This appendix shows two examples how to communicate with RFID tag. In the first example the communication is done using PlainTagConnection interface. The second example is a reference example of the communication using target-specific connection provided by the API implementation.

PlainTagConnection example

/**
 * RFID reader MIDlet
 */
public class PlainTagMIDlet extends MIDlet implements TargetListener {

    private DiscoveryManager dm;
    
    public PlainTagMIDlet() {
        // Register TargetListener
        dm = DiscoveryManager.getInstance();
        try {
            dm.addTargetListener(this,TargetType.RFID_TAG);
        }
        catch (ContactlessException ce) {
            // handle exception
        }
    }

    // Target discovered
    public void targetDetected(TargetProperties[] props) {
        TargetProperties target = null;
        
        // Select target that has the right mapping
        for (int i = 0; i < props.length; i++) {
            if (props[i].getMapping().equals("MyMapping")) {
                target = props[i];
                break;
            }
            else {
                i++;
            }
        }
		
        // right target found 
        if (target != null) {
            // do the communication in separate thread
            MyThread thread = new MyThread(target);
            thread.start();
        }
    }
    . . .
}
	
/**
 * RFID reader thread
 */	
public class MyThread extends Thread {

    private TargetProperties target;
    
    public MyThread(TargetProperties target) {
        this.target = target;
    }
    
    public void run() {
        try {
            PlainTagConnection pconn = 
              (PlainTagConnection)Connector.open(target.getUrl());
            Vector input = new Vector();
            Vector output = new Vector();
            String cmd = new String( "read" );
            Integer sector = new Integer(2);
            Integer block = new Integer(1);
            byte[] key = {(byte)0x1, (byte)0x2, (byte)0x3,
                          (byte)0x4, (byte)0x5, (byte)0x6,
                          (byte)0x7};
            byte[] dataRead = new byte[16];
            byte[] accessBits = new byte[4];
            input.addElement( cmd );
            input.addElement( sector );
            input.addElement( block );
            input.addElement( key );
            output.addElement( dataRead );
            output.addElement( accessBits );
            output = pconn.transceive(input);          
            pconn.close();
            
            // Process the data
          }
          catch (IOException ioe) {
            // Handle exception
          }
          catch (ContactlessException ce) {
            // handle exception
          }
    }
}
	

Target-specific connection example

In this example the target-specific connection class used is only an imaginary example and not specified in this specification. It is only used to illustrate how the use of target-specific connection classes provided by the API implementation can make the communication with the RFID tag a bit easier.

/**
 * RFID reader MIDlet
 */
public class PlainTagMIDlet extends MIDlet implements TargetListener {

    private DiscoveryManager dm;
    
    public PlainTagMIDlet() {
        dm = DiscoveryManager.getInstance();
        try {
            dm.addTargetListener(this,TargetType.RFID_TAG);
        }
        catch (ContactlessException ce) {
            // handle exception
        }
    }

    public void targetDetected(TargetProperties[] props) {
        TargetProperties target = null;
		
        if (props.length > 1) {
            // Multiple targets found, exit
            return;
        }      
        target = props[0];

        // right target found 
        if (target != null) {
            // do the communication in separate thread
            MyThread thread = new MyThread(target);
            thread.start();
        }
    }
    . . . 
}
		

/**
 * RFID reader thread
 */	
public class MyThread extends Thread {

    private TargetProperties target;
    
    public MyThread(TargetProperties target) {
        this.target = target;
    }
    
    public void run() {

        Class[] connections = target.getConnectionNames();
        Class connClass = null;
        for (int i = 0; i < connections.length; i++) {
            if (connections[i].getName().equals
                    ("com.company.JSRTagConnection")) {
                // Right connection name found
                connClass = connections[i];
                break;
            }
            else {
                i++;
            }
        }
          
        if (connClass != null) {
            try {
                JSRTagConnection conn = (JSRTagConnection)
                    Connector.open(target.getUrl(connClass));
                int sector = 2;
                int block = 1;
                byte[] key = {(byte)0x1, (byte)0x2, (byte)0x3,
                    (byte)0x4, (byte)0x5, (byte)0x6,(byte)0x7};
                byte ret = conn.authenticate(sector, key);
                if (ret == 0) {
                    ret = conn.writeData(block, "Hello world");
                    String data = conn.readData(block);
                    // Process the data
                }
                conn.close();
            }
            catch (IOException ioe) {
                // Handle exception
            }
        }
    }
}