loginscreen.java

J2ME MIDP_Example_Applications

// Copyright 2002 Nokia Corporation. 
// 
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER, 
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// 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 
// 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 
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package example.delivery;

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


class LoginScreen
    extends Form
    implements CommandListener, HttpPosterListener
{
    private DeliveryMIDlet midlet;
    private HttpPoster httpPoster;
    private TextField usernameField;
    private TextField passwordField;
    private Command submitCommand;
    private Command cancelCommand;
    private boolean readyForInput = true;
    private boolean canStorePassword = false; // The default is to not store
                                              // passwords persistently.
    private Courier courier;


    LoginScreen(DeliveryMIDlet midlet, HttpPoster httpPoster)
    {
        super("Login");
        this.midlet = midlet;
        this.httpPoster = httpPoster;

        String username = null;
        String password = null;
        try
        {
            courier = Courier.getInstance();
            username = courier.getUsername();
            if (canStorePassword)
            {
                password = courier.getPassword();
            }
        }
        catch (RecordStoreException e)
        {
            // In the worst case, the user needs to remember their username
            // and password. Using saved information is just a convienence.
        }
        usernameField = new TextField("User", username, 16, TextField.ANY);
        append(usernameField);
        passwordField = new TextField("Password", password, 8, TextField.PASSWORD);
        append(passwordField);
        submitCommand = new Command("Submit", Command.OK, 1);
        addCommand(submitCommand);
        cancelCommand = new Command("Cancel", Command.CANCEL, 2);
        addCommand(cancelCommand);

        setCommandListener(this);
    }


    public void commandAction(Command c, Displayable d)
    {
        if (c == cancelCommand)
        {
            midlet.loginScreenCancel();
        }
        else if (readyForInput)
        {
            if (c == submitCommand)
            {
                String username = usernameField.getString();
                String password = passwordField.getString();

                // Remember the username/password for other MIDlet invocations.
                storeCourier(username, password);

                try
                {
                    sendLoginRequest(username, password);
                    readyForInput = false; // wait for HTTP response
                }
                catch (IOException e)
                {
                    ErrorScreen.showError("Communications error");
                }
            }
        }
    }


    private void storeCourier(String username, String password)
    {
        try
        {
            // Persistently save username (and possibly the password)
            // in the RecordStore. This saves the user from typing those
            // in every time the MIDlet is re-invoked.

            Courier courier = Courier.getInstance();
            courier.setUsername(username);
            if (canStorePassword) // depends on the MIDlet's security policy
            {
                courier.setPassword(password);
            }
        }
        catch (RecordStoreException e)
        {
            // In the worst case, the user needs to remember their username
            // and password. Saving such information is just a convienence.

            ErrorScreen.showError("RecordStore error :" + e.getMessage());
        }
    }


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


    public void setCanStorePassword(boolean canStorePassword)
    {
        this.canStorePassword = canStorePassword;
    }


    public void receiveHttpResponse(String responseStr)
    {
        ValueParser parser = new ValueParser(responseStr);
        String response = parser.getNextValue();
        if ("login-OK".equals(response))
        {
            midlet.loginScreenDone();
        }
        else if ("login-error".equals(response))
        {
            String errorMessage = parser.getNextValue();
            if (errorMessage != null)
            {
                midlet.loginScreenError(errorMessage);
            }
            else
            {
                midlet.loginScreenError("Server error");
            }
        }
        else
        {
            midlet.loginScreenError("Server error");
        }
        readyForInput = true;
    }


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