Java学习笔记线程实例：一个钟表的实现

2008-02-23 09:33:34来源：互联网阅读 ()

最近在学习Java线程，照着书上例子写的钟表图形程序，对线程有一定的理解，但是发觉对图形编程的掌握不够很多函数还不能掌握~~

以下是钟表例子的代码

package hello;
import java.awt.*;
import java.Applet.*;
import java.awt.event.*;
import java.util.*;
import java.awt.geom.*;

public class T extends Applet implements Runnable{
Thread tHour = null,tMinute = null,tSecond = null;//表示时针，分针和秒针的线程
int hour_a,hour_b,minute_a,minute_b,second_a,second_b;//表示时针，分针，秒针端点的整型变量
int hour = 0,minute = 0,second = 0;//获取当前时间的整型变量

//绘制时针，分针和秒针的Graphics对象
Graphics g_second = null,g_minute = null,g_hour =null;
//存放表盘刻度的数组，供指针走动时使用
double point_x[] = new double[61],point_y[] = new double[61];
//存放表盘刻度的数组，供绘制表盘使用
double scaled_x[] = new double[61],scaled_y[] = new double[61];
//判断小程序是否重新开始的变量
int start_count = 0;

public void init(){
g_hour = this.getGraphics();
g_hour.setColor(Color.CYAN);
g_second = this.getGraphics();
g_second.setColor(Color.RED);
g_minute = this.getGraphics();
g_minute.setColor(Color.blue);
g_second.translate(200,200);//进行坐标系统变换，将新坐标系原点设在（200，200）处
g_minute.translate(200,200);
g_hour.translate(200,200);
point_x[0] = 0; point_y[0] = -120;//各个时针12点处的位置坐标（按新坐标系的坐标）
scaled_x[0] = 0;scaled_y[0] = -140;//12点处的刻度位置坐标（按新坐标系的坐标）
double jiaodu = 6*Math.PI/180;
//表盘分割成60分，将分割点的坐标存放在数组中
for(int i = 0; i < 60; i ){
point_x[i 1] = point_x[i]*Math.cos(jiaodu)-Math.sin(jiaodu)*point_y[i];
point_y[i 1] = point_y[i]*Math.cos(jiaodu) point_x[i]*Math.sin(jiaodu);
}

point_x[60] = 0; point_y[60] = -120;

for(int i = 0; i < 60; i ){
scaled_x[i 1] = scaled_x[i]*Math.cos(jiaodu)-Math.sin(jiaodu)*scaled_y[i];
scaled_y[i 1] = scaled_y[i]*Math.cos(jiaodu) Math.sin(jiaodu)*scaled_x[i];
}
scaled_x[60]= 0;
scaled_y[60] = -140;
}
public void start(){
//每当小程序重新开始时，首先消灭线程，然后重新开始创建线程
if(start_count >= 1){
tSecond.interrupt();
tMinute.interrupt();
tHour.interrupt();
}
tSecond = new Thread(this);
tMinute = new Thread(this);
tHour = new Thread(this);
tSecond.start();
tMinute.start();
tHour.start();
start_count ;
if(start_count >= 2) start_count = 1;
}

public void stop()
{
tSecond.interrupt();
tMinute.interrupt();
tHour.interrupt();
}

public void paint(Graphics g){
this.start();
g.drawOval(50,50,300,300);//表盘的外圈
g.translate(200,200);
//绘制表盘的小刻度和大刻度
for(int i = 0 ; i < 60; i ){
if(i%5 == 0){
g.setColor(Color.BLACK);
g.fillOval((int) scaled_x[i],(int) scaled_y[i],10,10);
}
else
g.fillOval((int)scaled_x[i],(int)scaled_y[i],5,5);
}
}
public void run(){
//获取本地时间
Date date = new Date();
String s=date.toString();
hour=Integer.parseInt(s.substring(11,13));
minute = Integer.parseInt(s.substring(14,16));
second = Integer.parseInt(s.substring(17,19));
if(Thread.currentThread() == tSecond){
second_a =(int)point_x[second];
second_b = (int)point_x[second];
g_second.drawLine(0,0,second_a,second_b);//秒针的初始位置
g_second.drawString("秒",second_a,second_b);
int i = second;
while(true){
try{
tSecond.sleep(1000);
Color c = getBackground();
g_second.setColor(c);
g_second.drawLine(0,0,second_a,second_b);//用背景色清除前一秒时的秒针
g_second.drawString("秒",second_a,second_b);
//如果秒针与分针重合，恢复分针的显示
if((second_a == minute_a)&&(second_b == minute_b)){
g_minute.drawLine(0,0,minute_a,minute_b);
g_minute.drawString("分",minute_a,minute_b);
}
//如果秒针与时针重合，恢复时针的显示
if((second_a == hour_a)&&(second_b == hour_b)){
g_hour.drawLine(0,0,hour_a,hour_b);
g_hour.drawString("时",hour_a,hour_b);
}
}
catch(InterruptedException e){
Color c = getBackground();
g_second.setColor(c);
g_second.drawLine(0,0,second_a,second_b);//用背景色清除秒针
g_second.drawString("秒",second_a,second_b);
return;
}
//秒针向前走一个单位
second_a=(int)point_x[(i 1)`];
second_b = (int)point_y[(i 1)`]; //每一秒走6度（一个单位格）
g_second.setColor(Color.red);
g_second.drawLine(0,0,second_a,second_b);