EmailUtility.java

package com.occamlab.te.web;

import java.util.Date;
import java.util.Properties;
import java.util.Random;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class EmailUtility {

	public static void sendEmail(String host, String portNo, final String userName, final String pwd, String toAddress,
			String subject, String message) throws AddressException, MessagingException {

		Properties properties = new Properties();
		properties.put("mail.smtp.host", host);
		properties.put("mail.smtp.port", portNo);
		properties.put("mail.smtp.auth", "true");
		properties.put("mail.smtp.starttls.enable", "true");
		// see https://bugs.openjdk.org/browse/JDK-8202343
		properties.put("mail.smtp.ssl.protocols", "TLSv1.2");

		Authenticator auth = new Authenticator() {
			public PasswordAuthentication getPasswordAuthentication() {
				return new PasswordAuthentication(userName, pwd);
			}
		};

		Session session = Session.getInstance(properties, auth);
		Message msg = new MimeMessage(session);
		try {
			msg.setFrom(new InternetAddress(userName));
			InternetAddress[] toAddresses = { new InternetAddress(toAddress) };
			msg.setRecipients(Message.RecipientType.TO, toAddresses);
			msg.setSubject(subject);
			msg.setSentDate(new Date());
			msg.setContent(message, "text/html; charset=utf-8");

			Transport.send(msg);
		}
		catch (Exception e) {
			throw new RuntimeException("Failed send mail : " + e.getMessage());
		}
	}

	public static String getRandomNumberString() {
		Random randomNo = new Random();
		int number = randomNo.nextInt(999999);
		return String.format("%06d", number);
	}

}