diningphilosophers.java

java程序设计

import javax.swing.*;
import java.net.URL;
import java.awt.*;
import java.io.*;
import java.util.*;
import javax.swing.SwingUtilities;

// for dealing with the start stop button
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

// for dealing with the delay slider
import javax.swing.event.ChangeListener;
import javax.swing.event.ChangeEvent;

import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;

public class DiningPhilosophers extends javax.swing.JApplet
           implements ActionListener, ChangeListener {

    // delays can go from 0 to 10,000 milliseconds, initial value is 500
    public int grabDelay = 500;
    private JButton stopStartButton = new JButton("start");
    private JSlider grabDelaySlider = new JSlider(JSlider.HORIZONTAL, 0, 100, 5);
    private JLabel label = new JLabel("  500 milliseconds");
    private JPanel philosopherArea;

    public Map<Dukes, ImageIcon> imgs;
    static final int NUMPHILS = 5;
    public Chopstick[] chopsticks = new Chopstick[NUMPHILS];
    private Philosopher[] philosophers = new Philosopher[NUMPHILS];
    String[] names = { "Arisduktle", "Dukrates", "Pythagoduke", 
											"Duko", "Dukimedes" };
    private int width = 0;
    private int height = 0;
    private double spacing;
    private static final double MARGIN = 10.0f;

		public void init() {
			imgs = new EnumMap<Dukes, ImageIcon>(Dukes.class);
			imgs.put(Dukes.HUNGRYDUKE, createAppletImageIcon("images/hungryduke.gif", "hungry duke"));
			imgs.put(Dukes.RIGHTSPOONDUKE, createAppletImageIcon("images/rightspoonduke.gif", "right spoon duke"));
			imgs.put(Dukes.BOTHSPOONSDUKE, createAppletImageIcon("images/bothspoonsduke.gif", "both spoon duke"));
			width = imgs.get(Dukes.HUNGRYDUKE).getIconWidth() + (int)(MARGIN*2.0);
			height = imgs.get(Dukes.HUNGRYDUKE).getIconHeight() + (int)(MARGIN*2.0);
			spacing = width + MARGIN;
			
			//Execute a job on the event-dispatching thread:
			//creating this applet's GUI.
			try {
				javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
					public void run() {
						createGUI();
					}
				});
			} catch (Exception e) {
				System.err.println("createGUI didn't successfully complete");
			}
		}
		
		private void createGUI() {
			
			GridBagLayout gridBag = new GridBagLayout();
			GridBagConstraints c = new GridBagConstraints();
			
			JPanel contentPane = new JPanel();
			contentPane.setLayout(gridBag);
			
			philosopherArea = new JPanel(null);
			philosopherArea.setBackground(Color.white);
			Dimension preferredSize = createPhilosophersAndChopsticks();
			philosopherArea.setBorder(BorderFactory.createCompoundBorder(
											BorderFactory.createLoweredBevelBorder(),
											BorderFactory.createEmptyBorder(5, 5, 5, 5)
			));
			philosopherArea.setPreferredSize(preferredSize);
			
			c.fill = GridBagConstraints.BOTH;
			c.weighty = 1.0;
			c.gridwidth = GridBagConstraints.REMAINDER; //end row
			gridBag.setConstraints(philosopherArea, c);
			contentPane.add(philosopherArea);
			
			c.fill = GridBagConstraints.HORIZONTAL;
			c.weightx = 1.0;
			c.weighty = 0.0;
			gridBag.setConstraints(stopStartButton, c);
			contentPane.add(stopStartButton);
			
			c.gridwidth = GridBagConstraints.RELATIVE; //don't end row
			c.weightx = 1.0;
			c.weighty = 0.0;
			gridBag.setConstraints(grabDelaySlider, c);
			contentPane.add(grabDelaySlider);
			
			c.weightx = 0.0;
			c.gridwidth = GridBagConstraints.REMAINDER; //end row
			gridBag.setConstraints(label, c);
			contentPane.add(label);
			contentPane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
			setContentPane(contentPane);
			
			stopStartButton.addActionListener(this);
			grabDelaySlider.addChangeListener(this);

    }

    public void actionPerformed(ActionEvent e) {
        if ("stop/reset".equals(stopStartButton.getText())) {
            stopPhilosophers();
            stopStartButton.setText("start");
        } else if ("start".equals(stopStartButton.getText())) {
            startPhilosophers();
            stopStartButton.setText("stop/reset");
        }
    }

    public void stateChanged(ChangeEvent e) {
        JSlider source = (JSlider)e.getSource();
        grabDelay = source.getValue()*100;
        label.setText(String.valueOf(grabDelay + " milliseconds"));
    }

    public void startPhilosophers() {
        for (int i = 0; i < NUMPHILS; i++)
            philosophers[i].philThread.start();
    }

    public void stopPhilosophers() {
        for (int i = 0; i < NUMPHILS; i++)
            philosophers[i].philThread.interrupt();
    }

    public Dimension createPhilosophersAndChopsticks() {
        double x, y;
        double radius = 80.0;
        double centerAdj = 85.0;
        double radians;

        Dimension preferredSize = new Dimension(0, 0);

        for (int i = 0; i < NUMPHILS; i++)
            chopsticks[i] = new Chopstick();

        for (int i = 0; i < NUMPHILS; i++) {
            radians = i*(2.0 * Math.PI /(double)NUMPHILS);
            x = Math.sin(radians) * radius + centerAdj; 
            y = Math.cos(radians) * radius + centerAdj; 
            philosophers[i] = new Philosopher(this, i);
            philosophers[i].setBounds((int)x, (int)y, width, height);
            philosopherArea.add(philosophers[i]);
            if ((int)x > preferredSize.width)
							preferredSize.width = (int)x;
            if ((int)y > preferredSize.height)
							preferredSize.height = (int)y;
        }

        preferredSize.width += width;
        preferredSize.height += height;
        return preferredSize;
    }

      protected static ImageIcon createAppletImageIcon(String path,
                                              String description) {
        int MAX_IMAGE_SIZE = 75000; //Change this to the size of
                                    //your biggest image, in bytes.
        int count = 0;
        BufferedInputStream imgStream = new BufferedInputStream(
           DiningPhilosophers.class.getResourceAsStream(path));
        if (imgStream != null) {
            byte buf[] = new byte[MAX_IMAGE_SIZE];
            try {
                count = imgStream.read(buf);
            } catch (IOException ieo) {
                System.err.println("Couldn't read stream from file: " + path);
            }

            try {
                imgStream.close();
            } catch (IOException ieo) {
                 System.err.println("Can't close file " + path);
            }

            if (count <= 0) {
                System.err.println("Empty file: " + path);
                return null;
            }
            return new ImageIcon(Toolkit.getDefaultToolkit().createImage(buf),
                                 description);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }
}