Programming Languages Suite/ProgLangD.iso/VCAFE.3.0A/Sample.bin/ESDServlet.java

Java Source | 1998-10-17 | 6.0 KB | 234 lines

package symantec.sourcebook.servlet;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ESDServlet extends HttpServlet
{

   // constants for pages and their numbers

    protected static int NOFORM_PAGE_NUM = 0;
    protected static int ENTERINFO_PAGE_NUM = 1;
    protected static int VERIFYINFO_PAGE_NUM = 2;
    protected static int OWNER_PAGE_NUM = 3;
    protected static int DOWNLOAD_PAGE_NUM = 4;
    protected static int SUCCESS_PAGE_NUM = 5;
    protected static int ERROR_PAGE_NUM = 6;

    /**
     *  Class names of the classes that handle each page.
     *
     */
    public  String[] pageHandlerNames =  {
                            "symantec.sourcebook.servlet.PHNoForm",
                            "symantec.sourcebook.servlet.PHEnterInfo",
                            "symantec.sourcebook.servlet.PHVerifyInfo",
                            "symantec.sourcebook.servlet.PHOwner",
                            "symantec.sourcebook.servlet.PHDownload",
                            "symantec.sourcebook.servlet.PHSuccess",
                            "symantec.sourcebook.servlet.PHError"};





    /**
     * Returns a brief description of this servlet.
     * Typically used by servlet administrative functions.
     *
     */

    public String getServletInfo()
    {
        return "Sample ESD servlet";
    }

    public void doGet(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
    {
        // handle the GET the same way we handle POSTS

        doPost(req,resp);

    }

    /**
     * Handle client POST request.
     * This is the main function of this servlet.
     * It determines the page being POSTed,
     * obtains the PageHandler for the page.  Calls
     * the PageHandler to validate the page.  Calls
     * the PageHandler to obtain the next page to be served
     * and serves it.
     *
     *
     */

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
    {

         // don't accept giant posts, they're either errors or bogus

        if(req.getContentLength() > 4096)
        {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return;
        }

        // determine which form has been submitted

        int pageNumber = getPageNumber(req);

        // get handler for that page

        PageHandler pageHandler = getPageHandler(pageNumber);

        // validate the contents of the form

        Object pageData = pageHandler.validate(getServletConfig(),req,resp);

        // Ask the page handler what page should be served
        // next (often determined in validate)

        pageNumber = pageHandler.nextPage();

        // get the page handler for the next page to be served...

        pageHandler = getPageHandler(pageNumber);

        // ...and serve it up

        pageHandler.serve(pageData,resp);



    }

    /**
     * This method obtains the page handler for the specified page number.
     *
     */

    protected PageHandler getPageHandler(int pageNumber) throws ServletException
    {


        // get the name of the class that handles this page number
        // this will be a subclass of PageHandler

        String pageHandlerName = pageHandlerNames[pageNumber];


        try
        {
            // instantiate the handler for this page

            PageHandler pageHandler = (PageHandler)(Class.forName(pageHandlerName)).newInstance();

            return pageHandler;
         }
        catch(Exception e)
        {

        }


        // some sort of exception occured trying to instantiate
        throw new ServletException("(Order) Internal servlet error (1)");

    }



    // perform one-time servlet initialization

    public  void  init(ServletConfig config) throws ServletException
    {
        // perform standard init
        super.init(config);

        // try to initialize the recent transaction info

        try
        {
            Transaction.InitializeTransactions();
        }
          catch(Exception e)
        {
            // Some exception occured. Let server know that this servlet is unavailable.

            UnavailableException u = new UnavailableException(this,e + " " + e.getMessage());
            throw u;
        }
    }

    // perform one-time servlet shutdonw

    public void destroy()
    {
        try
        {
            Transaction.WriteTransactions();
        }
        catch(IOException e)
        {
        }

        super.destroy();
    }


    /**
     * Return the current page number. This number is embeded in a hidden
     * field on each of the pages served.
     */

    public int getPageNumber(HttpServletRequest request)
    {

            int pageNumber = NOFORM_PAGE_NUM;

            // obtain the value of the "page" field on the current form

            String pageString = request.getParameter("page");

            // if no page parameter is found, this is either
            // the initial request (so we should retrun page zero)
            // or it's a re-download request (so we should return
            // the re-download page.)

            if(pageString == null)
            {
                // we've set up the HTML so that the download page
                // has a specific URI... this allows the user to bookmark
                // the page and return there if the initial download attempt fails

                if(request.getRequestURI().startsWith("/servlet/purchase/down")) pageNumber = SUCCESS_PAGE_NUM;
                return pageNumber;
            }

            // ok, we have a page number, make sure its good and within
            // range. (It always should be unless we made an error on one
            // of our HTML forms, or a user has modified the form)

            try
            {
                pageNumber = Integer.parseInt(pageString);
                if(pageNumber >= pageHandlerNames.length) pageNumber = NOFORM_PAGE_NUM;
            }
            catch(NumberFormatException e)
            {
                pageNumber = NOFORM_PAGE_NUM;
            }


            return pageNumber;

    }



}