    response.setContentType("text/html");
                    out.println("<script type=\"text/javascript\">"); 
                    out.println("alert('The email you have used has already been regietered.');");
                    out.println("location='Login.jsp#signup';");
                    out.println("</script>"); 
                    return;
                }else{
                    login = new Login();
                    login.setName(Name);
                    login.setEmail(Email);
                    login.setPassword(Password);
                    login.setUserType(UserType);
                    login.setDOB(d);
                    login.setGender(Gender);

                    boolean isUserSaved = dbao.saveNewUser(login);

                if (isUserSaved){
                    mailMessage.setFrom(new InternetAddress("lookeverybodysg@gmail.com"));
                    mailMessage.setRecipient(Message.RecipientType.TO, new InternetAddress(Email));
                    mailMessage.setSubject("LookEveryBody Account");
                    mailMessage.setContent("Password :" + Password, "text/html");

                    Transport transport = mailSession.getTransport("smtps");
                    transport.connect (host, username, password);

                    transport.send(mailMessage);


                    response.setContentType("text/html");
                    out.println("<script type=\"text/javascript\">"); 
                    out.println("alert('Your accout has been successfully created, please go to your email to get your password.');");
                    out.println("location='Login.jsp';");
                    out.println("</script>"); 
                    return;
                }

            }

        }catch(Exception e)
        {
            e.printStackTrace();
        }
}

javax.mail.MessagingException：无法连接到SMTP主机：smtp.gmail.com，port：465;嵌套异常是：java.net.ConnectException：连接被拒绝：连接

我一直收到这个错误日志，所以我的学校网络阻塞或我的代码有问题吗？