Apache Commons-SCXML系列之Demo：秒表

1 编程方式一

1.1 画状态图

秒表的状态图，其中秒表有：重置，运行中，**已停止**3个状态

1.2 编写xml文件

秒表状态机定义文件：stopwatch1.xml，xml文件分析请看后面

<?xml version="1.0"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0"initial="reset"><state id="reset"><onentry><script>stopWatchEntity.reset()</script></onentry><transition event="watch.start" target="running" /></state><state id="running"><onentry><script>stopWatchEntity.run()</script></onentry><transition event="watch.stop" target="stopped" /></state><state id="stopped"><onentry><script>stopWatchEntity.stop()</script></onentry><transition event="watch.start" target="running" ></transition><transition event="watch.reset" target="reset" /></state></scxml>

1.3 编写程序控制状态转移

需要操作的实体类，用来约束秒表的行为：StopWatchEntity.java

package stopwatch;
import java.io.Serializable;
import java.util.Timer;
import java.util.TimerTask;public class StopWatchEntity implements Serializable {private static final long serialVersionUID = 1L;//时分秒private int hr;private int min;private int sec;//100毫秒private int fract;private transient Timer timer;/*** 重置当前状态机*/public synchronized void reset() {hr = min = sec = fract = 0;}/*** 运行秒表*/public synchronized void run() {if (timer == null) {timer = new Timer(true);//使用timer来定时执行，秒表计数，每100毫秒，执行一次increment方法timer.scheduleAtFixedRate(new TimerTask() {@Overridepublic void run() {increment();}}, 100, 100);}}/*** 停止秒表*/public synchronized void stop() {timer.cancel();timer = null;}/*** 得到当前秒表的时间* @return*/public synchronized String getDisplay() {return String.format("%d:%02d:%02d,%d", hr, min, sec, fract);}/*** 自增方法*/private synchronized void increment() {if (fract < 9) {fract++;} else {fract = 0;if (sec < 59) {sec++;} else {sec = 0;if (min < 59) {min++;} else {min = 0;hr++;}}}}
}

界面类：StopWatchFrame.java

/*** Created by zhengshouzi on 2015/11/20.*/
package stopwatch;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URL;
import java.util.Timer;
import java.util.TimerTask;import javax.swing.*;import org.apache.commons.scxml2.Context;
import org.apache.commons.scxml2.Evaluator;
import org.apache.commons.scxml2.SCXMLExecutor;
import org.apache.commons.scxml2.TriggerEvent;
import org.apache.commons.scxml2.env.SimpleErrorReporter;
import org.apache.commons.scxml2.env.jexl.JexlEvaluator;
import org.apache.commons.scxml2.io.SCXMLReader;
import org.apache.commons.scxml2.model.ModelException;
import org.apache.commons.scxml2.model.SCXML;public class StopWatchFrame extends JFrame implements ActionListener {private static final long serialVersionUID = 1L;private JLabel displayLabel;private JButton startButton;private JButton stopButton;private JButton resetButton;private SCXMLExecutor executor;private StopWatchEntity stopWatchEntity;public static void main(String[] args) {new StopWatchFrame();}public StopWatchFrame() {super("SCXML StopWatch");//初始化状态机initStopWatch();//初始化界面initUI();}/*** 监听器需要执行的方法，自动调用* @param event 事件源*/public void actionPerformed(ActionEvent event) {//得到绑定在每个按钮上的命令String command = event.getActionCommand();//对各个命令进行判断，在执行相应的内容try {if ("START".equals(command)) {//生成watch.start事件，将转到running状态executor.triggerEvent(new TriggerEvent("watch.start", TriggerEvent.SIGNAL_EVENT));//设置一些列按钮的可见性startButton.setEnabled(false);stopButton.setEnabled(true);resetButton.setEnabled(false);} else if ("STOP".equals(command)) {//生成watch.stop事件，将转到stoped状态executor.triggerEvent(new TriggerEvent("watch.stop", TriggerEvent.SIGNAL_EVENT));startButton.setEnabled(true);stopButton.setEnabled(false);resetButton.setEnabled(true);} else if ("RESET".equals(command)) {//生成watch.reset事件，将转到reset状态executor.triggerEvent(new TriggerEvent("watch.reset", TriggerEvent.SIGNAL_EVENT));startButton.setEnabled(true);stopButton.setEnabled(false);resetButton.setEnabled(false);}} catch (ModelException e) {e.printStackTrace();}}/*** 初始化秒表*/private void initStopWatch() {//得到资源文件路径final  URL STOPWATCH = this.getClass().getResource("stopwatch1.xml");//实例化数据模型解析器Evaluator evaluator = new JexlEvaluator();//实例化引擎executor = new SCXMLExecutor(evaluator, null, new SimpleErrorReporter());try {//加载资源文件,实例化到一个SCXML对象，两者之间一一对应SCXML scxml = SCXMLReader.read(STOPWATCH);//将这样的一个SCXML实例，作为状态机对象，传入到引擎里面。executor.setStateMachine(scxml);//设置引擎执行的根上下文Context rootContext = evaluator.newContext(null);final StopWatchEntity stopWatchEntity = new StopWatchEntity();rootContext.set("stopWatchEntity", stopWatchEntity);executor.setRootContext(rootContext);//设置当前对象this.stopWatchEntity = stopWatchEntity;//开始启动流程executor.go();}catch (Exception e){e.printStackTrace();}}/*** 初始化界面*/private void initUI() {JPanel mainPanel = new JPanel();mainPanel.setLayout(new BorderLayout());setContentPane(mainPanel);JPanel contentPanel = new JPanel();contentPanel.setLayout(new FlowLayout());displayLabel = new JLabel("0:00:00,000");displayLabel.setFont(new Font(Font.DIALOG,100,50));contentPanel.add(displayLabel, BorderLayout.CENTER);mainPanel.add(contentPanel, BorderLayout.CENTER);JPanel buttonPanel = new JPanel();buttonPanel.setLayout(new FlowLayout());startButton = createButton("START", "Start");buttonPanel.add(startButton);stopButton = createButton("STOP", "Stop");stopButton.setEnabled(false);buttonPanel.add(stopButton);resetButton = createButton("RESET", "Reset");resetButton.setEnabled(false);buttonPanel.add(resetButton);mainPanel.add(buttonPanel, BorderLayout.SOUTH);setLocation(250,300);setSize(400,200);setResizable(true);setVisible(true);Timer displayTimer = new Timer();displayTimer.scheduleAtFixedRate(new TimerTask() {@Overridepublic void run() {displayLabel.setText(stopWatchEntity.getDisplay());}}, 100, 100);setDefaultCloseOperation(EXIT_ON_CLOSE);}/*** 创建一个按钮* @param command 按钮的命令* @param text 按钮上的文本* @return 返回一个新建的按钮*/private JButton createButton(final String command, final String text) {JButton button = new JButton(text);button.setActionCommand(command);button.addActionListener(this);return button;}}

1.4 程序结果分析

程序界面类中的定时器一直在访问 StopWatchEntity的getDisplay属性，来得到秒表的值。我们通过Start,Stop,Reset来控制秒表的状态，在进入某一个状态机的时候，我们调用这个状态机根上下文设置的stopWatcheEntity对象相应的方法，来改变秒表的值。当秒表一直处于某一个状态的时候，我们又通过点击按钮来改变秒表的状态。

2 编程方式2

2.1 画状态图

图和方式一一样

2.2 编写状态图xml文件

stopwatch2.xml，这个类里面没有了srcipt等标签。

<?xml version="1.0"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml"version="1.0"initial="reset"><state id="reset"><transition event="watch.start"   target="running"/></state><state id="running"><transition event="watch.stop"    target="stopped"/></state><state id="stopped"><transition event="watch.start"   target="running"/><transition event="watch.reset"   target="reset"/></state></scxml>

2.3编写程序控制状态转移

需要操作的实体类（同时也是状态机类），用来约束秒表的行为：StopWatchStateMachine.java。这个类中的方法名字和上面的StopWatchEntity.java名字稍有不同，这个类里面的名字必须要和所对应的xml文件里面的状态名字相同。这是因为当状态发生转移的时候，进入某一个状态的时候，由框架自身根据反射机制去调用对应的方法。

package stopwatch;import org.apache.commons.scxml2.env.AbstractStateMachine;
import org.apache.commons.scxml2.model.ModelException;import java.util.Timer;
import java.util.TimerTask;public class StopWatchStateMachine extends AbstractStateMachine {public static final String EVENT_START = "watch.start";public static final String EVENT_STOP = "watch.stop";public static final String EVENT_RESET = "watch.reset";private int hr, min, sec, fract;private Timer timer;public StopWatchStateMachine() throws ModelException {super(StopWatchStateMachine.class.getResource("stopwatch3.xml"));}/*** 重置当前状态机，方法名和所在的状态名相同，又框架自己调用*/public void reset() {hr = min = sec = fract=0;timer=null;}/*** 运行秒表，方法名和所在的状态名相同，又框架自己调用*/public void running() {if (timer == null) {timer = new Timer(true);timer.scheduleAtFixedRate(new TimerTask() {@Overridepublic void run() {increment();}}, 100, 100);}}/*** 停止秒表，方法名和所在的状态名相同，又框架自己调用*/public void stopped() {timer.cancel();timer = null;}/*** 得到当前秒表的时间* @return*/public synchronized String getDisplay() {return String.format("%d:%02d:%02d,%d", hr, min, sec, fract);}//只是做一个演示，不使用这个方法public String getCurrentState() {return getEngine().getStatus().getStates().iterator().next().getId();}/*** 自增方法*/private synchronized void increment() {if (fract < 9) {fract++;} else {fract = 0;if (sec < 59) {sec++;} else {sec = 0;if (min < 59) {min++;} else {min = 0;hr++;}}}}
}

StopWatchDisplay.java 界面展现类

package stopwatch;import org.apache.commons.scxml2.model.ModelException;import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Timer;
import java.util.TimerTask;public class StopWatchDisplay extends JFrameimplements ActionListener {private static final long serialVersionUID = 1L;private JLabel displayLabel;private JButton startButton;private JButton stopButton;private JButton resetButton;private StopWatchStateMachine stopWatchStateMachine;public static void main(String[] args) throws Exception {new StopWatchDisplay();}public StopWatchDisplay() throws ModelException {super("SCXML StopWatch StateMachine");stopWatchStateMachine = new StopWatchStateMachine();initUI();}/*** 监听器需要执行的方法，自动调用* @param event 事件源*/public void actionPerformed(ActionEvent event) {//得到绑定在每个按钮上的命令String command = event.getActionCommand();//对各个命令进行判断，在执行相应的内容if ("START".equals(command)) {//生成watch.start事件，将转到running状态stopWatchStateMachine.fireEvent(StopWatchStateMachine.EVENT_START);//设置一些列按钮的可见性startButton.setEnabled(false);stopButton.setEnabled(true);resetButton.setEnabled(false);} else if ("STOP".equals(command)) {//生成watch.stop事件，将转到stoped状态stopWatchStateMachine.fireEvent(StopWatchStateMachine.EVENT_STOP);startButton.setEnabled(true);stopButton.setEnabled(false);resetButton.setEnabled(true);} else if ("RESET".equals(command)) {//生成watch.reset事件，将转到reset状态stopWatchStateMachine.fireEvent(StopWatchStateMachine.EVENT_RESET);startButton.setEnabled(true);stopButton.setEnabled(false);resetButton.setEnabled(false);}}/*** 初始化界面*/private void initUI() {JPanel mainPanel = new JPanel();mainPanel.setLayout(new BorderLayout());setContentPane(mainPanel);JPanel contentPanel = new JPanel();contentPanel.setLayout(new FlowLayout());displayLabel = new JLabel("0:00:00,000");displayLabel.setFont(new Font(Font.DIALOG, 100, 50));contentPanel.add(displayLabel, BorderLayout.CENTER);mainPanel.add(contentPanel, BorderLayout.CENTER);JPanel buttonPanel = new JPanel();buttonPanel.setLayout(new FlowLayout());startButton = createButton("START", "Start");buttonPanel.add(startButton);stopButton = createButton("STOP", "Stop");stopButton.setEnabled(false);buttonPanel.add(stopButton);resetButton = createButton("RESET", "Reset");resetButton.setEnabled(false);buttonPanel.add(resetButton);mainPanel.add(buttonPanel, BorderLayout.SOUTH);setLocation(250, 300);setSize(400,200);setResizable(true);setVisible(true);Timer displayTimer = new Timer();displayTimer.scheduleAtFixedRate(new TimerTask() {@Overridepublic void run() {displayLabel.setText(stopWatchStateMachine.getDisplay());}}, 100, 100);setDefaultCloseOperation(EXIT_ON_CLOSE);}/*** 创建一个按钮* @param command 按钮的命令* @param text 按钮上的文本* @return 返回一个新建的按钮*/private JButton createButton(final String command, final String text) {JButton button = new JButton(text);button.setActionCommand(command);button.addActionListener(this);return button;}}

2.4 程序结果分析

程序界面类中的定时器一直在访问 StopWatctStateMachine的getDisplay方法，来得到秒表的值。我们通过Start,Stop,Reset来控制秒表的状态，在进入某一个状态机的时候，由框架自动调用对应状态名相同的的函数，来改变秒表的值。当秒表一直处于某一个状态的时候，我们又通过点击按钮来改变秒表的状态。

源代码AbstractStateMachine.java中对应的调用语句如下

         /*** {@inheritDoc}*/public void onEntry(final EnterableState entered) {invoke(entered.getId());}/*** Invoke the no argument method with the following name.** @param methodName The method to invoke.* @return Whether the invoke was successful.*/public boolean invoke(final String methodName) {Class<?> clas = this.getClass();try {Method method = clas.getDeclaredMethod(methodName, SIGNATURE);method.invoke(this, PARAMETERS);} catch (SecurityException se) {logError(se);return false;} catch (NoSuchMethodException nsme) {logError(nsme);return false;} catch (IllegalArgumentException iae) {logError(iae);return false;} catch (IllegalAccessException iae) {logError(iae);return false;} catch (InvocationTargetException ite) {logError(ite);return false;}return true;}

3 两种方式的总结

其实第二种方式是官网给出的例子里面的，同时也是更贴近状态机对象的思想。但是也有如下缺点（也许）
1、 stopWatchStateMachine.fireEvent(StopWatchStateMachine.EVENT_START);只有这一个触发事件的函数，不能传递数据。而第一种方式里面的executor.triggerEvent(new TriggerEvent("watch.start", TriggerEvent.SIGNAL_EVENT),数据);可以通过触发时间传递数据进入状态机里面。