clock.java

这里一个用java写成的时钟的程序,从系统标准时间中读取目前准确时间,并用用户界面显示,有时针,分针,秒针的走动显示.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.Calendar;
import javax.swing.*;

public class Clock extends JPanel implements ActionListener 
{
	//创建时钟的外形
	protected static Ellipse2D face = new Ellipse2D.Float( 3, 3, 94, 94 );
    
	//创建时钟的标记
	protected static GeneralPath tick = new GeneralPath();

	static
	{
		tick.moveTo( 100, 100 );
		tick.moveTo( 49, 0 );
		tick.lineTo( 51, 0 );
		tick.lineTo( 49, 6 );
		tick.lineTo( 49, 0 );
	}

	//创建时针
	protected static GeneralPath hourHand = new GeneralPath();
	static
	{
		hourHand.moveTo( 50, 15 );
		hourHand.lineTo( 53, 50 );
		hourHand.lineTo( 50, 53 );
		hourHand.lineTo( 47, 50 );
		hourHand.lineTo( 50, 15 );
	}

	//创建分针
	protected static GeneralPath minuteHand = new GeneralPath();
	static
	{
		minuteHand.moveTo( 50, 2 );
		minuteHand.lineTo( 53, 50 );
		minuteHand.lineTo( 50, 58 );
		minuteHand.lineTo( 47, 50 );
		minuteHand.lineTo( 50, 2 );
	}

	//创建秒针
	protected static GeneralPath secondHand = new GeneralPath();
	static
	{
		secondHand.moveTo( 49, 5 );
		secondHand.lineTo( 51, 5 );
		secondHand.lineTo( 51, 62 );
		secondHand.lineTo( 49, 62 );
		secondHand.lineTo( 49, 5 );
	}

	//设置时钟的颜色
	protected static Color faceColor = new Color( 220, 220, 220 );
	protected static Color hourColor = Color.red.darker();
	protected static Color minuteColor = Color.blue.darker();
	protected static Color secondColor = new Color( 180, 180, 0 );
    protected static Color pinColor = Color.gray.brighter();

	//设置时钟的枢纽
	protected Ellipse2D pivot = new Ellipse2D.Float( 47, 47, 6, 6 );
    protected Ellipse2D centerPin = new Ellipse2D.Float( 49, 49, 2, 2 );
    
	//创建饶时钟枢纽转的变换
	protected AffineTransform hourTransform =
		AffineTransform.getRotateInstance( 0, 50, 50 );
	protected AffineTransform minuteTransform =
		AffineTransform.getRotateInstance( 0, 50, 50 );
	protected AffineTransform secondTransform =
		AffineTransform.getRotateInstance( 0, 50, 50 );

	//创建每秒触发一次的Timer
	protected Timer timer = new Timer( 1000, this );
	protected Calendar calendar = Calendar.getInstance();

	public Clock()
	{
		setPreferredSize( new Dimension( 100, 100 ) );
	}

	public void addNotify()
	{
		super.addNotify();
		timer.start();
	}

	public void removeNotify()
	{
		timer.stop();
		super.removeNotify();
	}

	public void actionPerformed( ActionEvent event )
	{
		//更新calendar的时间
		this.calendar.setTime( new java.util.Date() );
		int hours = this.calendar.get( Calendar.HOUR );
		int minutes = this.calendar.get( Calendar.MINUTE );
		int seconds = this.calendar.get( Calendar.SECOND );

		//设置变换， 使得时针、分针、秒针各自绕枢纽旋转一定的角度
		hourTransform.setToRotation( ( ( double ) hours ) * ( Math.PI / 6.0 ), 50, 50 );
		minuteTransform.setToRotation( ( ( double ) minutes ) * ( Math.PI / 30.0 ), 50, 50 );
		secondTransform.setToRotation( ( ( double ) seconds ) * ( Math.PI / 30.0 ), 50, 50 );

		repaint();
	}

	public void paint( Graphics g )
	{
		super.paint( g );

		//得到图形上下文和抗锯齿处理
		Graphics2D g2 = ( Graphics2D ) g;
		g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING,
			RenderingHints.VALUE_ANTIALIAS_ON );
		g2.setPaint( faceColor );
		g2.fill( face );
		g2.setPaint( Color.black );
		g2.draw( face );

		//产生钟面上12个滴答位置
		for( double p = 0.0; p < 12.0; p += 1.0 )
		{
			//利用变换画出同心的滴答的标线
			g2.fill( tick.createTransformedShape(
				AffineTransform.getRotateInstance( ( Math.PI / 6.0 ) * p, 50, 50 ) ) );
		}

		g2.setPaint( hourColor );
		g2.fill( hourHand.createTransformedShape( hourTransform ) );
		g2.setPaint( minuteColor );
		g2.fill( minuteHand.createTransformedShape( minuteTransform ) );
		g2.setPaint( secondColor );
		g2.fill( secondHand.createTransformedShape( secondTransform ) );
		g2.fill( pivot );
		g2.setPaint( pinColor );
		g2.fill( centerPin );
	}

	public static void main( String[] args )
	{
		JFrame frame = new JFrame();
		frame.setLocation( 700, 400 );
		frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
		frame.getContentPane().add( new Clock() );
		frame.pack();
		frame.show();
	}
}