gameprotocolhandler.java

J2ME MIDP_Example_Applications

// Copyright 2002 Nokia Corporation. 
// 
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER, 
// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS 
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE 
// OR TRADE PRACTICE, RELATING TO THE SOURCE CODE OR ANY WARRANTY OTHERWISE 
// ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE AND WITH NO 
// OBLIGATION OF NOKIA TO PROVIDE THE LICENSEE WITH ANY MAINTENANCE OR 
// SUPPORT. FURTHERMORE, NOKIA MAKES NO WARRANTY THAT EXERCISE OF THE 
// RIGHTS GRANTED HEREUNDER DOES NOT INFRINGE OR MAY NOT CAUSE INFRINGEMENT 
// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED 
// BY THIRD PARTIES 
// 
// Furthermore, information provided in this source code is preliminary, 
// and may be changed substantially prior to final release. Nokia Corporation 
// retains the right to make changes to this source code at 
// any time, without notice. This source code is provided for informational 
// purposes only. 
// 
// Nokia and Nokia Connecting People are registered trademarks of Nokia
// Corporation.
// Java and all Java-based marks are trademarks or registered trademarks of
// Sun Microsystems, Inc.
// Other product and company names mentioned herein may be trademarks or
// trade names of their respective owners.
// 
// A non-exclusive, non-transferable, worldwide, limited license is hereby 
// granted to the Licensee to download, print, reproduce and modify the 
// source code. The licensee has the right to market, sell, distribute and 
// make available the source code in original or modified form only when 
// incorporated into the programs developed by the Licensee. No other 
// license, express or implied, by estoppel or otherwise, to any other 
// intellectual property rights is granted herein.


package example.fruitmachine;

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


class GameProtocolHandler 
{
    static class InvalidRequestException
        extends Exception
    {
        InvalidRequestException(String message)
        {
            super(message);
        }

        InvalidRequestException()
        {
            super();
        }
    }


    private final UserDatabase userDatabase;


    GameProtocolHandler(UserDatabase userDatabase)
    {
        this.userDatabase = userDatabase;
    }


    void doPost(HttpServletRequest  request,
                HttpServletResponse response)
        throws IOException, ServletException
    {
        String requestStr = getRequestString(request);

        ValueGenerator generator = new ValueGenerator();
        ValueParser parser = new ValueParser(requestStr);
        String command   = parser.getNextValue();
        if ("login".equals(command))
        {
            handleLoginRequest(parser, generator, request, response);
        }
        else
        {
            HttpSession session = request.getSession(false);
            if (session == null)
            {
                throw new IOException("Must login");
            }
            else if ("spin".equals(command))
            {
                handleSpinRequest(parser, generator, session);
            }
            else if ("buy".equals(command))
            {
                handleBuyRequest(parser, generator, session);
            }
            else if ("logout".equals(command))
            {
                handleLogoutRequest(generator, session);
            }
            else
            {
                throw new IOException("Invalid command");
            }
        }
            

        String responseStr = generator.getString();
        setResponseString(response, responseStr);
    }


    private String getRequestString(HttpServletRequest request)
        throws IOException
    {
        InputStream in = request.getInputStream();
        int requestLength = request.getContentLength();
        if (requestLength == -1)
        {
            throw new IOException("Need to know request length");
        }
        StringBuffer buf = new StringBuffer(requestLength);
        for (int i = 0; i < requestLength; ++i)
        {
            int ch = in.read();
            if (ch == -1)
            {
                break;
            }
            buf.append((char)ch);
        }
        in.close();

        return buf.toString();
    }


    private void setResponseString(HttpServletResponse response,
                                   String responseStr)
        throws IOException
    {
        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();
        out.write(responseStr);
        out.close();
    }


    private void handleLoginRequest(ValueParser parser,
                                    ValueGenerator generator,
                                    HttpServletRequest request,
                                    HttpServletResponse response)
    {
        try
        {
            String name = getStringValue(parser);
            String password = getStringValue(parser);
            if ((name == null) || (name.length() == 0) )
            {
                throw new InvalidRequestException("Missing name");
            }
            else if (password == null)    // length 0 is OK
            {
                throw new InvalidRequestException("Missing password");
            }
            else
            {
                User user = userDatabase.getUser(name);
                if ((user == null) || !user.isCorrectPassword(password))
                {
                    throw new InvalidRequestException(
                        "Name or password incorrect");
                }
                else
                {
                    FruitMachine fruitMachine = new FruitMachine(user);
                    HttpSession session = request.getSession(true);
                    session.setAttribute("User", user);
                    session.setAttribute("FruitMachine", fruitMachine);

                    String requestUrl = request.getRequestURL().toString();
                    String rewrittenUrl = response.encodeURL(requestUrl);
                    response.setHeader("X-RewrittenURL", rewrittenUrl);

                    generator.addValue("login-OK");
                    generator.addValue(Integer.toString(user.getCredit()));
                }
            }
        }
        catch (InvalidRequestException e)
        {
            generateErrorResponse(generator, "login-error", e.getMessage());
        }
    }


    private void generateErrorResponse(ValueGenerator generator,
                                       String errorName,
                                       String message)
    {
        generator.addValue(errorName);
        generator.addValue(message);
    }


    private void handleSpinRequest(ValueParser parser,
                                   ValueGenerator generator,
                                   HttpSession session)
    {
        try
        {
            User user = (User)(session.getAttribute("User"));
            FruitMachine fruitMachine =
                (FruitMachine)(session.getAttribute("FruitMachine"));

            int bet = getIntValue(parser);
            boolean hold0 = getBooleanValue(parser);
            boolean hold1 = getBooleanValue(parser);
            boolean hold2 = getBooleanValue(parser);

            FruitMachine.SpinResult result =
                fruitMachine.spin(bet, hold0, hold1, hold2);

            if (result.isWin())
            {
                generator.addValue("spin-win");
                generator.addValue(Integer.toString(result.getWinAmount()));
            }
            else
            {
                generator.addValue("spin-lose");
            }
            generator.addValue(Integer.toString(user.getCredit()));
            generator.addValue(Integer.toString(result.getWheel(0)));
            generator.addValue(Integer.toString(result.getWheel(1)));
            generator.addValue(Integer.toString(result.getWheel(2)));
        }
        catch (FruitMachine.InvalidPlayException e)
        {
            generateErrorResponse(generator, "spin-error", e.getMessage());
        }
        catch (InvalidRequestException e)
        {
            generateErrorResponse(generator, "spin-error", e.getMessage());
        }
    }


    private void handleBuyRequest(ValueParser parser,
                                  ValueGenerator generator,
                                  HttpSession session)
    {
        try
        {
            User user = (User)(session.getAttribute("User"));
            
            int amount = getIntValue(parser);

            // this should go off to credit card issuer etc.
            user.addCredit(amount);

            generator.addValue("buy-OK");
            generator.addValue(Integer.toString(user.getCredit()));
        }
        catch (InvalidRequestException e)
        {
            generateErrorResponse(generator, "buy-error", e.getMessage());
        }
    }


    private void handleLogoutRequest(ValueGenerator generator,
                                     HttpSession session)
    {
        session.invalidate();

        generator.addValue("logout-OK");
    }


    private String getStringValue(ValueParser parser)
        throws InvalidRequestException
    {
        String value = parser.getNextValue();
        if (value == null)
        {
            throw new InvalidRequestException("Missing value");
        }
        return value;
    }


    private int getIntValue(ValueParser parser)
        throws InvalidRequestException
    {
        String valueStr = getStringValue(parser);
        int value;
        try
        {
            value = Integer.parseInt(valueStr);
        }
        catch (NumberFormatException e)
        {
            throw new InvalidRequestException("Value \"" + valueStr +
                                              "\" is not a valid integer");
        }                             
        return value;
    }


    private boolean getBooleanValue(ValueParser parser)
        throws InvalidRequestException
    {
        String valueStr = getStringValue(parser);
        boolean value = false;
        if (valueStr.equals("true"))
        {
            value = true;
        }
        else if (valueStr.equals("false"))
        {
            value = false;
        }
        else
        {
            throw new InvalidRequestException("Value \"" + valueStr +
                                              "\" is not a valid boolean");
        }
        return value;
    }
}