Bar Code Reader

BarcodeReader.java

import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Listener for reading data from the barcode Reader
 * @author Aravinda
 *
 */
public class BarcodeReader {

	private static final long THRESHOLD = 100;
	private static final int MIN_BARCODE_LENGTH = 8;

	public interface BarcodeListener {

		void onBarcodeRead(String barcode);
	}

	private final StringBuffer barcode = new StringBuffer();
	private final List<BarcodeListener> listeners = new CopyOnWriteArrayList<BarcodeListener>();
	private long lastEventTimeStamp = 0L;

	public BarcodeReader() {

		KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(
				new KeyEventDispatcher() {
					@Override
					public boolean dispatchKeyEvent(KeyEvent e) {
						
						if (e.getID() != KeyEvent.KEY_RELEASED) {
							return false;
						}

						if (e.getWhen() - lastEventTimeStamp > THRESHOLD) {
							barcode.delete(0, barcode.length());
						}

						lastEventTimeStamp = e.getWhen();

						if (e.getKeyCode() == KeyEvent.VK_ENTER) {
						 
							if (barcode.length() >= MIN_BARCODE_LENGTH) {
								fireBarcode(barcode.toString());
							}
							barcode.delete(0, barcode.length());
						} else {
							barcode.append(e.getKeyChar());
						}
						return false;
					}
				});

	}

	protected void fireBarcode(String barcode) {
		for (BarcodeListener listener : listeners) {
			listener.onBarcodeRead(barcode);
		}
	}

	public void addBarcodeListener(BarcodeListener listener) {
		listeners.add(listener);
	}

	public void removeBarcodeListener(BarcodeListener listener) {
		listeners.remove(listener);
	}

}

Sample Uasage...

BarcodeReader barcodeReader = new BarcodeReader();
        barcodeReader.addBarcodeListener(new BarcodeListener() {
            @Override
            public void onBarcodeRead(String barcode) {
                                    System.out.println("Bar Code Value : ",barcode);
            }
    });