try this code snippet

Enumeration e1 = request.getHeaderNames();

   while (e1.hasMoreElements())

   {

	   String header1 = (String)e1.nextElement();

       Enumeration e11 = request.getHeaders(header1);

	   while (e11.hasMoreElements())

	   {

           out.println("value of "+ header1 +" is :"+(String)e11.nextElement());
  
	   }

   }

it is used for getting all the headers with the request.