谁能帮助我解决这个发送带ATTACHMENT的HTML格式MAIL的问题？？

[SophiaQ]

HI，各位高手，谁能帮我这个忙？我遇到点问题。

我想发送HTML格式的邮件，
而当邮件不带ATTACHMENT的时候，发送成功；
当带附件时，发送的却总是PLAIN TEXT的格式，WHY？
下面是我的CODE：

/*Begin*/
protected void doSendMessage(Dictionary fields)
throws IOException, MessagingException, javax.servlet.ServletException
{

String smtpServer = (String) fields.get("smtpServer");
String mailer = "Ibm Bpportal SendMail";

Properties props = System.getProperties();
props.put("mail.smtp.host", smtpServer);

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

Message msg = new MimeMessage(session);
msg.setFrom(new InternetAddress((String)fields.get("from")));

InternetAddress[] tos = InternetAddress.parse((String)fields.get("to"));
msg.setRecipients(Message.RecipientType.TO, tos);

if(fields.get("cc") != null)
{
InternetAddress[] ccs = InternetAddress.parse((String)fields.get("cc"));
msg.setRecipients(Message.RecipientType.CC,ccs);
}
msg.setSubject((String)fields.get("subject"));

msg.setSentDate(new Date());
msg.setHeader("Content-Type", "text/html; charset=gb2312");


if(null == fields.get("attachment"))
{
msg.setText((String)fields.get("body"));
msg.setContent((String)fields.get("body"),"text/html");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
msg.setDataHandler(new DataHandler(new ByteArrayDataSource((String)fields.get("body"), 'text/html")));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
}
else
{
BodyPart body = new MimeBodyPart(),
attachment = (BodyPart)fields.get("attachment");

body.setText((String)fields.get("body"));
body.setContent((String)fields.get("body"),"text/html");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
body.setDataHandler(new DataHandler(new ByteArrayDataSource((String)fields.get("body"),"text/html")));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MimeMultipart multipart = new MimeMultipart();
multipart.addBodyPart(body);
multipart.addBodyPart(attachment);
msg.setContent(multipart);
}

Transport.send(msg);

}
/*End*/