这篇文章介绍了使用JFrame完成动态模拟时钟，在面板中绘制时钟并提取系统当前时刻，主方法中暂停线程1秒，刷新面板。

实现代码如下

import javax.swing.*;import java.awt.*;import java.util.*;import java.lang.Thread;import java.text.DecimalFormat; public class StillClock extends JPanel { /** * @param args */ private int hour; private int minute; private int second; //构造函数 public StillClock() { setCurrentTime(); } //返回小时 public int getHour() { return hour; } public int getMinute() { return minute; } public int getSecond() { return second; } //绘制时钟 protected void paintComponent(Graphics g) { super.paintComponent(g); //初始化 int clockRadius = (int)(Math.min(getWidth(), getHeight()) * 0.8 * 0.5); int xCenter = getWidth() / 2; int yCenter = getHeight() / 2; //画圆 g.setColor(Color.black); g.drawOval(xCenter - clockRadius, yCenter - clockRadius, 2 * clockRadius, 2 * clockRadius); g.drawString("12", xCenter - 5, yCenter - clockRadius + 15); g.drawString("9", xCenter - clockRadius + 3, yCenter + 5); g.drawString("3", xCenter + clockRadius - 10, yCenter + 3); g.drawString("6", xCenter - 3, yCenter + clockRadius - 3); //画秒针 int sLength = (int)(clockRadius * 0.8); int xSecond = (int)(xCenter + sLength * Math.sin(second * (2 * Math.PI / 60))); int ySecond = (int)(yCenter - sLength * Math.cos(second * (2 * Math.PI / 60))); g.setColor(Color.red); g.drawLine(xCenter, yCenter, xSecond, ySecond); //画分针 int mLenth = (int)(clockRadius * 0.65); int xMinute = (int)(xCenter + mLenth * Math.sin(minute * (2 * Math.PI / 60))); int yMinute = (int)(xCenter - mLenth * Math.cos(minute * (2 * Math.PI / 60))); g.setColor(Color.blue); g.drawLine(xCenter, yCenter, xMinute, yMinute); //画时针 int hLength = (int)(clockRadius * 0.5); int xHour = (int)(xCenter + hLength * Math.sin((hour % 12 + minute / 60.0) * (2 * Math.PI / 12))); int yHour = (int)(yCenter - hLength * Math.cos((hour % 12 + minute / 60.0) * (2 * Math.PI / 12))); g.setColor(Color.green); g.drawLine(xCenter, yCenter, xHour, yHour); //画数字时钟 g.setColor(Color.black); DecimalFormat s=new DecimalFormat("00"); g.drawString(s.format(getHour()) + ":" + s.format(getMinute()) + ":" + s.format(getSecond()), xCenter - 22, yCenter - clockRadius - 15); } public void setCurrentTime() { Calendar calendar = new GregorianCalendar(); this.hour = calendar.get(Calendar.HOUR_OF_DAY); this.minute = calendar.get(Calendar.MINUTE); this.second = calendar.get(Calendar.SECOND); } public static void main(String[] args) { // TODO Auto-generated method stub JFrame frame = new JFrame("DiaplayClock"); frame.setResizable(false); frame.setTitle("DiaplayClock"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(300,350); frame.setVisible(true); while(true) { StillClock clock = new StillClock(); frame.getContentPane().add(clock); clock.setVisible(true); frame.validate(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } clock.setVisible(false); frame.remove(clock); clock = null; frame.validate(); } }}

效果图：

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