How to set content-type for the file in multipart upload when using RestTemplate (from a rest client)

Question

The file i'm trying to upload will always be a xml file. I want to set the content-type as application/xml Here is my code:

         MultiValueMap<String, Object parts = new LinkedMultiValueMap<String,
         Object(); parts.add("subject", "some info"); 
         ByteArrayResource xmlFile = new    ByteArrayResource(stringWithXMLcontent.getBytes("UTF-8")){
                 @Override
                 public String getFilename(){
                     return documentName;
                 }             
             };

     parts.add("attachment", xmlFile);

//sending the request using RestTemplate template;, the request is successfull 
String result = template.postForObject(getRestURI(), httpEntity,String.class);      
//but the content-type of file is 'application/octet-stream'

the raw request looks like this:

    Content-Type:
    multipart/form-data;boundary=gbTw7ZJbcdbHIeCRqdX81DVTFfA-oteHHEqgmlz
    User-Agent: Java/1.7.0_67 Host: some.host Connection: keep-alive
    Content-Length: 202866

    --gbTw7ZJbcdbHIeCRqdX81DVTFfA-oteHHEqgmlz Content-Disposition: form-data;    name="subject" Content-Type: text/plain;charset=ISO-8859-1
    Content-Length: 19

    some info

    --gbTw7ZJbcdbHIeCRqdX81DVTFfA-oteHHEqgmlz Content-Disposition: form-data;   name="attachment"; filename="filename.xml" Content-Type:
    application/octet-stream Content-Length: 201402

    ....xml file contents here ..

The content-type of the file is being generated as 'application/octet-stream' where as i want it to be 'application/xml' How can i set the content type for the file?

Answer 1

I figured out the solution after taking hint from this link:

Making a multipart post request with compressed jpeg byte array with spring for android

Solution is to put the ByteArrayResource in a HttpEntity with required header and add the HttpEntity to Multivaluemap (Instead of adding ByteArrayResource itself.)

Code:

Resource xmlFile = new ByteArrayResource(stringWithXMLcontent.getBytes("UTF-8")){
            @Override
            public String getFilename(){
                return documentName;
            }
        };
        HttpHeaders xmlHeaders = new HttpHeaders();
        xmlHeaders.setContentType(MediaType.APPLICATION_XML);
        HttpEntity<Resource> xmlEntity = new HttpEntity<Resource>(xmlFile, xmlHeaders);
        parts.add("attachment", xmlEntity);