应用名称：java动态模拟时钟

用到的知识：javaGUI，java 绘图

开发环境：win10+eclipse+jdk1.8

功能说明：通过java绘图画出一个虚拟的动态时钟

源代码：

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();      }  }}