A simple Servlet Example

A simple java servlet which gets request from a web page as parameter, process the request, set response attributes and forwards to destination page
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/*
 * LoginServlet.java
 *
 * Created on 23 Dec 2006 Saturday, 07:39
 */

package com.myairline.servlets;

import java.io.*;
import java.net.*;
import java.sql.*;

import javax.servlet.*;
import javax.servlet.http.*;

import com.myairline.db.DatabaseConn;
import com.myairline.db.UserDB;
import com.myairline.type.User;
import com.myairline.common.MyConstants;

/**
 *
 * @author ozkansari
 * @version
 */
public class LoginServlet extends HttpServlet {

/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

    // Page will be forwarded to  :::
    String destinationPage = "";

    // Make database connection  :::
    DatabaseConn dbConn = new DatabaseConn();
    Connection connection = dbConn.getConnection();

    // get command parameter that will decide which operation is performed  :::
    String cmd = (String) request.getParameter("cmd");

    // get session variable  :::
    HttpSession sessionVar = request.getSession(true);

    // Base Path
    String contextPath = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+contextPath+"/";

    // Check command and perform the proper operation :::
    if( cmd.equals("auth_user") )
    {
        // Define Variables :::
        String userName, password;
        UserDB userCheck = new UserDB();
        User userCurrent = new User();
        int authorizationResult ;
    
        // Get form parameters :::
        userCurrent.setUsername( (String) request.getParameter("username") );
        userCurrent.setPassword( (String) request.getParameter("password") );
        authorizationResult = userCheck.doAuthentication( userCurrent );

        if( authorizationResult == MyConstants.LOGGED_IN ) {
        
            sessionVar.setAttribute("userObject",userCurrent);
        
            String rolename = userCurrent.getRolename();
        
            if( rolename.compareToIgnoreCase("customer") == 0 ){
                destinationPage = "/customer/customerHome.jsp";
            } else if( rolename.compareToIgnoreCase("agency") == 0 ){
                destinationPage = "/agency/agencyHome.jsp";
            } else if( rolename.compareToIgnoreCase("admin") == 0 ){
                destinationPage = "/admin/adminHome.jsp";
            }
        
        }
        else {
            // Set Attribute and destination Page :::
            Integer reason = new Integer( authorizationResult );
            request.setAttribute( "login", reason );
            destinationPage = "/home.jsp";
        }
   
    }

    // Clean your garbage :::
    dbConn.closeConnection();

    // Go to destination page :::
    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(destinationPage);
    dispatcher.forward(request, response);

}

// <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
     */
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
     */
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
    processRequest(request, response);
}

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