5B2、如下图所示，利用Java的GUI和多线程编程技术，编写一个时钟显示程序。（30分）

http://s14/mw690/64ecfc2fgd08d6ef6619d&690例题 利用Java的GUI和多线程编程技术，编写一个时钟显示程序（第五届ITAT jav" TITLE="JAVA深入 例题 利用Java的GUI和多线程编程技术，编写一个时钟显示程序（第五届ITAT jav" />

 

public class ThreadClock extends JFrame implements Runnable{

     private volatileBufferedImage boardDrawing;//volatile是程度较轻的 synchronized

     private volatileBufferedImage boardDisplaying;

    

     publicThreadClock()

     {

         setTitle("ThreadClock");

         setSize(300, 300);

         setLocation(450,200);

         setDefaultCloseOperation(DISPOSE_ON_CLOSE);

         setVisible(true);

        

        boardDrawing = newBufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_RGB);

        boardDisplaying = newBufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_RGB);

     }

    

    public voidpaint(Graphics g) {

        g.drawImage(boardDisplaying, 0, 0, null);

    }

     @Override

     public void run() {

         //本来我这里的循环条件为true，不过测试运行了几次之后发现这个线程并没有被关闭

         //内存使用变成了3GB+，任务管理器中满是javaw.exe

         //后来用this.isShowing()来判断一下，终于可以顺利结束进程了

         while(this.isShowing())

         {

            Graphics g = boardDrawing.getGraphics();

            g.setColor(Color.WHITE);

            g.clearRect(0, 0, boardDrawing.getWidth(), boardDrawing.getHeight());//清除图形

            g.fillRect(0, 0, boardDrawing.getWidth(), boardDrawing.getHeight());//填充背景色为白色

           

            //画图

            //画出clock的表盘及数字

            g.setColor(Color.BLUE);

            g.drawOval(100, 100, 100, 100);

            g.drawString("12", 145, 115);

            g.drawString("6", 145, 195);

            g.drawString("9", 105, 155);

            g.drawString("3", 190, 155);

           

            //get Instance Time得到当前时间

            Calendar c=Calendar.getInstance();

            intweek=c.get(Calendar.DAY_OF_WEEK);

            intmonth=c.get(Calendar.MONTH);

            intday=c.get(Calendar.DATE);

            inthour=c.get(Calendar.HOUR_OF_DAY);

            intminute=c.get(Calendar.MINUTE);

            intsecond=c.get(Calendar.SECOND);

            int year=c.get(Calendar.YEAR);

           

            //画出时针分针秒针

            DrawHands(g, second/60.0, 40);

            DrawHands(g, minute/60.0, 32);

            DrawHands(g, (hour)/12.0, 25);

           

            String[] weekName={"星期日","星期一","星期二","星期三","星期四","星期五","星期六"};

            String[] monthName={"一月","二月","三月","四月","五月","六月","七月","八月","九月","十月","十一月","十二月"};

           

            //画出显示时间的字符串

            String timeString=String.format("%s %s - -:-:- %s", weekName[week],monthName[month],day,hour,minute,second,year);

            g.drawString(timeString, 75, 215);

            g.drawString("neolone", 240, 280);

           

            // 切换前景与背景工作区

            BufferedImage tmp = boardDisplaying;

            boardDisplaying = boardDrawing;

            boardDrawing = tmp;

            this.repaint();

           

            try {

                   Thread.sleep(500);

              } catch (Exception e) {

                   System.out.println(e);

              }

         }

     }

    

     //用g画出某根针（时分秒只是长度不同），percent表示从十二点到某指针现在的位置占整个圆周的百分比，length表示长度

     private voidDrawHands(Graphics g,Double percent,int length)

     {

         doubledegree=360*percent;

         int x=(int)(150+Math.cos(2*Math.PI*(90-degree)/360)*length);

         int y=(int)(150-Math.sin(2*Math.PI*(90-degree)/360)*length);

        

         g.drawLine(150, 150, x, y);

     }

    

     public static voidmain(String[] args) {

         // TODOAuto-generated method stub

         ThreadClock clock=newThreadClock();

         newThread(clock).start();

     }

}