Abaixo segue um exemplo de código utilizando a classe GenericServlet:
package br.aiec; import java.io.IOException; import javax.servlet.GenericServlet; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; public class GenericoDemoServlet extends GenericServlet { @Override public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException { response.getWriter().println( "Criando um Servlet a partir da classe GenericServlet"); response.getWriter().println("IP: " + request.getRemoteAddr()); response.getWriter().println("PORTA: " + request.getRemotePort()); } }