attachment problems in using axis

[King Minxiao]

I wrote a webservice to send files to client with axis attachment. Here is my method doWithAttachment().
public void doWithAttachment() {
   Message repMsg =3D AxisEngine.getCurrentMessageContext().getResponseMessage();
    AttachmentPart ap =3D repMsg.createAttachmentPart();
    ap.setDataHandler(new DataHandler(new FileDataSource("C:\\temp\\output\\test.txt")));
    repMsg.addAttachmentPart(ap);
    repMsg.dispose();
}
The content of file C:\\temp\\output\\test.txt is "This is a file used to testing attachments in axis".
I received badly soap message when this method is invoked.Here is an example for my received soap message.

------=_Part_11_10258369.1134353376973
Content-Type: text/xml; charset=UTF-8
Content-Transfer-Encoding: binary

@@@lable
Content-Id: <B2D785656F586DD1E238D3CD93B71D2F>

<?xml version="1.0" encoding="UTF-8"?><soapenv:Envelope xmlns:soapenv=" http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance"><soapenv:Body/></soapenv:Envelope>
------=_Part_11_10258369.1134353376973
Content-Type: text/plain
Content-Transfer-Encoding: binary
Content-Id: <84AD45638D8A4A56555EAC788D829480>

I have to resolve to problems.
(1).Something is missed at the end of this soap message.They are attachment-content and the attachment-caption.
(2).At the lable of soap message(just @@@lable at above),I want to add something just like "Content-Length: 100",What should I do in my method?
Any suggestion is expected.

Mxking.
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