gistfile1.java

import org.apache.commons.lang.StringUtils;

import javax.mail.*;
import javax.mail.internet.*;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

public class SendGridExample {
    private static final String SMTP_HOST_NAME = "smtp.sendgrid.net";
    private static final String SMTP_AUTH_USER = "USERNAME-NOT-EMAIL";
    private static final String SMTP_AUTH_PWD = "***PASSWORD***";
    private static final String TEXT_HTML = "text/html";

    private static String PORT = "465";
    private static String STARTTLS = "true";
    private static String AUTH = "true";
    private static String SOCKET_FACTORY = "javax.net.ssl.SSLSocketFactory";

    private boolean debug = false;

    public static void main(String[] args) throws EmailException {
        final SendGridExample example = new SendGridExample();
        HashMap<String, String> map = new HashMap<String, String>();
        map.put("X-MyHeader", "blabla");
        example.send("[email protected]", "[email protected]", "subject", "text", "<b>html</b>", map);
    }

    public SendGridExample() {
    }

    public SendGridExample(boolean debug) {
        this.debug = debug;
    }

    public void send(String to, String subject, String text) throws EmailException {
        send(to, null, subject, text, null, new HashMap<String, String>());
    }

    public void send(
            String to, String subject, String text, String html) throws EmailException {
        send(to, null, subject, text, html, new HashMap<String, String>());
    }

    public void send(
            String to, String from, String subject, String text, String html,
            HashMap<String, String> headers) throws EmailException {

        Session mailSession = getMailSession();
        MimeMessage message = new MimeMessage(mailSession);

        try {
            Multipart multipart = new MimeMultipart("alternative");

            if (StringUtils.isNotBlank(text)) {
                BodyPart textPart = new MimeBodyPart();
                textPart.setText(text + "\n");
                multipart.addBodyPart(textPart);
            }

            if (StringUtils.isNotBlank(html)) {
                BodyPart htmlPart = new MimeBodyPart();
                htmlPart.setContent(html, TEXT_HTML);
                multipart.addBodyPart(htmlPart);
            }

            final InternetAddress fromAddress = from != null
                    ? new InternetAddress(from)
                    : new InternetAddress("[email protected]");

            if (!headers.isEmpty()) {
                for (Map.Entry<String, String> entry : headers.entrySet()) {
                    message.addHeader(entry.getKey(), entry.getValue());
                }
            }

            message.setSubject(subject, "utf8");
            message.setFrom(fromAddress);
            message.addRecipient(Message.RecipientType.TO, getToAddress(to));
            message.setContent(multipart);
        } catch (MessagingException e) {
            e.printStackTrace();
        }

        try {
            Transport transport = mailSession.getTransport("smtp");
            transport.connect(SMTP_HOST_NAME, SMTP_AUTH_USER, SMTP_AUTH_PWD);
            transport.sendMessage(message, message.getRecipients(Message.RecipientType.TO));
            transport.close();
        } catch (MessagingException e) {
            throw new EmailException("Couldn't send message to: " + to, e);
        }
    }

    private Session getMailSession() {
        Properties props = new Properties();
        props.put("mail.smtp.host", SMTP_HOST_NAME);
        props.put("mail.smtp.port", PORT);
        props.put("mail.smtp.user", SMTP_AUTH_USER);

        props.put("mail.smtp.auth", AUTH);
        props.put("mail.smtp.starttls.enable", STARTTLS);

        props.put("mail.smtp.socketFactory.port", PORT);
        props.put("mail.smtp.socketFactory.class", SOCKET_FACTORY);
        props.put("mail.smtp.socketFactory.fallback", "false");

        Session session = Session.getDefaultInstance(props, null);

        if (debug) {
            session.setDebug(true);
        }

        return session;
    }

    private InternetAddress getToAddress(String to) throws AddressException {
        return (debug)
                ? new InternetAddress("[email protected]")
                : new InternetAddress(to);
    }

    private class EmailException extends Exception {
        public EmailException(String s, Throwable throwable) {
            super(s, throwable);
        }
    }
}