import com.pi4j.component.switches.SwitchState; //导入依赖的package包/类
/**
 * Constructs a software representation of a PiFace button.
 * 
 * @param piFaceSwitch
 *            the switch of the PiFace to use.
 * @throws IOException
 */
public PiFaceButton(PiFace piface, PiFaceSwitch piFaceSwitch) throws IOException {

	// add a listener with the pi4j library to hide the library
	piface.getSwitch(piFaceSwitch).addListener(new SwitchListener() {

		@Override
		public void onStateChange(SwitchStateChangeEvent event) {
			if (event.getNewState() == SwitchState.ON) {
				setState(ButtonState.ON);
			} else {
				setState(ButtonState.OFF);
			}
		}
	});
}