UIDReader.java
/*
* Copyright © 2011 Nokia Corporation. All rights reserved.
* Nokia and Nokia Connecting People are registered trademarks of Nokia Corporation.
* Oracle and Java are trademarks or registered trademarks of Oracle and/or its
* affiliates. Other product and company names mentioned herein may be trademarks
* or trade names of their respective owners.
* See LICENSE.TXT for license information.
*/
/**
* @author Gerald Madlmayr (original) & Forum Nokia
* @version 1.2
*
* MIDlet that reads the UID of a tag
*/
package com.nokia.example;
// Classes for contactless communication
import javax.microedition.contactless.ContactlessException;
import javax.microedition.contactless.DiscoveryManager;
import javax.microedition.contactless.TargetListener;
import javax.microedition.contactless.TargetProperties;
import javax.microedition.contactless.TargetType;
// Classes for UI
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.*;
public class UIDReader
extends MIDlet
implements TargetListener, CommandListener {
// Global variables for the UI
private Command exitCommand;
private Form form;
public UIDReader() {
// Create the UI
exitCommand = new Command("Exit", Command.EXIT, 1);
form = new Form("UIDReader");
form.addCommand(exitCommand);
form.setCommandListener(this);
form.append("Touch tag to read ID");
// Determine the contactless target types supported by the device
TargetType[] supportedTargetTypes = DiscoveryManager.getSupportedTargetTypes();
// Check if the NDEF_TAG type is supported by the device,
// and, if it is, register TargetListener for it
for (int i=0; i<supportedTargetTypes.length; i++) {
if (supportedTargetTypes[i].equals(TargetType.NDEF_TAG)) {
// Register TargetListener (this) for NDEF targets
try {
DiscoveryManager dm = DiscoveryManager.getInstance();
dm.addTargetListener(this, TargetType.NDEF_TAG);
} catch (SecurityException se) {
displayAlert("Unable to register TargetListener: " + se.toString(), AlertType.ERROR);
} catch (ContactlessException ce) {
displayAlert("Unable to register TargetListener: " + ce.toString(), AlertType.ERROR);
} catch (IllegalStateException ise) {
displayAlert("Unable to register TargetListener: " + ise.toString(), AlertType.ERROR);
} catch (NullPointerException npe) {
displayAlert("Unable to register TargetListener: " + npe.toString(), AlertType.ERROR);
}
// Break the loop, since a matching target type has been found
break;
}
}
}
public void startApp() {
Display.getDisplay(this).setCurrent(form);
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
/**
* Implements the callback function of TargetListener
* @param targetProperties: Array of targets found by the device
*/
public void targetDetected(TargetProperties[] targetProperties) {
// In case no targets are found, exit the method
if (targetProperties.length == 0) {
return;
}
// Read and display the UID of the first target found
TargetProperties tmp = targetProperties[0];
displayAlert("UID read: " + tmp.getUid(), AlertType.INFO);
}
/**
* Implements the callback function of CommandListener
* @param command: Command given
* @param displayable: Associated Displayable object
*/
public void commandAction(Command command, Displayable displayable) {
if (command == exitCommand) {
DiscoveryManager dm = DiscoveryManager.getInstance();
dm.removeTargetListener(this, TargetType.NDEF_TAG);
destroyApp(false);
notifyDestroyed();
}
}
private void displayAlert(String error, AlertType type) {
Alert err = new Alert(form.getTitle(), error, null, type);
Display.getDisplay(this).setCurrent(err, form);
}
}