[Java] メール送信（単一メール・複数BCC宛先）

MailSender.java

import javax.mail.*;
public class MailSender {
  private final Properties props = loadProperties("/mail/MailSender.properties");
  private final Session session = createSession();

  private Properties loadProperties(String propPath) {
    try {
      Properties res = new Properties();
      res.load(MailSender.class.getResourceAsStream(propPath));
      return res;
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

  private Session createSession() {
    Session res = Session.getDefaultInstance(props);
    res.setDebug(Boolean.valueOf(props.getProperty("session.debug")));
    return res;
  }

  public void sendBcc(List<String> addresses, String subject, String body) {
    try {
      MimeMessage message = createBccMessage(addresses, subject, body);
      sendMessage(message);
    } catch (MessagingException e) {
      throw new RuntimeException(e);
    }
  }

  private MimeMessage createBccMessage(List<String> bcc, String subject,
      String body) throws MessagingException {
    MimeMessage message = createMessage(subject, body);
    Address[] bccArray = toAddressArray(bcc);
    message.setRecipients(Message.RecipientType.BCC, bccArray);
    return message;
  }

  private MimeMessage createMessage(String subject, String body)
      throws MessagingException {
    MimeMessage message = new MimeMessage(session);
    String charset = props.getProperty("message.charset");
    message.setSubject(subject, charset);
    message.setText(body, charset);
    return message;
  }

  private Address[] toAddressArray(List<String> stringList)
      throws AddressException {
    List<Address> addressList = new ArrayList<Address>();
    for (String item : stringList) {
      addressList.add(new InternetAddress(item));
    }
    return addressList.toArray(new Address[0]);
  }

  private void sendMessage(MimeMessage message)
      throws MessagingException {
    Transport transport = session.getTransport("smtp");
    String user = props.getProperty("transport.user");
    String password = props.getProperty("transport.password");
    transport.connect(user, password);
    try {
      transport.sendMessage(message, message.getAllRecipients());
    } finally {
      transport.close();
    }
  }
}

MailSender.properties

# JavaMail API
mail.smtp.host=smtp.gmail.com
mail.smtp.port=587
mail.smtp.auth=true
mail.smtp.starttls.enable=true
[email protected]

# dedicated
[email protected]
transport.password=xxxxxxxx
message.charset=ISO-2022-JP
session.debug=true