Categories: Code Examples | Java | Near Field Communication (NFC)

This page was last modified 18:34, 20 May 2008.

From Forum Nokia Wiki

MIDlet to write and read Bluetooth NDEF tags. User can also search for Bluetooth devices MAC address and create a tag for it.

package com.nokia.nfc.sample.app;
 
import java.io.IOException;
import java.util.Vector;
 
import javax.bluetooth.BluetoothStateException;
import javax.bluetooth.DeviceClass;
import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.DiscoveryListener;
import javax.bluetooth.LocalDevice;
import javax.bluetooth.RemoteDevice;
import javax.bluetooth.ServiceRecord;
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;
import javax.microedition.contactless.ndef.NDEFMessage;
import javax.microedition.contactless.ndef.NDEFRecord;
import javax.microedition.contactless.ndef.NDEFRecordType;
import javax.microedition.contactless.ndef.NDEFTagConnection;
import javax.microedition.io.Connector;
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.lcdui.List;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
 
/**
 * MIDlet to write and read Bluetooth NDEF tags. User can also search for
 * Bluetooth devices MAC address and create a tag for it.
 */
public class BtNdefManager extends MIDlet implements TargetListener,
        CommandListener, DiscoveryListener {
 
    private Display display;
    private Form form;
    private TextField configTypeTf;
    private TextField btAddtessTf;
    private TextField btClassTf;
    private TextField authInfoTf;
    private TextField shortNameTf;
    private Command writeCmd;
    private Command cancelCmd;
    private Command discoverCmd;
    private Command selectCmd;
    private Command exitCmd;
 
    private DiscoveryAgent discoveryAgent;
    private Vector devices;
 
    private List deviceList;
 
    // Boolean to tell if MIDlet is on writing mode
    private boolean write = false;
 
    protected void destroyApp(boolean unconditional)
            throws MIDletStateChangeException {
    }
 
    protected void pauseApp() {
    }
 
    protected void startApp() throws MIDletStateChangeException {
        // Get instance of NFC Discovery Manager
        DiscoveryManager dm = DiscoveryManager.getInstance();
 
        // Register NDEF_TAG target to discovery
        try {
            dm.addTargetListener(this, TargetType.RFID_TAG);
        } catch (IllegalStateException e) {
            // Catch IllegalStateException
        } catch (ContactlessException e) {
            // Catch ContactlessException
        }
 
        // Initialize and show user interface elements
        display = Display.getDisplay(this);
        form = new Form("ReadSerial");
 
        configTypeTf = new TextField("configType:", "00", 2, TextField.ANY);
        btAddtessTf = new TextField("btAddtess:", "", 12, TextField.ANY);
        btClassTf = new TextField("btClass:", "000680", 6, TextField.ANY);
        authInfoTf = new TextField("authInfo:",
                "00000000000000000000000000000000", 32, TextField.ANY);
        shortNameTf = new TextField("shortName:", "BT", 255, TextField.ANY);
 
        form.append(configTypeTf);
        form.append(btAddtessTf);
        form.append(btClassTf);
        form.append(authInfoTf);
        form.append(shortNameTf);
 
        writeCmd = new Command("Write", Command.OK, 1);
        cancelCmd = new Command("Cancel", Command.CANCEL, 1);
        discoverCmd = new Command("Discover", Command.ITEM, 1);
        selectCmd = new Command("Select", Command.OK, 1);
        exitCmd = new Command("Exit", Command.EXIT, 1);
        form.addCommand(writeCmd);
        form.addCommand(discoverCmd);
        form.addCommand(exitCmd);
        form.setCommandListener(this);
        display.setCurrent(form);
    }
 
    public void targetDetected(TargetProperties[] properties) {
        if (!write) {
            // Read
            NDEFTagConnection conn = null;
            try {
                conn = (NDEFTagConnection) Connector.open(properties[0]
                        .getUrl());
 
                NDEFMessage message = conn.readNDEF();
                if (message != null) {
                    NDEFRecord[] records = message.getRecords();
                    for (int i = 0; i < records.length; i++) {
                        byte[] record = records[i].toByteArray();
 
                        byte[] typeName = new byte[12];
                        System.arraycopy(record, 3, typeName, 0, 12);
 
                        byte[] configType = new byte[] { record[15] };
 
                        byte[] btAddtess = new byte[6];
 
                        System.arraycopy(record, 16, btAddtess, 0, 6);
 
                        byte[] btClass = new byte[3];
                        System.arraycopy(record, 22, btClass, 0, 3);
 
                        byte[] authInfo = new byte[16];
                        System.arraycopy(record, 25, authInfo, 0, 16);
 
                        byte[] shortName = new byte[record[41]];
                        System.arraycopy(record, 42, shortName, 0, record[41]);
 
                        configTypeTf.setString(toHexString(configType));
                        btAddtessTf.setString(toHexString(btAddtess));
                        btClassTf.setString(toHexString(btClass));
                        authInfoTf.setString(toHexString(authInfo));
                        shortNameTf.setString(new String(shortName));
 
                    }
                } else {
                    // No BT record found
                }
            } catch (Exception e) {
            } finally {
                try {
                    if (conn != null) {
                        conn.close();
                    }
                } catch (IOException e) {
                }
            }
 
        } else {
            // Write
            NDEFTagConnection conn = null;
            try {
                conn = (NDEFTagConnection) Connector.open(properties[0]
                        .getUrl());
                byte payLoad[] = new byte[1 + 6 + 3 + 16 + 1
                        + shortNameTf.size()];
 
                System.arraycopy(toByteArray(configTypeTf.getString()), 0,
                        payLoad, 0, 1);
                System.arraycopy(toByteArray(btAddtessTf.getString()), 0,
                        payLoad, 1, 6);
                System.arraycopy(toByteArray(btClassTf.getString()), 0,
                        payLoad, 7, 3);
                System.arraycopy(toByteArray(authInfoTf.getString()), 0,
                        payLoad, 10, 16);
                payLoad[26] = (byte) shortNameTf.size();
                System.arraycopy(shortNameTf.getString().getBytes(), 0,
                        payLoad, 27, shortNameTf.size());
 
                NDEFRecord[] records = new NDEFRecord[] { new NDEFRecord(
                        new NDEFRecordType(NDEFRecordType.EXTERNAL_RTD,
                                "urn:nfc:ext:nokia.com:bt"), null, payLoad) };
                NDEFMessage message = new NDEFMessage(records);
                conn.writeNDEF(message);
                form.append("Written");
 
                form.removeCommand(cancelCmd);
                form.addCommand(writeCmd);
                write = false;
                display.setCurrent(new Alert("Alert", "Written", null,
                        AlertType.INFO), form);
            } catch (ContactlessException e) {
                form.append(e.toString());
            } catch (IOException e) {
                form.append(e.toString());
            } finally {
                if (conn != null) {
                    try {
                        conn.close();
                    } catch (IOException e) {
                    }
                }
            }
        }
 
    }
 
    private static String toHexString(byte[] value) {
        if (value == null)
            return "null";
 
        StringBuffer result = new StringBuffer();
 
        for (int i = 0; i < value.length; i++) {
            result.append(Integer.toHexString(value[i] >>> 4 & 0x0F));
            result.append(Integer.toHexString(value[i] & 0xF));
        }
        return result.toString();
    }
 
    private static byte[] toByteArray(String string) {
        if (string.length() % 2 != 1) {
            byte[] result = new byte[string.length() / 2];
            for (int i = 0; i < result.length; i++) {
                result[i] = (byte) Integer.parseInt(string.substring(2 * i,
                        2 * i + 2), 16);
            }
            return result;
        } else {
            return null;
        }
    }
 
    public void commandAction(Command c, Displayable d) {
 
        if (d == form) {
            if (c == cancelCmd || c == writeCmd) {
                if (write) {
                    form.removeCommand(cancelCmd);
                    form.addCommand(writeCmd);
                } else {
                    form.removeCommand(writeCmd);
                    form.addCommand(cancelCmd);
                }
                write = !write;
            } else if (c == discoverCmd) {
                write = false;
                form.removeCommand(cancelCmd);
                form.removeCommand(writeCmd);
                form.removeCommand(discoverCmd);
                btSearch();
            } else if (c == exitCmd) {
                notifyDestroyed();
            }
        } else if (d == deviceList) {
            if (c == selectCmd) {
                RemoteDevice btDevice = (RemoteDevice) devices
                        .elementAt(deviceList.getSelectedIndex());
                btAddtessTf.setString(btDevice.getBluetoothAddress());
                form.removeCommand(cancelCmd);
                form.removeCommand(writeCmd);
                form.addCommand(writeCmd);
                form.addCommand(discoverCmd);
                display.setCurrent(form);
            } else if (c == cancelCmd) {
                write = false;
                discoveryAgent.cancelInquiry(this);
                form.removeCommand(cancelCmd);
                form.addCommand(writeCmd);
                form.addCommand(discoverCmd);
                display.setCurrent(form);
            }
        }
 
    }
 
    // Starts the search for the Bluetooth devices
    private void btSearch() {
 
        // Set the right UI
        deviceList = new List("Searcing devices", List.IMPLICIT);
        deviceList.setSelectCommand(selectCmd);
        deviceList.addCommand(cancelCmd);
        deviceList.setCommandListener(this);
        display.setCurrent(deviceList);
 
        devices = new Vector();
        // Start an inquiry to find Bluetooth devices
        try {
            LocalDevice local = LocalDevice.getLocalDevice();
            discoveryAgent = local.getDiscoveryAgent();
            discoveryAgent.startInquiry(DiscoveryAgent.GIAC, this);
 
        } catch (BluetoothStateException e) {
        }
    }
 
    public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {
        // When device has been found add it to devices Vector..
        devices.addElement(btDevice);
 
        // .. and to the deviceList List
        String devName;
        try {
            devName = btDevice.getFriendlyName(false);
 
            if (devName == null || devName.compareTo("") == 0) {
                devName = btDevice.getBluetoothAddress();
            }
            deviceList.append(devName, null);
        } catch (IOException e) {
        }
    }
 
    public void inquiryCompleted(int arg0) {
        // When searching of the devices has completed set title to indicate
        // that
        deviceList.setTitle("Inquiry completed");
    }
 
    public void serviceSearchCompleted(int arg0, int arg1) {
    }
 
    public void servicesDiscovered(int arg0, ServiceRecord[] arg1) {
    }
 
}