progressbardemo.java~4~

Java 程序设计源码 只提供了部分

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

public class ProgressBarDemo extends JPanel
  implements ActionListener {
    public final static int ONE_SECOND = 1000;
    private JProgressBar progressBar;
    private Timer timer;
    private JButton startButton;
    private LongTask task;

    public ProgressBarDemo() {
      super(new BorderLayout());

      task = new LongTask();

      startButton = new JButton("start");

      startButton.addActionListener(this);

      progressBar = new JProgressBar(0, task.getLengthOfTask());
      progressBar.setValue(0);
      progressBar.setStringPainted(true);
      JPanel panel = new JPanel();
      panel.add(startButton);
      panel.add(progressBar);
      add(panel, BorderLayout.CENTER);

      timer = new Timer(ONE_SECOND,
                        new ActionListener() {
                          public void actionPerformed(ActionListener e) {
                            progressBar.setValue(task.getCurrent());

                            if(task.isDone()) {
                              ToolKit.getDefaultToolKit().beep();
                              timer.stop();
                              startButton.setEnabled();
                              setCursor(null);
                              progressBar.setValue(progressBar.getMinimum());
                            }
                          }
                        }
      );
    }

    public void actionPerformed(ActionEvent e) {
      startButton.setEnabled(false);
      setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
      task.go();
      timer.start();
    }

    public static void createAndShowGUI() {
      JFrame frame = new JFrame("ProgressBar Example");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      JComponent newContentPane = new ProgressBarDemo();
      newContentPane.setOpaque(true);
      frame.setContentPane(newContentPane);
      frame.pack();
      frame.setVisible(true);
    }

    public static void main(String[] args) {
      Javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
          createAndShowGUI();
        }
      });
    }
}

 class LongTask {
   private int lengthOfTask;
   private int current = 0;
   private boolean done = false;
   private boolean canceled = false;

   public LongTask() {
     lengthOfTask = 1000;
   }

   public void go() {
     final SwingWorker worker = new SwingWorker() {
       public Object construct() {
         current = 0;
         done = false;
         canceled = false;
         return new ActualTask();
       }
     };

     worker.start();
   }

   public int getLengthOfTask() {
     return lengthOfTask;
   }

   public int getCurrent() {
     return current;
   }

   public void stop() {
     canceled = true;
   }

   public boolean isDone() {
     return done;
   }

   class ActualTask {
     ActualTask() {
       while(!canceled && ! done) {
         try {
           Thread.sleep(1000);

           current += Math.random() * 100;

           if(current >= lengthOfTask) {
             done = true;
             current = lengthOfTask;
           }
         }
         catch(InterruptedException e) {
           System.out.println("ActualTask interrupted");
         }
       }
     }
   }
 }

abstract class SwingWorker {
  private Object value;

  private static class ThreadVar {
    private Thread thread;

    ThreadVar(Thread t) {
      thread = t;
    }

    synchronized Thread get() {
      return thread;
    }

    synchronized void clear() {
      thread = null;
    }
  }

  private ThreadVar threadVar;

  protected synchronized void setValue(Object x) {
    value = x;
  }

  private synchronized Object getValue() {
    return value;
  }

  public abstract Object construct();

  public void interrupt() {
    Thread t = threadVar.get();

    if( t != null) {
      t.interrupt();
    }

    threadVar.clear();
  }

  public Object get() {
    while(true) {
      Thread t = threadVar.get();

      if(t == null) {
        return getValue();
      }

      try {
        t.join();
      }
      catch(InterruptedException e) {
        Thread.currentThread().interrupt();
        return null;
      }
    }
  }

  public SwingWorker() {
    final Runnable doFinished = new Runnable() {
      public void run() {
        finished();
      }
    };

    Runnable doConstruct = new Runnable() {
      public void run() {
        try {
          setValue(construct());
        }
        /*
        catch(InterruptedException e) {

        }
*/
        finally {
          threadVar.clear();
        }

        SwingUtilities.invokeLater(doFinished);
      }
    };

    Thread t = new Thread(doConstruct);
    threadVar = new ThreadVar(t);
  }

  public void start() {
    Thread t = threadVar.get();
    if(t != null) {
      t.start();
    }
  }
}