java mail gmail

我想通过谷歌的smtp服务器在我的java程序中发送邮件,但它似乎停留在发送邮件.有人可以告诉我为什么请？

这是发送邮件的功能：

     public void sendMail(){
            String from = "xxx@gmail.com";
    String to = "xxx@hotmail.com";
    String subject = "Test";
    String message = "A test message";

    SendMail sendMail = new SendMail(from,to,subject,message);
    sendMail.send();
}

这是班级

public class SendMail {
private String from;
private String to;
private String subject;
private String text;

public SendMail(String from,String to,String subject,String text){
    this.from = from;
    this.to = to;
    this.subject = subject;
    this.text = text;
}

public void send(){

    Properties props = new Properties();
    props.put("mail.smtp.host","smtp.gmail.com");
    props.put("mail.smtp.auth","true");
    props.setProperty( "mail.smtp.port","587" );
    props.put("mail.smtp.starttls.enable","true");
    Session session = Session.getDefaultInstance(props);

    new javax.mail.Authenticator() {
    protected PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication(from,"MyPasswordGoesHere");
    }
      };

  try {
    MimeMessage message = new MimeMessage(session);
    message.setFrom(new InternetAddress(from));
    message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
    message.setSubject(subject);
    message.setText(text);

    Transport.send(message);
    System.out.println("message sent successfully");
    } catch (MessagingException e) {
    throw new RuntimeException(e);
     }
      }
        }

提前致谢！