List of Most Commonly Used CGI Equivalents of Servlets

 AUTH_TYPE        request.getAuthType()CONTENT_LENGTH   request.getContentLength()CONTENT_TYPE     request.getContentType()DOCUMENT_ROOT    getServletContext().getRealPath()PATH_INFO        request.getPathInfo()PATH_TRANSLATED  request.getPathTranslated()QUERY_STRING     request.getQueryString()REMOTE_ADDR      request.getRemoteAddr()REMOTE_HOST      request.getRemoteHost()REMOTE_USER      request.getRemoteUser()REQUEST_METHOD   request.getMethod()SCRIPT_NAME      request.getServletPath()SERVER_NAME      request.getServerName()SERVER_PORT      request.getServerPort()SERVER_PROTOCOL  request.getProtocol()SERVER_SOFTWARE  getServletContext().getServerInfo()

HTTP_XXX_YYY Variables of the form HTTP_HEADER_NAME can be accessed using the request.getHeader(Header-Name)

Example:

 HTTP_REFERER    by request.getHeader("Referer")HTTP_COOKIE     by request.getHeader("Cookie")HTTP_USER_AGENT by request.getHeader("User-Agent")