clock.java

Java与模式 源代码

package com.javapatterns.chainofresp.clock;

import java.awt.*;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;

public class Clock extends java.applet.Applet implements Runnable
{
    private Thread clockThread = null;

    //Applet method
    public void init()
    {
        setBackground(Color.green);
    }

    //Applet method
    public void start()
    {
        if (clockThread == null)
        {
            clockThread = new Thread(this, "Clock");
            clockThread.start(); //thread starts running
        }
    }

    //A Thread method.
    public void run()
    {
        Thread myThread = Thread.currentThread();
        while (clockThread == myThread)
        {
            repaint(); //causes paint() to be called
            try
            {
                Thread.sleep(1000);
            }
            catch (InterruptedException e) { }
        }
    }

    //An applet method.
    public void paint(Graphics g)
    {
        Calendar cal = Calendar.getInstance();
        Date date = cal.getTime();
        DateFormat dateFormatter = DateFormat.getTimeInstance();
        g.drawString(dateFormatter.format(date), 5, 10);
    }

    // overrides Applet's stop method, not Thread's
    public void stop()
    {
        clockThread = null;
    }
}