12.8 GUI程序的问题定位

1 Debug提示

import java.awt.*;

import javax.swing.*;

/**
 * @version 1.14 2015-08-20
 * @author Cay Horstmann
 */
public class EventTracerTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() ->
            {
               JFrame frame = new EventTracerFrame();
               frame.setTitle("EventTracerTest");      
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
            });
   }
}

class EventTracerFrame extends JFrame
{
   public EventTracerFrame()
   {
      // add a slider and a button
      add(new JSlider(), BorderLayout.NORTH);
      add(new JButton("Test"), BorderLayout.SOUTH);

      // trap all events of components inside the frame
      EventTracer tracer = new EventTracer();
      tracer.add(this);
      pack();
   }
}

import java.awt.*;
import java.beans.*;
import java.lang.reflect.*;

/**
 * @version 1.31 2004-05-10
 * @author Cay Horstmann
 */
public class EventTracer
{
   private InvocationHandler handler;

   public EventTracer()
   {
      // the handler for all event proxies
      handler = new InvocationHandler()
         {
            public Object invoke(Object proxy, Method method, Object[] args)
            {
               System.out.println(method + ":" + args[0]);
               return null;
            }
         };
   }

   /**
    * Adds event tracers for all events to which this component and its children can listen
    * @param c a component
    */
   public void add(Component c)
   {
      try
      {
         // get all events to which this component can listen
         BeanInfo info = Introspector.getBeanInfo(c.getClass());

         EventSetDescriptor[] eventSets = info.getEventSetDescriptors();
         for (EventSetDescriptor eventSet : eventSets)
            addListener(c, eventSet);
      }
      catch (IntrospectionException e)
      {
      }
      // ok not to add listeners if exception is thrown

      if (c instanceof Container)
      {
         // get all children and call add recursively
         for (Component comp : ((Container) c).getComponents())
            add(comp);
      }
   }

   /**
    * Add a listener to the given event set
    * @param c a component
    * @param eventSet a descriptor of a listener interface
    */
   public void addListener(Component c, EventSetDescriptor eventSet)
   {
      // make proxy object for this listener type and route all calls to the handler
      Object proxy = Proxy.newProxyInstance(null, new Class[] { eventSet.getListenerType() },
            handler);

      // add the proxy as a listener to the component
      Method addListenerMethod = eventSet.getAddListenerMethod();
      try
      {
         addListenerMethod.invoke(c, proxy);
      }
      catch (ReflectiveOperationException e)
      {
      }
      // ok not to add listener if exception is thrown
   }
}

---

2 让AWT Robot做事

Robot类可以模拟键盘和鼠标事件。

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;

/**
 * @version 1.05 2015-08-20
 * @author Cay Horstmann
 */
public class RobotTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() ->
            {
               // make frame with a button panel

               ButtonFrame frame = new ButtonFrame();
               frame.setTitle("ButtonTest");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
            });

      // attach a robot to the screen device

      GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
      GraphicsDevice screen = environment.getDefaultScreenDevice();

      try
      {
         final Robot robot = new Robot(screen);
         robot.waitForIdle();
         new Thread()
         {
            public void run() 
            {
               runTest(robot);                        
            };
         }.start();
      }
      catch (AWTException e)
      {
         e.printStackTrace();
      }     
   }

   /**
    * Runs a sample test procedure
    * @param robot the robot attached to the screen device
    */
   public static void runTest(Robot robot)
   {
      // simulate a space bar press
      robot.keyPress(' ');
      robot.keyRelease(' ');

      // simulate a tab key followed by a space
      robot.delay(2000);
      robot.keyPress(KeyEvent.VK_TAB);
      robot.keyRelease(KeyEvent.VK_TAB);
      robot.keyPress(' ');
      robot.keyRelease(' ');

      // simulate a mouse click over the rightmost button
      robot.delay(2000);
      robot.mouseMove(220, 40);
      robot.mousePress(InputEvent.BUTTON1_MASK);
      robot.mouseRelease(InputEvent.BUTTON1_MASK);

      // capture the screen and show the resulting image
      robot.delay(2000);
      BufferedImage image = robot.createScreenCapture(new Rectangle(0, 0, 400, 300));

      ImageFrame frame = new ImageFrame(image);      
      frame.setVisible(true);
   }
}

/**
 * A frame to display a captured image
 */
class ImageFrame extends JFrame
{
   private static final int DEFAULT_WIDTH = 450;
   private static final int DEFAULT_HEIGHT = 350;

   /**
    * @param image the image to display
    */
   public ImageFrame(Image image)
   {
      setTitle("Capture");
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      JLabel label = new JLabel(new ImageIcon(image));
      add(label);
   }
}

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * A frame with a button panel
 */
public class ButtonFrame extends JFrame
{
   private JPanel buttonPanel;
   private static final int DEFAULT_WIDTH = 300;
   private static final int DEFAULT_HEIGHT = 200;

   public ButtonFrame()
   {      
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      // create buttons
      JButton yellowButton = new JButton("Yellow");
      JButton blueButton = new JButton("Blue");
      JButton redButton = new JButton("Red");

      buttonPanel = new JPanel();

      // add buttons to panel
      buttonPanel.add(yellowButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(redButton);

      // add panel to frame
      add(buttonPanel);

      // create button actions
      ColorAction yellowAction = new ColorAction(Color.YELLOW);
      ColorAction blueAction = new ColorAction(Color.BLUE);
      ColorAction redAction = new ColorAction(Color.RED);

      // associate actions with buttons
      yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);
   }

   /**
    * An action listener that sets the panel's background color.
    */
   private class ColorAction implements ActionListener
   {
      private Color backgroundColor;

      public ColorAction(Color c)
      {
         backgroundColor = c;
      }

      public void actionPerformed(ActionEvent event)
      {
         buttonPanel.setBackground(backgroundColor);
      }
   }
}