Knowledge, Technology and Information: Membuat Servlet Context dan Listener di Java Servlet

assalamualaikum kawan-kawan :)

postingan ini adalah lanjutan yang sebelumnya tentang Servlet Filter, kali ini saya akan sharing tentang program Java Servlet Context dan Listener. Langsung aja kita buat programnya

pertama kita buat index.html


    
        
        
    
    
        view servlet context

kemudian kita tambahkan script dibawah ini :

lalu kita buat ServletContextClass.java

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

/**
 *
 * @author ROOT
 */
public class ServletContextClass extends HttpServlet {

    /** 
     * Processes requests for both HTTP GET and POST 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");
        PrintWriter out = response.getWriter();
        try {
            /* TODO output your page here*/
            out.println("");
            out.println("");
            out.println("Servlet ServletContextClass");
            out.println("");
            out.println("");
            out.println("
Servlet ServletContextClass at " + request.getContextPath() + "
");
            out.println("");
            out.println("");

        } finally {
            out.close();
        }
    }

    // 
    /** 
     * Handles the HTTP GET 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);
        response.setContentType("text/html; charset=UTF-8");
        PrintWriter out = response.getWriter();

        ServletContext ctx = getServletContext();

        ctx.setAttribute("name", "Eresha Wikrama");
        out.print(ctx.getAttribute("name"));

        Enumeration temp = ctx.getAttributeNames();
        while (temp.hasMoreElements()) {
            String attrName = (String) temp.nextElement();
            out.print("Attribut " + attrName + " , nilainya = " + ctx.getAttribute(attrName));
        }

        out.print("

getServletContextName() : " + ctx.getServletContextName());

        out.print("
" + ctx.getInitParameter("bhs1"));
        Enumeration temp2 = ctx.getInitParameterNames();
        while (temp2.hasMoreElements()) {
            String paramName = (String) temp2.nextElement();
            out.print("
Attribut " + paramName + " , nilainya = " + ctx.getInitParameter(paramName));
        }

        out.print("
getServerInfo() : " + ctx.getServerInfo());
        out.print("
getRealPath() : " + ctx.getRealPath(""));
        ctx.log("Hello world");
        ctx.setAttribute("name", "Eresha Wikrama Bogor, Teknik Informatika");
        ctx.setAttribute("name", null);

        request.setAttribute("word", "never say give up in this world");
        request.setAttribute("word", "do your best and let God do the rest");
        request.setAttribute("word", null);

        HttpSession session = request.getSession();
        session.setAttribute("userSession", "EreshaWikramaSession");
        session.setAttribute("userSession", "Mari belajar JAVA");
        session.setAttribute("userSession", null);
    }

    /** 
     * Handles the HTTP POST 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";
    }// 
}

Kemudian buat sebuah 6 buah class untuk mengimplementasikan setiap interface listener
di atas. Sebenarnya buat 1 class juga bisa untuk mengimplementasikan keenam interface
tersebut. Namun ada baiknya dipisah saja per interface, supaya lebih mudah dicerna.

ServletContextListener
Tambahkan file listener baru dengan nama ServletContextListenerClass.java. Ikuti langkah
berikut ini: