不难，请看javamail 发送附件的例子

Here is the code to send an attachment:
import java.util.Properties;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
public class AttachExample {
  public static void main (String args[])
      throws Exception {
    String host = args[0];
    String from = args[1];
    String to = args[2];
    String fileAttachment = args[3];
    // Get system properties
    Properties props = System.getProperties();
    // Setup mail server
    props.put("mail.smtp.host", host);
    // Get session
    Session session =
      Session.getInstance(props, null);
    // Define message
    MimeMessage message =
      new MimeMessage(session);
    message.setFrom(
      new InternetAddress(from));
    message.addRecipient(
      Message.RecipientType.TO,
      new InternetAddress(to));
    message.setSubject(
      "Hello JavaMail Attachment");
    // create the message part
    MimeBodyPart messageBodyPart =
      new MimeBodyPart();
    //fill message
    messageBodyPart.setText("Hi");
    Multipart multipart = new MimeMultipart();
    multipart.addBodyPart(messageBodyPart);
    // Part two is attachment