how generate DataHandler instead of byte[] for SWA attachment?

[ext2]

Hi:
        I am try to write a client to invoke any existing SWA webservice;
But the generated JAX-WS interface always using byte[] instead of
DataHandler for the attachment?
        how could  I configure cxf to using DataHandler instead of byte[]?

        Thanks any suggestion;

Following is  a simplified wsdl to illustrate the problem;
<types>
<xs:element name="sayHi" type="tns:sayHi"/>
<xs:element name="sayHiResponse" type="tns:sayHiResponse"/>
<xs:element name="attachment1" type="xs:base64Binary"/>
<xs:element name="attachment2" type="xs:base64Binary"/>
<types>

  <wsdl:message name="sayHi">
    <wsdl:part element="tns:sayHi" name="parameters"/>
    <wsdl:part element="tns:attachment1" name="attachment1"/>
    <wsdl:part element="tns:attachment2" name="attachment2"/>
  </wsdl:message>

      <wsdl:input name="sayHi">
        <mime:multipartRelated>
          <mime:part>
            <soap:body parts="parameters" use="literal"/>
          </mime:part>
          <mime:part>
            <mime:content part="attachment1"
type="application/octet-stream"/>
          </mime:part>
          <mime:part>
            <mime:content part="attachment2"
type="application/octet-stream"/>
          </mime:part>
        </mime:multipartRelated>
      </wsdl:input>