loginscreen.java

利用javame开发的

// 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 
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// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED 
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// 
// 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. 
// 
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// Corporation.
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package example.fruitmachine;

import javax.microedition.lcdui.*;
import java.io.IOException;


class LoginScreen
    extends Form
    implements CommandListener, HttpPosterListener
{
    private final FruitMachineMIDlet midlet;
    private final HttpPoster httpPoster;
    private final TextField usernameField;
    private final TextField passwordField;
    private final Command quitCommand;
    private final Command loginCommand;
    private volatile boolean readyForInput = true;


    LoginScreen(FruitMachineMIDlet midlet,
                HttpPoster         httpPoster)
    {
        super("Fruit Machine");
        this.midlet = midlet;
        this.httpPoster = httpPoster;

        usernameField = new TextField("User", null, 16, TextField.ANY);
        append(usernameField);
        passwordField = new TextField("Password", null, 8, TextField.PASSWORD);
        append(passwordField);
        quitCommand = new Command("Quit", Command.EXIT, 2);
        addCommand(quitCommand);
        loginCommand = new Command("Login", Command.SCREEN, 2);
        addCommand(loginCommand);

        setCommandListener(this);
    }

    
    public void commandAction(Command c, Displayable d)
    {
        if (c == quitCommand)
        {
            midlet.loginScreenQuit();
        }
        else if (readyForInput)
        {
            if (c == loginCommand)
            {
                try
                {
                    sendLoginRequest(usernameField.getString(),
                                     passwordField.getString());
                    readyForInput = false;
                }
                catch (IOException e)
                {
                    ErrorScreen.showError("Communications error");
                }
            }
        }
    }


    private void sendLoginRequest(String username, String password)
        throws IOException
    {
        ValueGenerator generator = new ValueGenerator();
        generator.addValue("login");
        generator.addValue(username);
        generator.addValue(password);
        String dataStr = generator.getString();
        httpPoster.sendRequest(dataStr, this);
    }


    public void receiveHttpResponse(String responseStr)
    {
        ValueParser parser = new ValueParser(responseStr);
        String response = parser.getNextValue();
        if ("login-OK".equals(response))    // no harm if response is null
        {
            try
            {
                String creditStr = parser.getNextValue();
                int credit = Integer.parseInt(creditStr);
                Account account= new Account(credit);
                midlet.loginScreenDone(account);
            }
            catch (NumberFormatException e)
            {
                ErrorScreen.showError("Server error");
            }
        }
        else if ("login-error".equals(response))
        {
            String errorMessage = parser.getNextValue();
            if (errorMessage != null)
            {
                ErrorScreen.showError(errorMessage);
            }
            else
            {
                ErrorScreen.showError("Server error");
            }
        }
        else
        {
            ErrorScreen.showError("Server error");
        }
        readyForInput = true;
    }


    public void handleHttpError(String errorStr)
    {
        ErrorScreen.showError("Error communicating with server");
        readyForInput = true;
    }
}