Language Basics Java

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.PrintWriter;
import java.io.IOException;
import org.apache.log4j.*;
public class LoggingServlet extends HttpServlet {
    private static Logger logger = Logger.getLogger(LoggingServlet.class);
    public void doPost(HttpServletRequest req, HttpServletResponse res)
                       throws IOException, ServletException
    {
        logger.info("invoked the LoggingServlet...");
        PrintWriter writer = res.getWriter();
        writer.println("Check your web server console...");
        writer.flush();
        writer.close();
    }
}