PAWW zapis do pliku,listner

AppListner.java
//-------
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package listners;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * Web application lifecycle listener.
 *
 * @author student
 */
public class AppListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        sce.getServletContext().setAttribute("atrybut 1", "wartosc 1");
        //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
   public void contextDestroyed(ServletContextEvent sce) {
        String atr1 = (String) sce.getServletContext().getAttribute("atrybut 1");
        String filename = (String) sce.getServletContext().getInitParameter("filename");

        try {
            PrintWriter writer = new PrintWriter(new File("/home/student/" + filename));
            writer.println(atr1);
            writer.close();

        } catch (FileNotFoundException ex) {
            Logger.getLogger(MyContextListener.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

//-----
servelet.java
//--
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author student
 */
public class servelet extends HttpServlet {

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet servelet</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet servelet at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
            ServletContext sce=this.getServletContext();
            out.println(sce.getAttribute("atrybut 1"));
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

//--
web.xml
//----
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <listener>
        <description>ServletContextListener</description>
        <listener-class>listners.AppListener</listener-class>
        <param-name>clientName</param-name>
        <param-value>Politechnika Białostocka</param-value>
    </listener>
    <servlet>
        <servlet-name>servelet</servlet-name>
        <servlet-class>servelet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>servelet</servlet-name>
        <url-pattern>/servelet</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

//----