Atm Status Finite State Machine Example using Apache Commons SCXML Library

atm_status.xml

<scxml initial="idle" name="atm.connRestored" version="0.9" 
	xmlns="http://www.w3.org/2005/07/scxml">
	
 <state id="idle">
  <transition event="atm.connected" target="loading"></transition>
 </state>
 
 <state id="loading">
  <transition event="atm.loadSuccess" target="inService"></transition>
  <transition event="atm.connClosed" target="disconnected"></transition>
  <transition event="atm.loadFail" target="outOfService"></transition>
 </state>
 
 <state id="inService">
  <transition event="atm.shutdown" target="outOfService"></transition>
  <transition event="atm.connLost" target="disconnected"></transition>
 </state>
 
 <state id="outOfService">
  <transition event="atm.startup" target="inService"></transition>
  <transition event="atm.connLost" target="disconnected"></transition>
 </state>
 
 <state id="disconnected">
  <transition event="atm.connRestored" target="inService"></transition>
 </state>
 
</scxml>

AtmDisplay.java

package net.javafun.example.atmstatusfsm;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

import org.apache.commons.scxml.model.Transition;

/**
 * Atm Status Change GUI
 * 
 * @author ozkansari.com
 *
 */
public class AtmDisplay extends JFrame implements ActionListener {

 private static final long serialVersionUID = -5083315372455956151L;
 private AtmStatusFSM atmStatusFSM;

 private JButton button;
 private JLabel state;
 private JComboBox eventComboBox = new JComboBox();
 
 public static void main(String[] args) {
  new AtmDisplay();
 }
 
 public AtmDisplay() {
  super("ATM Display Demo");
  atmStatusFSM = new AtmStatusFSM();
  setupUI();
 }

 @SuppressWarnings("deprecation")
 private void setupUI() {
  JPanel panel = new JPanel();
  panel.setLayout(new BorderLayout());
  setContentPane(panel);
  button = makeButton("FIRE_EVENT", AtmStatusEventEnum.getNamesAsCsv(), "Submit" );
  panel.add(button, BorderLayout.CENTER);
  state = new JLabel(atmStatusFSM.getCurrentStateId());
  panel.add(state, BorderLayout.SOUTH);
  initEvents();
  panel.add(eventComboBox, BorderLayout.NORTH);
  pack();
  setLocation(200, 200);
  setResizable(false);
  setSize(300, 125);
  show();
  setDefaultCloseOperation(EXIT_ON_CLOSE);
  
 }

 @SuppressWarnings("unchecked")
 private void initEvents() {
  eventComboBox.removeAllItems();
  List transitionList = atmStatusFSM.getCurrentState().getTransitionsList();
  for (Transition transition : transitionList) {
   eventComboBox.addItem(transition.getEvent() );
  }
 }

 public void actionPerformed(ActionEvent e) {
  String command = e.getActionCommand();
  if(command.equals("FIRE_EVENT")) {
   checkAndFireEvent();
  }
 }

 private boolean checkAndFireEvent() {
  atmStatusFSM.fireEvent(eventComboBox.getSelectedItem().toString());
  state.setText(atmStatusFSM.getCurrentStateId());
  initEvents();
  repaint();
  return true;
 }

 private JButton makeButton(final String actionCommand, final String toolTipText, final String altText) {
  JButton button = new JButton(altText);
  button.setActionCommand(actionCommand);
  button.setToolTipText(toolTipText);
  button.addActionListener(this);
  button.setOpaque(false);
  return button;
 }

}

AtmStatusEventEnum.java

package net.javafun.example.atmstatusfsm;

/**
 * Atm Status Change Events
 * 
 * @author ozkansari.com
 *
 */
public enum AtmStatusEventEnum {

 CONNECT("atm.connected"), 
 
 CONNECTION_CLOSED("atm.connClosed"),
 
 CONNECTION_LOST("atm.connLost"),
 
 CONNECTION_RESTORED("atm.connRestored"),
 
 LOAD_SUCCESS("atm.loadSuccess"),
 
 LOAD_FAIL("atm.loadFail"),
 
 SHUTDOWN("atm.shutdown"),
 
 STARTUP("atm.startup");

 private final String eventName;

 private AtmStatusEventEnum(String eventName) {
  this.eventName = eventName;
 }
 
 public String getEventName() {
  return eventName;
 }
 
 public static String getNamesAsCsv(){
  StringBuilder sb = new StringBuilder();
  for (AtmStatusEventEnum e : AtmStatusEventEnum.values()) {
   sb.append(e.name());
   sb.append(",");
  }
  return sb.substring(0,sb.length()-2);
 }
 
}

AtmStatusFSM.java

package net.javafun.example.atmstatusfsm;

import java.util.Collection;
import java.util.Set;

import org.apache.commons.scxml.env.AbstractStateMachine;
import org.apache.commons.scxml.model.State;

/**
 * Atm Status Finite State Machine
 * 
 * @see  Apache Commons Scxml Library 
 * @author ozkansari.com
 *
 */
public class AtmStatusFSM extends AbstractStateMachine {

 /**
  * State Machine uses this scmxml config file
  */
 private static final String SCXML_CONFIG_ATM_STATUS = "net/javafun/example/atmstatusfsm/atm_status.xml";

 /* CONSTRUCTOR(S) */
 
 public AtmStatusFSM() {
   super(AtmStatusFSM.class.getClassLoader().getResource(SCXML_CONFIG_ATM_STATUS));
 }
 
 /* HELPER METHOD(S) */

 /*
  * Fire the event
  */
 public void firePreDefinedEvent(AtmStatusEventEnum eventEnum){
  System.out.println("EVENT: " + eventEnum);
  this.fireEvent(eventEnum.getEventName());
 }
 
 public void callState(String name){
  this.invoke(name);
 }
 
 /*
  * Get current state ID as string
  */
 public String getCurrentStateId() {
  Set states = getEngine().getCurrentStatus().getStates();
  State state = (State) states.iterator().next();
  return state.getId();
 }
 
 /*
  * Get current state as apache's State object
  */
 public State getCurrentState() {
  Set states = getEngine().getCurrentStatus().getStates();
  return ( (State) states.iterator().next());
 }
 
 /*
  * Get events belongs to current status of the FSM
  */
 public Collection getCurrentStateEvents() {
  return getEngine().getCurrentStatus().getEvents();
 }
 
 /* STATES */
 // Each method below is the activity corresponding to a state in the
 // SCXML document (see class constructor for pointer to the document).

 public void idle() {
  System.out.println("STATE: idle");
 }
  
 public void loading() {
   System.out.println("STATE: loading");
 }
  
 public void inService() {
   System.out.println("STATE: inService");
 }
  
 public void outOfService() {
   System.out.println("STATE: outOfService");
 }
  
 public void disconnected() {
   System.out.println("STATE: disconnected");
 }
}