哦.看到了
不过好复杂.看不太懂

没什么东西。。
就是算角度而已

就是一个时钟程序

import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.*;
import java.util.Calendar;
import java.util.GregorianCalender;

public class Clock extends JFrame implements ActionListener{
int x,y,x0,y0,r,h,olds_x,olds_y,oldm_x,oldm_y,oldh_x,oldh_y,ss,mm,hh,old_m,old_h,
ang;
final double RAD=Math.PI/180; //度数转化成弧度的比例

//构造函数创建一个窗体
public Clock(){
super("java 时钟");
setDefaultCloseOperation(3); 想问,这里是什么意思,为什么里面可以是个int值
Image image=getToolkit().getImage("clock gif");
setIconImage(image); 这里是什么意思呢
setSize(200,200);
setBackground(Color.BLACK);
setLocation(300,150);
setResizable(false);
show();
int delay=1000;
//创建一个监听事件
ActionListener drawClock=new ActionListener(){
public void actionPerformed(ActionEvent e){
repaint();
}
};
//创建一个时间计数器,每一秒触发一次
new Timer(delay,drawClock).start(); 这里呢,delay是什么意思,代表什么
}

//实现ActionListener接口必须实现的方法
public void actionPerformed(ActionEvent e){ }

//绘制图形
public void paint(Graphics g){
Insets insets=getInsets(); 这里又是什么意思
int L=insets.left/2,T=insets.top/2; 这里又是什么意思
h=getSize().height;
g.setColor(Color.white);
//画圆
g2D.setStrock(new BasicStrock(4.0f)); 这里又是什么意思
g.drawOval(L+40,T+40,h-80,h-80);
r=h/2-40;
x0=40+r-5+L;y0=40+r-5-T;
ang=60;
//绘制始终上的12个数字
for(int i=1;i<=12;i++){
x=(int)((r+10)*Math.cos(RAD*ang)+x0);
y=(int)((r+10)*Math.sin(RAD*ang)+y0);
g.drawString(""+i,x,h-y);
ang-=30;
}
//获得现在的时间
Calendar now=new GregorianCalendar();
int nowh=now.get(Calendar.HOUR_OF_DAY);
int nowm=now.get(Calendar.MINUTE);
int nows=now.get(Calendar.SECOND);
String st;
if(nowh<10) st="0"+nowh;else st=""+nowh;
if(nowm<10) st+=":0"+nowm; else st+=":"+nowm;
if(nows<10) st+=":0"+nows; else st+=":"+nows;
//在窗体上显示时间
g.setColor(Color.pink);
g.fillRect(L,T,50,28);
g.setColor(Color.blue);
g.drawString(st,L+2,T+26);
//计算时间与度数的关系
ss=90-nows*6;
mm=90-nowm*6;
hh=90-nowh*30-nowm/2;
x0=r+40+L;y0=r+40+T;
g2D.setStroke(new BasicStroke(1.2f));
//擦除秒针 下面擦除,绘制秒针,分针,时针看不明白.请高手解释下啊
if(olds_x>0){
g.setColor(getBackground());
g.drawLine(x0,y0,olds_x,olds_y);
}
else{
old_m=mm;old_h=hh;
}
//绘制秒针
x=(int)(r*0.9*Math.cos(RAD*ss))+x0;
y=(int)(r*0.9*Math.sin(RAD*ss))+y0-2*T;
g.setColor(Color.pink);
g.drawLine(x0,y0,x,h-y);
olds_x=x;olds_y=y;
g2D.setStroke(new BasicStroke(2.2f));
//擦除分针
if(old_m!=mm){
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
}
//绘制分真
x=(int)(r*0.7*Math.cos(RAD*ss))+x0;
y=(int)(r*0.7*Math.sin(RAD*ss))+y0-2*T;
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
oldm_x=x;oldm_y=y;
old_m=mm;
g2D.setStroke(new BasicStroke(3.4f));
//擦除时针
if(old_h!=hh){
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
}
//绘制时针
x=(int)(r*0.5*Math.cos(RAD*ss))+x0;
y=(int)(r*0.5*Math.sin(RAD*ss))+y0-2*T;
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
oldm_x=x;oldm_y=y;
old_h=hh;
}
public static void main(String[] args){
Clock clock=new Clock();
}

import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.*;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class Clock extends JFrame implements ActionListener{
int x,y,x0,y0,r,h,olds_x,olds_y,oldm_x,oldm_y,oldh_x,oldh_y,ss,mm,hh,old_m,old_h,
ang;
final double RAD=Math.PI/180; //度数转化成弧度的比例

//构造函数创建一个窗体
public Clock(){
super("java 时钟");
setDefaultCloseOperation(3); //等同于JFrame.EXIT_ON_CLOSE
Image image=getToolkit().getImage("clock gif");
setIconImage(image); //设置窗口左上角的图标
setSize(200,200);
setBackground(Color.BLACK);
setLocation(300,150);
setResizable(false);
show();
int delay=1000;
//创建一个监听事件
ActionListener drawClock=new ActionListener(){
public void actionPerformed(ActionEvent e){
repaint();
}
};
//创建一个时间计数器,每一秒触发一次
new Timer(delay,drawClock).start(); //它上面的注释很明白吧。。。1000毫秒触发一次。
}

//实现ActionListener接口必须实现的方法
public void actionPerformed(ActionEvent e){ }

//绘制图形
public void paint(Graphics g){
Insets insets=getInsets(); //Insets 对象是容器边界的表示形式。它指定容器必须在其各个边缘留出的空间。这个空间可以是边界、空白空间或标题。
int L=insets.left/2,T=insets.top/2; //此两处查api有明确说明
h=getSize().height;
g.setColor(Color.white);
//画圆
g2D.setStrock(new BasicStrock(4.0f)); //没用过。。查api
g.drawOval(L+40,T+40,h-80,h-80);
r=h/2-40;
x0=40+r-5+L;y0=40+r-5-T;
ang=60;
//绘制始终上的12个数字
for(int i=1;i<=12;i++){
x=(int)((r+10)*Math.cos(RAD*ang)+x0);
y=(int)((r+10)*Math.sin(RAD*ang)+y0);
g.drawString(""+i,x,h-y);
ang-=30;
}
//获得现在的时间
Calendar now=new GregorianCalendar();
int nowh=now.get(Calendar.HOUR_OF_DAY);
int nowm=now.get(Calendar.MINUTE);
int nows=now.get(Calendar.SECOND);
String st;
if(nowh<10) st="0"+nowh;else st=""+nowh;
if(nowm<10) st+=":0"+nowm; else st+=":"+nowm;
if(nows<10) st+=":0"+nows; else st+=":"+nows;
//在窗体上显示时间
g.setColor(Color.pink);
g.fillRect(L,T,50,28);
g.setColor(Color.blue);
g.drawString(st,L+2,T+26);
//计算时间与度数的关系
ss=90-nows*6;
mm=90-nowm*6;
hh=90-nowh*30-nowm/2;
x0=r+40+L;y0=r+40+T;
g2D.setStroke(new BasicStroke(1.2f));
//擦除秒针 擦出就是重新画。。取出背景色。。重新画一下而已。
if(olds_x>0){
g.setColor(getBackground());
g.drawLine(x0,y0,olds_x,olds_y);
}
else{
old_m=mm;old_h=hh;
}
//绘制秒针 绘制就设个于背景不同颜色。。再画出来。。
x=(int)(r*0.9*Math.cos(RAD*ss))+x0;
y=(int)(r*0.9*Math.sin(RAD*ss))+y0-2*T;
g.setColor(Color.pink);
g.drawLine(x0,y0,x,h-y);
olds_x=x;olds_y=y;
g2D.setStroke(new BasicStroke(2.2f));
//擦除分针
if(old_m!=mm){
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
}
//绘制分真
x=(int)(r*0.7*Math.cos(RAD*ss))+x0;
y=(int)(r*0.7*Math.sin(RAD*ss))+y0-2*T;
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
oldm_x=x;oldm_y=y;
old_m=mm;
g2D.setStroke(new BasicStroke(3.4f));
//擦除时针
if(old_h!=hh){
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
}
//绘制时针
x=(int)(r*0.5*Math.cos(RAD*ss))+x0;
y=(int)(r*0.5*Math.sin(RAD*ss))+y0-2*T;
g.setColor(getBackground());
g.drawLine(x0,y0,oldm_x,oldm_y);
oldm_x=x;oldm_y=y;
old_h=hh;
}
public static void main(String[] args){
Clock clock=new Clock();
}
}