(原创 by 徐剑生)《Java Swing之利用简单的多线程实现动态时钟》

package org.xt.util;

import java.awt.Point;

public class Circle {
    private Point centre;
    private int radius;

    public Circle(Point centre, int radius) {
        this.centre = centre;
        this.radius = radius;
    }

    public Point getCentre() {
        return centre;
    }

    public void setCentre(Point centre) {
        this.centre = centre;
    }

    public int getRadius() {
        return this.radius;
    }

    public void setRadius(int radius) {
        this.radius = radius;
    }
}

package org.xt.clock;

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.util.Calendar;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

@SuppressWarnings("serial")
public class Clock extends JComponent implements Runnable {
    private int radius;

    public Clock(int radius) {
        this.radius = radius;
    }

    public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D) g;

　　　　 //这两句话是去除线条锯齿的关键,至于原理笔者也不清楚,这两句是笔者从网络上找来的(就这两句不是自己写的,呵呵)
        g2d.setStroke(new BasicStroke(1.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

　　　　 //钟盘所在的矩形的左上角的坐标
        int clockPlateX = 0;
        int clockPlateY = 0;
        g2d.setColor(Color.GRAY);

　　　　 //画两个同心圆盘,作为时钟的边框
        g2d.drawOval(clockPlateX, clockPlateY, this.radius * 2, this.radius * 2);
        g2d.drawOval(clockPlateX + 5, clockPlateY + 5, this.radius * 2 - 10, this.radius * 2 - 10);

　　　　 //圆心坐标
        int centreX = this.radius;
        int centreY = centreX;

        g2d.setStroke(new BasicStroke(0.8f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));

　　　　 //这是钟盘中心的那个点
        g2d.fillOval(centreX - 3, centreY - 3, 6, 6);

        g2d.setStroke(new BasicStroke(2.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));

　　　　 //以下开始画大刻度,共有12个,表示有12个小时,基准是9时所指的刻度
        double degree = 0;
        double radian = Math.toRadians(degree);
        for (int i = 0; i < 12; ++i) {

　　　　　　　//计算刻度线相对位置位于左边的点
            int leftX = (int) ((double) centreX - (this.radius - 15) * Math.cos(radian));
            int leftY = (int) ((double) centreY - (this.radius - 15) * Math.sin(radian));

　　　　　　　//计算刻度线相对位置位于右边的点
            int rightX = (int) ((double) centreX - (this.radius - 25) * Math.cos(radian));
            int rightY = (int) ((double) centreY - (this.radius - 25) * Math.sin(radian));
　　　　　　
            g2d.drawLine(leftX, leftY, rightX, rightY);
            degree += 30;
　　　　　　　//将角度转换为弧度
            radian = Math.toRadians(degree);
        }

        g2d.setStroke(new BasicStroke(1.5f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
　　　　　
        //以下开始画小刻度,共有60-12=48个,基准是0时所指的刻度
        degree = 0;
        radian = Math.toRadians(degree);
        for (int i = 0; i < 60; ++i) {
　　　　     //此条件在于避免小刻度和大刻度重复
            if (i != 0 && degree % 30 != 0) {
                int leftX = (int) ((double) centreX - (this.radius - 15) * Math.cos(radian));
                int leftY = (int) ((double) centreY - (this.radius - 15) * Math.sin(radian));
                int rightX = (int) ((double) centreX - (this.radius - 17) * Math.cos(radian));
                int rightY = (int) ((double) centreY - (this.radius - 17) * Math.sin(radian));
                g2d.drawLine(leftX, leftY, rightX, rightY);
            }
　　　　　　  //每次增加6度
            degree += 360 / 60;
            //将角度转换为弧度
            radian = Math.toRadians(degree);
        }

　　　　 //获取当前的时,分,秒(Date类已经被淘汰,这里使用Calendar)
        Calendar cal = Calendar.getInstance();
        int second = cal.get(Calendar.SECOND);
        int minute = cal.get(Calendar.MINUTE);
        int hour = cal.get(Calendar.HOUR_OF_DAY);
        if (hour > 12) {
            hour = hour % 12;
        }

　　　　 //计算秒针当前距离开始位置的弧度,其余两句分别是分针和时针
        double secondProp = Math.toRadians(second * (360 / 60));
        double minuteProp = Math.toRadians(minute * (360 / 60));
        double hourProp = Math.toRadians((hour + minuteProp / (2 * Math.PI)) * (360 / 12));

        int leftX = (int) (centreX + (this.radius - 25) * Math.sin(secondProp));
        int leftY = (int) (centreY - (this.radius - 25) * Math.cos(secondProp));
        g2d.setStroke(new BasicStroke(1.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
        g.drawLine(leftX, leftY, centreX, centreY);

        leftX = (int) (centreX + (this.radius - 45) * Math.sin(minuteProp));
        leftY = (int) (centreY - (this.radius - 45) * Math.cos(minuteProp));
        g2d.setStroke(new BasicStroke(1.5f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
        g.drawLine(leftX, leftY, centreX, centreY);

        leftX = (int) (centreX + (this.radius - 70) * Math.sin(hourProp));
        leftY = (int) (centreY - (this.radius - 70) * Math.cos(hourProp));
        g2d.setStroke(new BasicStroke(2.5f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
        g.drawLine(leftX, leftY, centreX, centreY);
    }

    public void run() {
        while (true) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            this.repaint();
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        JPanel panel = new JPanel(new BorderLayout());
        frame.setContentPane(panel);
        Clock clock = new Clock(150);
        new Thread(clock).start();
        panel.add(clock, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(600, 400);
        frame.setVisible(true);
    }
}