package mxtj45;////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// declare imports////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// J2SE 1.3.1 importsimport java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;// J2EE 1.3.1 importsimport javax.servlet.*;import javax.servlet.http.*;// mxtj45. importsimport java.awt.*;import com.mapinfo.mapj.*;import com.mapinfo.mapxtreme.client.*;import com.mapinfo.util.*;import com.mapinfo.xmlprot.mxtj.*;////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// top-level public class/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////** * simple servlet that performs zoom / pan operations on an MDF file defined * map, such that all map images are stored on the webserver as GIF files in a * publicly accessible context directory, and client state is maintained in * a servlet session with session ID values being conveyed via URL rewriting. * * @author John Dove, MapInfo Technical Support Department, 2002 */public class NaviServlet extends HttpServlet{  //////////////////////////////////////////////////////////////////////////////  //////////////////////////////////////////////////////////////////////////////  // fields  //////////////////////////////////////////////////////////////////////////////  //////////////////////////////////////////////////////////////////////////////  //----------------------------------------------------------------------------  // static fields loaded as servlet initialization parameters  //----------------------------------------------------------------------------  /**   * absolute path of MDF file to load into all MapJ object.   */  // REQUIRED IN WEB.XML  static private String m_mdfFileToLoad;  /**   * url of the MapXtremeJava 4.5 servlet that is used for remote rendering.   */  // REQUIRED IN WEB.XML  static private String m_urlOfMapXtremeServlet;  /**   * directory to create GIF files in on webserver machine.  These GIF images   * will be referred to by URL links within the HTML documents returned to   * clients.   */  // REQUIRED IN WEB.XML  static private String m_imageDirectory;  /**   * flag that indicates if all the servlet initialization parameters were   * loaded upon servlet startup.   */  static boolean m_allInitParamsLoaded;  //----------------------------------------------------------------------------  // names of HTTP parameters that can be sent by client  //----------------------------------------------------------------------------  /**   * identifier for the http param that denotes the "type" of request sent by   * a client.   */  static private String m_param_requestType = "action";  /**   * holds X-axis value of mouse click made by client on the map.   */  static private String m_param_screenClickX = "map.x";  /**   * holds Y-axis value of mouse click made by client on the map.   */  static private String m_param_screenClickY = "map.y";  /**   * http param value that denotes zoom-in operation.   */  static private String m_requestZoomIn = "zin";  /**   * http param value that denotes zoom-out operation.   */  static private String m_requestZoomOut = "zout";  /**   * http param value that denotes pan operation.   */  static private String m_requestPan = "pan";  //----------------------------------------------------------------------------  // static fields with names for session stored objects  //----------------------------------------------------------------------------  /**   * name assigned to MapJ object when stored to session.   */  static private String m_sessionNameForMapJ = "mapj";  /**   * will be accessed via a synchronized code block to provide unique   * incrementing long values on a per client-request basis   */  static private long sequenceNumber;  // defaults to zero  //////////////////////////////////////////////////////////////////////////////  //////////////////////////////////////////////////////////////////////////////  // methods  //////////////////////////////////////////////////////////////////////////////  //////////////////////////////////////////////////////////////////////////////  public void init() throws ServletException  {    System.out.println("NAVI SERVLET INITIALIZING...");    // assume that all initialization parameters will NOT be loaded    NaviServlet.m_allInitParamsLoaded = false;    //--------------------------------------------------------------------------    // read the following initialization parameters, which should all be defined    // in the deployment descriptor (web.xml) file of the web application that    // this servlet is a part of.    //    // 1. mdfFileToLoad    // 2. urlOfMapXtremeServlet    //    // if any of these parameters are NOT obtained, we will throw an exception.    //--------------------------------------------------------------------------    m_mdfFileToLoad = this.getInitParameter("mdfFileToLoad");    m_urlOfMapXtremeServlet = this.getInitParameter("urlOfMapXtremeServlet");    m_imageDirectory = this.getInitParameter("imageDirectory");    System.out.println("");    System.out.println("SERVLET INIT PARAMETERS:");    System.out.println("  mdfFileToLoad = ["+m_mdfFileToLoad+"]");    System.out.println("  urlOfMapXtremeServlet = ["+m_urlOfMapXtremeServlet+"]");    System.out.println("  imageDirectory = ["+m_imageDirectory+"]");    System.out.println("");    if (m_mdfFileToLoad == null)    {      throw new ServletException("init param [mdfFileToLoad] was null.");    }    else if (m_urlOfMapXtremeServlet == null)    {      throw new ServletException("init param [urlOfMapXtremeServlet] was null.");    }    else if (m_imageDirectory == null)    {      throw new ServletException("init param [imageDirectory] was null.");    }    // if we made it here, it means all the needed init params were obtained    NaviServlet.m_allInitParamsLoaded = true;  }  /**   * handles HTTP GET requests.  This method will execute in a separate thread   * within the servlet container's JVM.   *   * @param req an HttpServletRequest object that contains the request the   *        client has made of the servlet   * @param resp an HttpServletResponse object that contains the response the   *        servlet sends to the client   * @throw java.io.IOException if an input or output error is detected when   *        the servlet handles the GET request   * @throw ServletException if the request for the GET could not be handled   *   */  protected void doGet(HttpServletRequest req, HttpServletResponse resp)  throws ServletException,java.io.IOException  {    this.doPost(req,resp);  }  /**   * handles HTTP POST requests.  This method will execute in a separate thread   * within the servlet container's JVM.   *   * @param req an HttpServletRequest object that contains the request the   *        client has made of the servlet   * @param resp an HttpServletResponse object that contains the response the   *        servlet sends to the client   * @throw java.io.IOException if an input or output error is detected when   *        the servlet handles the request   * @throw ServletException - if the request for the POST could not be handled   */  protected void doPost(HttpServletRequest req,HttpServletResponse resp)  throws ServletException,java.io.IOException  {    String httpParam_requestType = null;  // http param sent by client    String httpParam_clickX = null;       // http param sent by client    String httpParam_clickY = null;       // http param sent by client    HttpSession clientSession = null;     // client's session object    MapJ mapj = null;                     // client's map-state object    try    {      // throw exception if NOT all servlet init params were loaded on startup.      // since this is the case, NO response will be sent back to the client.      if (!NaviServlet.m_allInitParamsLoaded)      {        throw new ServletException("SOME SERVLET INIT PARAMS ARE MISSING.");      }      // read http parameters sent by client      httpParam_requestType = req.getParameter(NaviServlet.m_param_requestType);      httpParam_clickX = req.getParameter(NaviServlet.m_param_screenClickX);      httpParam_clickY = req.getParameter(NaviServlet.m_param_screenClickY);      //------------------------------------------------------------------------      // if NO request type http param was sent, we will assume this is the      // client's FIRST request to this servlet      //------------------------------------------------------------------------      if (httpParam_requestType == null)