Identify html form or its encoding (text or file) in servlet

Question

How do I recognize in a servlet whether the request sent using HTML form has enctype multipart/form-data or the default application/x-www-form-urlencoded?

Alternatively: is there any other way to recognize which form was used? request.getParameter("some_param") works only with default encoding.

Answer 1

I'm using Apache Commons FileUpload for multipart, but wasn't sure how to switch between handling multipart and default forms

Use Apache Commons FileUpload's own ServletFileUpload#isMultipartContent() to check it.

if (ServletFileUpload.isMultipartContent(request)) {
    // Parse with FileUpload.
}
else {
    // Use normal getParameter().
}

See also:

• Apache Commons FileUpload User's Guide

Answer 2

You can identify using Content-Type: header

if(HttpServletRequest.getContentType().contains("form-data")){
   //handle multipart data
 ....
} else if(HttpServletRequest.getContentType().contains("x-www-form-urlencoded")){
   //handle from data
 ....
}

If the web container supports Servlet 3.0, the use HttpServletRequest.getParts() API.

if(request.getParts() !=null){
  //handle multipart
} else {
  //handle form data
}