14.11 스 레 드 와 Swing

import java.awt.*;
import java.util.*;

import javax.swing.*;

/**
 * This program demonstrates that a thread that runs in parallel with the event
 * dispatch thread can cause errors in Swing components.
 * @version 1.24 2015-06-21
 * @author Cay Horstmann
 */
public class SwingThreadTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new SwingThreadFrame();
         frame.setTitle("SwingThreadTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

/**
 * This frame has two buttons to fill a combo box from a separate thread. The
 * "Good" button uses the event queue, the "Bad" button modifies the combo box
 * directly.
 */
class SwingThreadFrame extends JFrame
{
   public SwingThreadFrame()
   {
      final JComboBox<Integer> combo = new JComboBox<>();
      combo.insertItemAt(Integer.MAX_VALUE, 0);
      combo.setPrototypeDisplayValue(combo.getItemAt(0));
      combo.setSelectedIndex(0);

      JPanel panel = new JPanel();

      JButton goodButton = new JButton("Good");
      goodButton.addActionListener(event ->
         new Thread(new GoodWorkerRunnable(combo)).start());
      panel.add(goodButton);
      JButton badButton = new JButton("Bad");
      badButton.addActionListener(event ->
         new Thread(new BadWorkerRunnable(combo)).start());
      panel.add(badButton);

      panel.add(combo);
      add(panel);
      pack();
   }
}

/**
 * This runnable modifies a combo box by randomly adding and removing numbers.
 * This can result in errors because the combo box methods are not synchronized
 * and both the worker thread and the event dispatch thread access the combo
 * box.
 */
class BadWorkerRunnable implements Runnable
{
   private JComboBox<Integer> combo;
   private Random generator;

   public BadWorkerRunnable(JComboBox aCombo)
   {
      combo = aCombo;
      generator = new Random();
   }

   public void run()
   {
      try
      {
         while (true)
         {
            int i = Math.abs(generator.nextInt());
            if (i % 2 == 0)
               combo.insertItemAt(i, 0);
            else if (combo.getItemCount() > 0)
               combo.removeItemAt(i % combo.getItemCount());
            Thread.sleep(1);
         }
      }
      catch (InterruptedException e)
      {
      }
   }
}

/**
 * This runnable modifies a combo box by randomly adding and removing numbers.
 * In order to ensure that the combo box is not corrupted, the editing
 * operations are forwarded to the event dispatch thread.
 */
class GoodWorkerRunnable implements Runnable
{
   private JComboBox<Integer> combo;
   private Random generator;

   public GoodWorkerRunnable(JComboBox aCombo)
   {
      combo = aCombo;
      generator = new Random();
   }

   public void run()
   {
      try
      {
         while (true)
         {
            EventQueue.invokeLater(() -> 
               {
                  int i = Math.abs(generator.nextInt());
                  if (i % 2 == 0)
                     combo.insertItemAt(i, 0);
                  else if (combo.getItemCount() > 0)
                     combo.removeItemAt(i % combo.getItemCount());
               });
            Thread.sleep(1);
         }
      }
      catch (InterruptedException e)
      {
      }
   }
}

import java.awt.*;
import java.io.*;
import java.util.*;
import java.util.List;
import java.util.concurrent.*;

import javax.swing.*;

/**
 * This program demonstrates a worker thread that runs a potentially time-consuming task.
 * @version 1.11 2015-06-21
 * @author Cay Horstmann
 */
public class SwingWorkerTest
{
   public static void main(String[] args) throws Exception
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new SwingWorkerFrame();
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

/**
 * This frame has a text area to show the contents of a text file, a menu to open a file and 
 * cancel the opening process, and a status line to show the file loading progress.
 */
class SwingWorkerFrame extends JFrame
{
   private JFileChooser chooser;
   private JTextArea textArea;
   private JLabel statusLine;
   private JMenuItem openItem;
   private JMenuItem cancelItem;
   private SwingWorker<StringBuilder, ProgressData> textReader;
   public static final int TEXT_ROWS = 20;
   public static final int TEXT_COLUMNS = 60;

   public SwingWorkerFrame()
   {
      chooser = new JFileChooser();
      chooser.setCurrentDirectory(new File("."));

      textArea = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
      add(new JScrollPane(textArea));

      statusLine = new JLabel(" ");
      add(statusLine, BorderLayout.SOUTH);

      JMenuBar menuBar = new JMenuBar();
      setJMenuBar(menuBar);

      JMenu menu = new JMenu("File");
      menuBar.add(menu);

      openItem = new JMenuItem("Open");
      menu.add(openItem);
      openItem.addActionListener(event -> {
            // show file chooser dialog
            int result = chooser.showOpenDialog(null);

            // if file selected, set it as icon of the label
            if (result == JFileChooser.APPROVE_OPTION)
            {
               textArea.setText("");
               openItem.setEnabled(false);
               textReader = new TextReader(chooser.getSelectedFile());
               textReader.execute();
               cancelItem.setEnabled(true);
            }
         });

      cancelItem = new JMenuItem("Cancel");
      menu.add(cancelItem);
      cancelItem.setEnabled(false);
      cancelItem.addActionListener(event -> textReader.cancel(true));
      pack();
   }

   private class ProgressData
   {
      public int number;
      public String line;
   }

   private class TextReader extends SwingWorker<StringBuilder, ProgressData>
   {
      private File file;
      private StringBuilder text = new StringBuilder();

      public TextReader(File file)
      {
         this.file = file;
      }

      // The following method executes in the worker thread; it doesn't touch Swing components.

      @Override
      public StringBuilder doInBackground() throws IOException, InterruptedException
      {
         int lineNumber = 0;
         try (Scanner in = new Scanner(new FileInputStream(file), "UTF-8"))
         {
            while (in.hasNextLine())         
            {
               String line = in.nextLine();
               lineNumber++;
               text.append(line).append("
");
               ProgressData data = new ProgressData();
               data.number = lineNumber;
               data.line = line;
               publish(data);
               Thread.sleep(1); // to test cancellation; no need to do this in your programs
            }
         }
         return text;
      }

      // The following methods execute in the event dispatch thread.

      @Override
      public void process(List data)
      {
         if (isCancelled()) return;
         StringBuilder b = new StringBuilder();
         statusLine.setText("" + data.get(data.size() - 1).number);
         for (ProgressData d : data) b.append(d.line).append("
");
         textArea.append(b.toString());
      }

      @Override
      public void done()
      {
         try
         {
            StringBuilder result = get();
            textArea.setText(result.toString());
            statusLine.setText("Done");
         }
         catch (InterruptedException ex)
         {
         }
         catch (CancellationException ex)
         {
            textArea.setText("");
            statusLine.setText("Cancelled");
         }
         catch (ExecutionException ex)
         {
            statusLine.setText("" + ex.getCause());
         }

         cancelItem.setEnabled(false);
         openItem.setEnabled(true);
      }
   };
}