Enumeration enume = request.getHeaderNames();
String paramName = null; //パラメータ名
String paramVal = null; //値
while(enume.hasMoreElements()){
paramName = (String)enume.nextElement();
paramVal = request.getHeader(paramName);
out.println("パラメータ名:" + paranName);
out.println("値:" + paramVal);
}