Server Variables

Server Variables
Printing all the server variables in a servlet.

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Server Variables

How to display a range of CGI-style environmental variables in a servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

public class ServerVars extends HttpServlet
{

public void doGet(HttpServletRequest request,HttpServletResponse response)
   throws ServletException, IOException
   {

/* Add all environmental variables to a hash class */
      Hashtable envvars = new Hashtable();

addIfNotNull(envvars,"AUTH_TYPE",request.getAuthType());
      addIfNotNull(envvars,"CONTENT_LENGTH",String.valueOf(request.getContentLength()));
      addIfNotNull(envvars,"CONTENT_TYPE", request.getContentType());
      addIfNotNull(envvars,"DOCUMENT_ROOT",getServletContext().getRealPath("/"));
      addIfNotNull(envvars,"HTTP_ACCEPT",request.getHeader("Accept"));
      addIfNotNull(envvars,"HTTP_REFERER",request.getHeader("Referer"));
      addIfNotNull(envvars,"HTTP_ACCEPT_LANGUAGE",request.getHeader("Accept-Language"));
      addIfNotNull(envvars,"HTTP_ACCEPT_ENCODING",request.getHeader("Accept-Encoding"));
      addIfNotNull(envvars,"HTTP_CONNECTION",request.getHeader("Connection"));
      addIfNotNull(envvars,"HTTP_HOST",request.getHeader("Host"));
      addIfNotNull(envvars,"HTTP_USER_AGENT",request.getHeader("User-Agent"));
      addIfNotNull(envvars,"PATH_INFO", request.getPathInfo());
      addIfNotNull(envvars,"PATH_TRANSLATED", request.getPathTranslated());
      addIfNotNull(envvars,"QUERY_STRING", request.getQueryString());
      addIfNotNull(envvars,"REMOTE_ADDR", request.getRemoteAddr());
      addIfNotNull(envvars,"REMOTE_HOST", request.getRemoteHost());
      addIfNotNull(envvars,"REMOTE_USER", request.getRemoteUser());
      addIfNotNull(envvars,"REQUEST_METHOD", request.getMethod());
      addIfNotNull(envvars,"REQUEST_URI",request.getRequestURI());
      addIfNotNull(envvars,"SCRIPT_NAME", request.getServletPath());
      addIfNotNull(envvars,"SERVER_NAME", request.getServerName());
      addIfNotNull(envvars,"SERVER_PORT",String.valueOf(request.getServerPort()));
      addIfNotNull(envvars,"SERVER_PROTOCOL", request.getProtocol());
      addIfNotNull(envvars,"SERVER_SOFTWARE",getServletContext().getServerInfo());

/* Output */
      response.setContentType("text/html");
      PrintWriter out = response.getWriter();

out.println("<html><body>\n");
      out.println("<table border=1>\n");

// Go through all vars and print 
      Enumeration allvars = envvars.keys();
      while (allvars.hasMoreElements())
      {
         Object keyname = allvars.nextElement();

out.println("<tr>\n");
         out.println("<td>" + keyname +"</td>\n");

if (envvars.get(keyname) != null)
         {
            Object varvalue = envvars.get(keyname);
            out.println("<td>" + varvalue +"</td>\n");
         } else{
            out.println("<td>&nbsp;</td>\n");
         }
         out.println("</tr>\n");

}
      out.println("</table>");
      out.println("</body></html>");

}

/* null checker */
   private void addIfNotNull(Hashtable htable, String keyname,Object valuetoadd)
   {
      if (valuetoadd != null)
      {
         htable.put(keyname,valuetoadd);
      } else{
         htable.put(keyname,"&nbsp;");
      }

}

/** Handle GET & POST */

public void doPost(HttpServletRequest request,HttpServletResponse response)
   throws ServletException, IOException
   {
   doGet(request, response);
   }
}