Spring MVC Framework: MultipartResolver with PUT method

Question

I'm developing a spring mvc app with framework 3.2.3.RELEASE

In my app I handle Multipart with StandardServletMultipartResolver, but with apache commons-fileupload 1.3 the things are the same.

I would like to know why the implementation of isMultipart method take in account only POST method, and not PUT method. If I want to update an entity and the related file I must do it with a POST.

Looking at org.springframework.web.multipart.support.Standard ServletMultipartResolver:

public boolean isMultipart(HttpServletRequest request) {
    // Same check as in Commons FileUpload...
    if (!"post".equals(request.getMethod().toLowerCase()) ) {
        return false;
    }
    String contentType = request.getContentType();
    return (contentType != null && contentType.toLowerCase().startsWith("multipart/"));
}

while in org.apache.commons.fileupload.servlet.ServletFileU pload I have:

public static final boolean isMultipartContent(HttpServletRequest request) {
    if (!POST_METHOD.equalsIgnoreCase(request.getMethod() )) {
        return false;
    }
    return FileUploadBase.isMultipartContent(new ServletRequestContext(request));
}

Is not a thing of vital importance, in fact just use the POST method intead of PUT works.. But I want to undertand why PUT is not taken into account!

Thank you for any reply Marco

Answer 1

RFC said

http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.6

The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server MUST NOT attempt to apply the request to some other resource.

So PUT request represent a single resource.
But multiparts means multiple resources in a single body.

http://www.w3.org/Protocols/rfc1341/7_2_Multipart.html

In the case of multiple part messages, in which one or more different sets of data are combined in a single body, a "multipart" Content-Type field must appear in the entity's header. The body must then contain one or more "body parts," each preceded by an encapsulation boundary, and the last one followed by a closing boundary.

Therefore by semantic of PUT request doesn't match with multipart data. And the POST is matched because requested URI of POST request is "handler of enclosed entities".