Javamail example with attachment

Here is an example of using JavaMail to send an email with an attachment:

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

public class SendEmailWithAttachment {
    public static void main(String[] args) {
        // Set the properties for the email
        Properties props = new Properties();
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", 587);
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");

        // Create a session
        Session session = Session.getInstance(props,
                new Authenticator() {
                    protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication("[email protected]", "your-password");
                    }
                });

        // Create a message
        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress("[email protected]"));
        message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("[email protected]"));
        message.setSubject("Test email with attachment");

        // Create a body for the email
        BodyPart messageBodyPart = new MimeBodyPart();
        messageBodyPart.setText("This is a test email with an attachment.");

        // Create a multipart message
        Multipart multipart = new MimeMultipart();
        multipart.addBodyPart(messageBodyPart);

        // Add an attachment to the message
        File file = new File("path/to/attachment.txt");
        DataSource source = new FileDataSource(file);
        BodyPart attachment = new MimeBodyPart();
        attachment.setDataHandler(new DataHandler(source));
        attachment.setFileName(file.getName());
        multipart.addBodyPart(attachment);

        // Set the message body
        message.setContent(multipart);

        // Send the email
        Transport.send(message);
    }
}

This example uses the javax.mail package to send an email with an attachment. Here's a breakdown of the code:

1. We set the properties for the email, including the SMTP host, port, authentication, and startTLS enable.
2. We create a session using the Session class, passing in the properties and an authenticator that provides the username and password for the email account.
3. We create a message using the Message class, setting the from address, to address, subject, and body.
4. We create a body part for the email using the MimeBodyPart class, setting the text content.
5. We create a multipart message using the MimeMultipart class, adding the body part to it.
6. We add an attachment to the message using the MimeBodyPart class, setting the file name and data source.
7. We set the message body using the setContent method, passing in the multipart message.
8. We send the email using the Transport class.

Note that you'll need to replace the placeholders ([email protected], your-password, [email protected], and path/to/attachment.txt) with your actual email account credentials and attachment file path.