关于JAVA邮件传输对象的快速说明

Question

Am trying to implement a mailing module using Java mail API. So far what I have done is

session = Session.getInstance(serverDetails,
                new javax.mail.Authenticator() {
                    protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication(userName, password);
                    }
                });
try {
            transport = session.getTransport("smtp");
            transport.connect();
        } catch (MessagingException e) {
            System.out.println(e.getMessage());
        }
MimeMessage message = new MimeMessage(session);
        // set the mail sender address
        message.setFrom(new InternetAddress(userName));
        // set the recipient addresses
        message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse(toAddr));
        // set subject of the mail
        message.setSubject(subject);
        // Set the body of the message
        message.setText(body);
        // Create a SMTP message object by which we will be able to get the
        // delivery status
        SMTPMessage smtpMsg = new SMTPMessage(message);
        smtpMsg.setReturnOption(SMTPMessage.RETURN_HDRS);
        smtpMsg.setNotifyOptions(SMTPMessage.NOTIFY_SUCCESS
                | SMTPMessage.NOTIFY_FAILURE);
        // attach the listeners for the connection and transmission
        transport.addConnectionListener(this);
        transport.addTransportListener(this);
        // connect to the server and send the message
        try{
            transport.sendMessage(smtpMsg, smtpMsg.getAllRecipients());
        }catch(IllegalStateException e){
            e.printStackTrace();
        }

I am initialising transport only once and trying to send multiple mails in a loop(abve code doesn't shows the looping part). is it allowed? can I send multiple mails with single instance of trasport object?

I am getting the following error

  org.quartz.core.ErrorLogger schedulerError
    SEVERE: Job (group1.job1 threw an exception.
    org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.IllegalStateException: Not connected]
        at org.quartz.core.JobRunShell.run(JobRunShell.java:213)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:525)
    Caused by: java.lang.IllegalStateException: Not connected
        at com.sun.mail.smtp.SMTPTransport.checkConnected(SMTPTransport.java:2263)
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1075)
        at org.mail.MailSender.sendMailAction(MailSender.java:237)
        at org.mail.MailSender.sendMail(MailSender.java:100)
        at com.util.PopulateMailQueue.populateQueue(PopulateMailQueue.java:172)
        at org.mail.cronjob.CronJob.execute(CronJob.java:14)
        at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
        ... 1 more

Please help me pointing out the problem here.

Answer 1

Yes, you can send multiple mails in a loop after connecting and before closing the transport.

transport.connect();

for (int i = 0; i < count; i++) {

    //  Create your message
        transport.sendMessage(smtpMsg, smtpMsg.getAllRecipients());
    }

transport.close();

You received that error, maybe because you closed the transport before sending all the mails

Answer 2

Can you check your console logs? It might be that you are missing an exception. Because this:

....
   transport.connect();
} catch (MessagingException e) {
    System.out.println(e.getMessage());
}

only logs the problem to console and then continues on. If the connect fails, you wont even see it in your normal log.