Berbagi Ilmu Berbagi Rejeki

WHAT'S NEW?

Assalamu'alaikum ..
Mari kita lanjutkan ngulik java, sebelumnya di part 1 kita sudah membahas tentang servlet filternya bisa dilihat di Servlet Filter Login.
postingan kali ini saya akan mengangkat tema ServletContext dan ContextListener ..

ServletContext adalah suatu interface yang digunakan untuk berkomunikasi dengan servlet container. Dalam sebuah aplikasi web hanya terdapat satu ServletContext saja, dan seluruh komponen aplikasi web dapat saling menggunakannya.

Sedangkan ContextListener berfungsi seperti listener di java yaitu mendeteksi suatu event dan memberikan respons terhadap event tersebut. Di dalam servlet, jika kita mendeklarasikan sebuah listener pada objek tertentu, maka servlet-container akan menghasilkan event yang sesuai pada saat terjadi perubahan dalam objek tersebut.

Sekarang langsung saja buat sebuah project java web baru dengan nama MyServletListener menggunakan IDE kalian (saya menggunakan netbeans 8.0), lalu tambahkan code berikut di file index.jsp atau index.html pada tag body :

 view servlet context

Lalu buatlah sebuah servlet baru dengan nama ServletContextClass, jangan lupa untuk menceklis "Add Information to Deployment descriptor (web.xml)" kemudian rubah file ServletContextClass.java menjadi seperti code dibawah ini :

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 fitri
 */
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");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("");
            out.println("");
            out.println("");
            out.println("Servlet ServletContextClass");            
            out.println("");
            out.println("");
            out.println("
Servlet ServletContextClass at " + request.getContextPath() + "
");
            out.println("");
            out.println("");
        }
    }

    // 
    /**
     * 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
     */
    
    /**
     * 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
     */
    

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException{
        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("
Atribut " + attrName + " , nilainya = " + ctx.getAttribute(attrName));
        }
        
        out.print ("

getServletContextName() : " + ctx.getServletContextName());
        
        out.print("
" + ctx.getInitParameter("bhs1"));
        Enumeration temp2 = ctx.getInitParameterNames();
        while (temp.hasMoreElements()) {
           String paramName = (String) temp2.nextElement();
           out.print("
Atribut " + paramName + " , nilainya = " + ctx.getAttribute(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);
        }
    
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws  ServletException, IOException{
            processRequest(request, response);
            }
    
    @Override
    public String getServletInfo(){
        return "Short Description";
    }
 }

Setelah selesai, kita akan lanjutkan membuat ContextListener dengan nama ServletContextListenerClass.
add new di dalam package sebelumnya, pilih Web Application Listener. beri nama ServletContextListenerClass, jangan dulu klik Finish! pada kolom interface to implement, centang context listener. Lalu klik finish dan ubah code yang ada menjadi seperti dibawah ini :

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/*
 * 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.
 */

/**
 * Web application lifecycle listener.
 *
 * @author fitri
 */



public class ServletContextListenerClass implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        ServletContext ctx = sce.getServletContext();
        if (ctx != null){
            ctx.log("Context : " + ctx.getServletContextName() + " sudah diinisialisasi");
            
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        ServletContext ctx = sce.getServletContext();
        if (ctx != null){
            ctx.log("Context : " + ctx.getServletContextName() + " sudah dihancurkan");
            
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

Ketika proses inisialisasi dari aplikasi kita telah dimulai, maka fungsi contextInitialized akan dijalankan. Sedangkan ketika servlet-context akan dishutdown maka fungsi contextDestroyed akan dijalankan. Selanjutnya kita buat file seperti ServletContextClass beri nama ServletContextAttributeListenerClass dan pada kolom Interfaces to Implement centang Context Attribute Listener lalu Finish. ubah code file tersebut seperti di bawah ini :

import javax.servlet.ServletContext;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;

/*
 * 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.
 */

/**
 * Web application lifecycle listener.
 *
 * @author fitri
 */


public class ServletContextAttributeListenerClass implements ServletContextAttributeListener {

    @Override
    public void attributeAdded(ServletContextAttributeEvent event) {
        ServletContext ctx = event.getServletContext();
        if (ctx != null)
        {
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "attribute " + event.getName() + " dengan nilai : " + event.getValue() + " Sudah ditambahkan"
            );
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void attributeRemoved(ServletContextAttributeEvent event) {
        ServletContext ctx = event.getServletContext();
        if (ctx != null)
        {
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "attribute " + event.getName() + " dengan nilai : " + event.getValue() + " Sudah dihapus"
            );
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void attributeReplaced(ServletContextAttributeEvent event) {
        ServletContext ctx = event.getServletContext();
        if (ctx != null)
        {
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "attribute " + event.getName() + " dengan nilai : " + event.getValue() + " Sudah diubah"
            );
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

Ketika ada suatu attribute baru yang ditambahkan ke dalam servlet-context maka fungsi attributeAdded akan dijalankan, ketika suatu attribute dihapus maka fungsi attributeRemoved dijalankan, dan ketika suatu attribute diubah nilainya maka fungsi attributeReplaced dijalankan.

Selanjutnya buat file ServerListener dengan nama ServletRequestListenerClass, pada kolom
Interfaces to Implement pilih Request Listener:
kemudian ubah kode seperti dibawah ini :

import javax.servlet.ServletContext;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;

/*
 * 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.
 */

/**
 * Web application lifecycle listener.
 *
 * @author fitri
 */
public class ServletRequestListenerClass implements ServletRequestListener {

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        ServletContext ctx = sre.getServletContext();
        if(ctx != null)
        {
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "request " + sre.getServletRequest() + " sudah  dihancurkan");
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        ServletContext ctx = sre.getServletContext();
        if(ctx != null)
        {
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "request " + sre.getServletRequest() + " sudah  diinisialisasi");
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

Selanjutnya buat file ServerListener dengan nama HttpSessionListenerClass, pada kolom Interfaces to Implement pilih HTTP Session Listener:

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

/*
 * 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.
 */

/**
 * Web application lifecycle listener.
 *
 * @author fitri
 */
public class HttpSessionListenerClass implements HttpSessionListener {

    @Override
    public void sessionCreated(HttpSessionEvent se) {
        ServletContext ctx = se.getSession().getServletContext();
        if(ctx != null){
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "session " + se.getSession().getId() + " sudah dibuat"
            );
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        ServletContext ctx = se.getSession().getServletContext();
        if(ctx != null){
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "session " + se.getSession().getId() + " sudah dihancurkan"
            );
        }
//        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

Selanjutnya buat file ServerListener dengan nama HttpSessionAttributeListenerClass, pada kolom Interfaces to Implement pilih HTTP Session Attribute Listener
kemudian ubah code seperti dibawah :

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

/*
 * 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.
 */

/**
 * Web application lifecycle listener.
 *
 * @author fitri
 */
public class HttpSessionAttributeListenerClass implements HttpSessionAttributeListener {

    @Override
    public void attributeAdded(HttpSessionBindingEvent event) {
        ServletContext ctx = event.getSession().getServletContext();
        if (ctx != null){
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "session attribute " + event.getName() + " dengan nilai : "
                    + event.getValue() + " sudah ditambahakan"
            );
        }
//        /throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent event) {
        ServletContext ctx = event.getSession().getServletContext();
        if (ctx != null){
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "session attribute " + event.getName() + " dengan nilai : "
                    + event.getValue() + " sudah dihapus"
            );
        }
//        /throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent event) {
        ServletContext ctx = event.getSession().getServletContext();
        if (ctx != null){
            ctx.log("Context " + ctx.getServletContextName() + ", "
                    + "session attribute " + event.getName() + " dengan nilai : "
                    + event.getValue() + " sudah diubah"
            );
        }
//        /throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

Sekarang daftarkan class ServletContextClass sebagai sebuah servlet dan keenam class di atas sebagai sebuah listener. Konfigurasinya kita lakukan di file web.xml, seperti ini:


    
        bhs1
        Java
    
    
        bhs2
        C++
    
    
        bhs3
        C
    
    
        bhs4
        VB.Net
    
    
        bhs5
        JSP
    
    
        ServletContextListener
        ServletContextListenerClass
    
    
        ServletContextAttributeListener
        ServletContextAttributeListenerClass
    
    
        RequestListener
        ServletRequestListenerClass
    
    
        HttpSessionListener
        HttpSessionListenerClass
    
    
        RequestAttributeListener
        HttpSessionAttributeListener
    
    
        RequestAttributeListener
        ServletRequestAttributeListener
    
    
        ServletContext
        ServletContext
    
    
        ServletContextClass
        ServletContextClass
    
    
        ServletContext
        /ServletContext
    
    
        ServletContextClass
        /ServletContextClass
    
    
        
            30

Dalam prakteknya, listener ServletContextListener sering digunakan untuk melakukan proses connect dan disconnect dari database server. Sedangkan listener HttpSessionListener sering digunakan untuk mencatat ativitas user di database. Misalnya kapan user login dan kapan user logout dari aplikasi kita.

Selamat bereksplorasi .. Terima kasih.

Wassalamualaikum wr. wb

Coming soon : Membuat Servlet Filter dan Servlet Listener Part 3

Assalamu'alaikum ...

Hallo, lama tak berjumpa. postingan kali ini saya masih akan mengulas yang berhubungan dengan servlet.

oke, langsung aja kita akan membuat :
1. Servlet Filter Login
buat project baru di netbean kamu dengan memlih web application, beri nama nama filterlogin. setelah buat project baru, buka file index.html lalu masukkan kode berikut :

    
<!DOCTYPE html>
<html>
    <head>
        <title></title>
        <meta charset="UTF-8"> 
        <meta name="viewport" content="width=device-width, initial-scale=1.0"> 
    </head>
    <body>
         <form action="LoginServlet" method="post"> 
             Username: <input type="text" name="user"> 
             <br> 
             Password: <input type="password" name="pwd">
             <br>
             <input type="submit" value="Login"> 
         </form> 
    </body>
</html>

kemudian buat file servlet baru dengan nama LoginServlet.java

 
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher; 
import javax.servlet.ServletException;
import javax.servlet.http.Cookie; 
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; 

/**
 *
 * @author fitri
 */
public class LoginServlet extends HttpServlet {
     private static final long serialVersionUID = 1L;
     private final String userID = "admin";
     private final String password = "123"; 

    /**
     * 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");
        PrintWriter out = response.getWriter();
        try {
            /* TODO output your page here. You may use following sample code. */
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet LoginServlet</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet LoginServlet at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        } finally {            
            out.close();
        }
    }

    // <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);
        String user = request.getParameter("user");
        String pwd = request.getParameter("pwd");
        
        if (userID.equals(user) && password.equals(pwd)) { 
        HttpSession session = request.getSession();
        session.setAttribute("user", "Pankaj");
        //setting session to expiry in 30 mins 88 
        session.setMaxInactiveInterval(30 * 60);
        Cookie userName = new Cookie("user", user); 
        userName.setMaxAge(30 * 60);
        response.addCookie(userName);
        response.sendRedirect("LoginSuccess.jsp");
        } else {
            RequestDispatcher rd = getServletContext().getRequestDispatcher("/index.html");
            PrintWriter out = response.getWriter();
            out.println("<font color=red>Either user name or password is wrong.</font>"); 
            rd.include(request, response);
        } 
    }

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

setelah membuat servlet untuk login, kita akan membuat servlet untuk logout dengan nama file LogoutServlet.java. berikut kodenya :

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

/**
 *
 * @author fitri
 */
public class LogoutServlet 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");
        PrintWriter out = response.getWriter();
        try {
            /* TODO output your page here. You may use following sample code. */
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet LogoutServlet</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet LogoutServlet at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        } finally {            
            out.close();
        }
    }

    // <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);
         Cookie[] cookies = request.getCookies();
         if (cookies != null) {
             for (Cookie cookie : cookies) {
                 if (cookie.getName().equals("JSESSIONID")) {
                     System.out.println("JSESSIONID=" + cookie.getValue());
                     break;
                 }
             }
         }
         //invalidate the session if exists 
         HttpSession session = request.getSession(false);
         System.out.println("User=" + session.getAttribute("user"));
         if (session != null) { 
             session.invalidate();
         } 
         response.sendRedirect("index.html"); 
    }

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

lanjutkan dengan buat file RequestLoggingFilter.java

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Enumeration;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;

/**
 *
 * @author fitri
 */

public class RequestLoggingFilter implements Filter {

    private static final boolean debug = true;

    // The filter configuration object we are associated with. If
    // this value is null, this filter instance is not currently
    // configured.
    private FilterConfig filterConfig = null;
    //private ServletContext context;

    public RequestLoggingFilter() {
    }

    private void doBeforeProcessing(ServletRequest request, ServletResponse response)
    throws IOException, ServletException {
        if (debug) {
            log("RequestLoggingFilter:DoBeforeProcessing");
        }

        HttpServletRequest req = (HttpServletRequest) request;
        Enumeration params = req.getParameterNames();
        while (params.hasMoreElements()) {
        String name = params.nextElement();
        String value = request.getParameter(name);
        log(req.getRemoteAddr() + "::Request Params::{" + name + "=" + value + "}");

    }

    Cookie[] cookies = req.getCookies();
    if (cookies != null) {
        for (Cookie cookie : cookies) {
            log(req.getRemoteAddr() + "::Cookie::{" + cookie.getName() + "," + cookie.getValue() + "}");
        }
    }
    
    }

    private void doAfterProcessing(ServletRequest request, ServletResponse response)
    throws IOException, ServletException {
        if (debug) {
            log("RequestLoggingFilter:DoAfterProcessing");
        }
    }

    /**
    *
    * @param request The servlet request we are processing
    * @param response The servlet response we are creating
    * @param chain The filter chain we are processing
    *
    * @exception IOException if an input/output error occurs
    
    * @exception ServletException if a servlet error occurs
    */
    public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain) throws IOException, ServletException {

        if (debug) {
            log("RequestLoggingFilter:doFilter()");
        }

        doBeforeProcessing(request, response);

        Throwable problem = null;
        try {
            chain.doFilter(request, response);
        } catch (Throwable t) {
        // If an exception is thrown somewhere down the filter chain,
        // we still want to execute our after processing, and then
        // rethrow the problem after that.
            problem = t;
            t.printStackTrace();
        }

        doAfterProcessing(request, response);

        // If there was a problem, we want to rethrow it if it is
        // a known type, otherwise log it.
        if (problem != null) {
            if (problem instanceof ServletException) {
                throw (ServletException) problem;
            }
            if (problem instanceof IOException) {
                throw (IOException) problem;
            }
            sendProcessingError(problem, response);
        }
    }

    /**
    * Return the filter configuration object for this filter.
    */
    public FilterConfig getFilterConfig() {
        return (this.filterConfig);
    }

    /**
    * Set the filter configuration object for this filter.
    *
    * @param filterConfig The filter configuration object
    */
    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }

    /**
    * Destroy method for this filter
    */
    public void destroy() {
    }

    /**
    * Init method for this filter
    */

    public void init(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
        if (filterConfig != null) {
            if (debug) {
                log("RequestLoggingFilter:Initializing filter");
            }
        }
    }

    /**
    * Return a String representation of this object.
    */
    @Override
    public String toString() {
        if (filterConfig == null) {
            return ("RequestLoggingFilter()");
        }
        StringBuffer sb = new StringBuffer("RequestLoggingFilter(");
        sb.append(filterConfig);
        sb.append(")");
        return (sb.toString());
    }

    private void sendProcessingError(Throwable t, ServletResponse response) {
        String stackTrace = getStackTrace(t);

        if (stackTrace != null && !stackTrace.equals("")) {
            try {
                response.setContentType("text/html");
                PrintStream ps = new PrintStream(response.getOutputStream());
                PrintWriter pw = new PrintWriter(ps);
                pw.print("\n\nError\n\n\n");

                // PENDING! Localize this for next official release
                pw.print("The resource did not process correctly
\n\n");
                pw.print(stackTrace);
                pw.print("\n"); //NOI18N
                pw.close();
                ps.close();
                response.getOutputStream().close();
            } catch (Exception ex) {
            }
        } else {
            try {
                PrintStream ps = new PrintStream(response.getOutputStream());
                t.printStackTrace(ps);
                ps.close();
                response.getOutputStream().close();
            } catch (Exception ex) {
            }
        }
    }

    public static String getStackTrace(Throwable t) {
        String stackTrace = null;
            try {
                StringWriter sw = new StringWriter();
                PrintWriter pw = new PrintWriter(sw);
                t.printStackTrace(pw);
                pw.close();
                sw.close();
                stackTrace = sw.getBuffer().toString();

            } catch (Exception ex) {
            }
    return stackTrace;
    }

    public void log(String msg) {
        filterConfig.getServletContext().log(msg);
    }

}

selanjutnya buat file servlet AuthenticationFilter.java

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig; 
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 *
 * @author fitri
 */
public class AuthenticationFilter extends HttpServlet {

    private static final boolean debug = true; 
    
    // The filter configuration object we are associated with.  If 
    // this value is null, this filter instance is not currently 
    // configured. 
    private FilterConfig filterConfig = null; 

    public AuthenticationFilter() {
    } 
    
    private void doBeforeProcessing(ServletRequest request, ServletResponse response)
        throws IOException, ServletException { 
        if (debug) { 
           log("AuthenticationFilter:DoBeforeProcessing"); 
        }
        
    }
    
    private void doAfterProcessing(ServletRequest request, ServletResponse response) 
        throws IOException, ServletException { 
        if (debug) { 
            log("AuthenticationFilter:DoAfterProcessing"); 
         }
        
       
    } 
    
    /**
     * 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
     */
     public void doFilter(ServletRequest request, ServletResponse response, 
         FilterChain chain)
         throws IOException, ServletException { 
         
         if (debug) { 
            log("AuthenticationFilter:doFilter()");
         } 

        doBeforeProcessing(request, response);
        
        Throwable problem = null; 
        try {  
            HttpServletRequest req = (HttpServletRequest) request;
            HttpServletResponse res = (HttpServletResponse) response;
            
            String uri = req.getRequestURI();
            log("Requested Resource::" + uri);
            
            HttpSession session = req.getSession(false); 
                if (session == null && !(uri.endsWith("html") || uri.endsWith("LoginServlet"))) {
                    log("Unauthorized access request");
               
            res.sendRedirect("index.html");
                }else{ 
            // pass the request along the filter chain
                 chain.doFilter(request, response); 
                } 
       } catch (Throwable t) { 
        // If an exception is thrown somewhere down the filter chain, 
        // we still want to execute our after processing, and then 
        // rethrow the problem after that. 
            problem = t;
            t.printStackTrace(); 
        } 

        doAfterProcessing(request, response); 

        // If there was a problem, we want to rethrow it if it is 
        // a known type, otherwise log it. 
        if (problem != null) { 
            if (problem instanceof ServletException) {
            throw (ServletException) problem;
            } 
            if (problem instanceof IOException) { 
                throw (IOException) problem; 
            } 
            sendProcessingError(problem, response); 
         } 
        } 
 /** 
 * Return the filter configuration object for this filter. 
 */ 
     public FilterConfig getFilterConfig() { 
         return (this.filterConfig); 
        } 
        /** 
        * Set the filter configuration object for this filter. 
        * 
        * @param filterConfig The filter configuration object 
        */ 

        public void setFilterConfig(FilterConfig filterConfig) { 
        this.filterConfig = filterConfig; 
        } 
        /** 
        * Destroy method for this filter 
        */ 

         public void destroy() { 
        } 
        /** 
        * Init method for this filter
        */ 
        public void init(FilterConfig filterConfig) { 
        this.filterConfig = filterConfig;
        if (filterConfig != null) {
                if (debug) { 
                        log("AuthenticationFilter:Initializing filter");
                }
        } 
        } 
        /** 
        * Return a String representation of this object. 
        */ 

        @Override
        public String toString() { 
            if (filterConfig == null) { 
                return ("AuthenticationFilter()"); 
            }
            StringBuffer sb = new StringBuffer("AuthenticationFilter("); 
            sb.append(filterConfig); 
            sb.append(")"); 
            return (sb.toString());
        } 

        private void sendProcessingError(Throwable t, ServletResponse response) {
            String stackTrace = getStackTrace(t); 
            if (stackTrace != null && !stackTrace.equals("")) { 
                try {
                    response.setContentType("text/html"); 
                    PrintStream ps = new PrintStream(response.getOutputStream());
                    PrintWriter pw = new PrintWriter(ps);
                    pw.print("\n\nError\n\n\n"); 
                    //NOI18N 

                    // PENDING! Localize this for next official release 
                    pw.print("The resource did not process correctly
\n\n"); 
                    pw.print(stackTrace); 
                    pw.print("\n"); 
                    //NOI18N 
                    pw.close();
                    ps.close(); 
                    response.getOutputStream().close();
                } catch (Exception ex) { 
        } 
        } else { 
             try { 
                PrintStream ps = new PrintStream(response.getOutputStream()); 
                t.printStackTrace(ps); 
                ps.close(); 
                response.getOutputStream().close();
                } catch (Exception ex) {
                } 
            }
        } 

        public static String getStackTrace(Throwable t) {
            String stackTrace = null;
            try { 
                StringWriter sw = new StringWriter(); 
                PrintWriter pw = new PrintWriter(sw);
                t.printStackTrace(pw);
                pw.close(); 
                sw.close(); 
                stackTrace = sw.getBuffer().toString();
            } catch (Exception ex) {
         }
         return stackTrace;
         } 

        public void log(String msg) { 
            filterConfig.getServletContext().log(msg); 
        }

}

semua kode sudah selesai, langkah terakhir ubah di file web.xml menjadi seperti di bawah ini



    
RequestLoggingFilter
RequestLoggingFilter


AuthenticationFilter
AuthenticationFilter


RequestLoggingFilter
/*
REQUEST


AuthenticationFilter
/*


LoginServlet
LoginServlet


LogoutServlet
LogoutServlet


LoginServlet
/LoginServlet


LogoutServlet
/LogoutServlet



30

Setelah selesai semua, jalankan aplikasi Anda. Selamat Bereksplorasi :) tunggu di part 2 ya .. Wassalamualaikum wr. wb

Assalamualaikum Wr. Wb

Sehubungan dengan adanya tugas UTS di kampus STMIK Eresha Wikrama saya akan berbagi sedikit untuk pembuatannya.
Disini kita akan membuat form inputan data menggunakan

java servlet sederhana, sebelum kita menginput data kita diharuskan untuk login, perlu digaris bawahi bahwa semua data inputan tidak disimpan kedalam database, melainkan disimpan didalam hashtable.

Sebelum kita membuat aplikasi sederhana ini, perangkat yang harus disiapkan yaitu :
1. NetBeans sebagai editor (yang saya gunakan adalah NetBeans IDE 8.0)
2. JDK 1.8 (menyesuaikan)
3. Glashfish server (bisa juga menggunakan TomCat)

Oke, kita mulai membuat aplikasi ini :

alur aplikasi yang akan kita buat seperti ini :

Pertama kita buat New Project >> Pilih Categories (Java Web) > Projects (Web Application) >> Next >> Beri Nama Project sesuai keinginan, lalu Next >> Next >> Next >> Finish

Form Login

Klik kanan pada Source Packages >> New >> Servlet..

Beri nama form dengan nama "Login" lalu Next dan beri cheklist pada "Add information to deployment descriptor (web.xml)"

tampilan yang akan kita buat untuk form login seperti dibawah ini

setelah form login servlet tadi terbuat, masukkan code dibawah ini

kita menambahkan "import javax.servlet.http.HttpSession" untuk mendukung session yang akan digunakan untuk menyimpan user name, password dan message. selebihnya java library diatas adalah default saat pertama kali dibuat form login,

VALID_NAME = digunakan untuk user name saat login
PASSWORD = digunakan untuk password saat login
FULL_NAME = digunakan untuk display nama lengkap user yang login

tambahkan kode dibawah ini untuk membuat judul form dan mendeklarasikan variable untuk digunakan saat login.

disini ada pengecekan, apabila belum login, maka aplikasi akan memunculkan form login. apabila sudah mengklik button login maka sistem akan mengecek apakah user name yang diinput sama dengan valid_name yang sudah dideklarasi sebelumnya yaitu "fitri" dan password sama dengan "f1tr1". ada 3 validasi, yaitu apakah user name yang salah, password yang salah atau keduanya.

contoh validasi jika password yang diinput salah :

Lanjutkan code sebelumnya

jika user name dan password sama maka akan masuk ke form

2. Form Input Data Mahasiswa

Buat form servlet baru seperti membuat login dengan nama InputDataMahasiswa namun tidak menceklis bagian "Add information to deployment descriptor (web.xml)"
Form yang akan kita buat seperti dibawah ini :

kita akan mulai membuat kode untuk form input mahasiswa seperti tampilan di atas, java library yang kita tambahkan hanya HttpSession untuk menyimpan message validasi yang akan dilempar ke form login

Pada form ini kita akan menerapkan Hashtable untuk menyimpan semua data yang diinput, sebelum data disimpan kedalam Hashtable, kita menggunakan class dataL untuk menampung variable data dan dimasukkan kedalam LIST[].
saat form dibuka, akan dilakukan pengecekan apakah sudah melakukan login atau belum dengan mengecek session login, jika session login kosong maka session message akan terisi dengan pesan "Anda belum login" dan tampilan form akan kembali ke form login.
contoh validasi belum login
kode dibawah ini untuk mendesain form input seperti tampilan awal dalam bentuk html

kode ini untuk membuat header table yang akan menampilkan data inputan

kode button simpan.

data yang sudah diisi dimasukkan kedalam LIST[] dataL
jika dalam mode edit, maka variable update akan terisi dengan id atau key hashtable. Jika dalam mode simpan, maka variable update akan kosong dan key yang akan diinput adalah nomor sebelumnya yang tersimpan di dalam variable jumlahData + 1.
data yang di put kedalam Hashtable adalah isi dari LIST[] dataL

sebelum menyimpan data, dilakukan validasi apakah data yang diinput ada yang kosong. jika ada maka akan muncul validasi "Lengkapi data"
kode edit data
kode hapus data
kode logout
saat logout, session login akan dihapus dan session message akan diisi dengan "Anda sudah keluar" dan akan menuju form login kembali
tampilkan data di table