clock.java

《java游戏设计》范例源代码及程序执行结果

// 程序：电子小时钟
// 范例文件：Clock.java

import java.awt.*;
import java.util.*;         //为了使用其中的GregorianCalendar类
import java.applet.*;

public class Clock extends Applet implements Runnable
{
   //=====资料成员==================================================
   int          hour,minute,second,ImageWidth,ImageHeight,X,Y,
                width,height;
   Image        digit[],Background,OffScreen;
   Thread       newThread;
   boolean      showSeparator;
   Graphics     drawOffScreen;
   MediaTracker MT;

   GregorianCalendar time;  //可用来获得时间与日期

   //=====函数成员==================================================
   public void init()
   {
      X      = 50;          //时间数字被绘制的起始位置
      Y      = 110;
      MT     = new MediaTracker(this); 
      digit  = new Image[11];
      width  = 210;         //重绘区域的大小
      height = 135;

      //使用MediaTracker追踪图像
      Background = getImage(getDocumentBase(),"Images/clock.jpg");
      MT.addImage(Background,0);

      for(int i=0;i<11;i++)
      {
         digit[i] = getImage(getDocumentBase(),"Images/" + i + ".jpg");
         MT.addImage(digit[i],0);
      }

      try
      {
         showStatus("图像加载中(Loading Images)...");
         MT.waitForAll();
      }
      catch(InterruptedException E){ }

      //获得图像的宽度与高度
      ImageWidth  = digit[0].getWidth(this);
      ImageHeight = digit[0].getHeight(this);

      //建立次画面
      OffScreen     = createImage(300,300);
      drawOffScreen = OffScreen.getGraphics();

      showSeparator = true; //显示时间分隔符
   }

   public void start()                   //start()函数  
   {
      newThread = new Thread(this);      //建立与启动新线程
      newThread.start();
   }

   public void stop()                    //stop()函数
   {
      newThread = null;                  //将线程设为null
   }

   public void paint(Graphics g)
   {
      //只清除此部分区域的图像
      drawOffScreen.clearRect(X,Y,width,height);
     
      //绘制背景图像
      drawOffScreen.drawImage(Background,0,0,this);

      if(hour < 10)     //绘制小时
      {
         drawOffScreen.drawImage(digit[0],X,Y,this);
         drawOffScreen.drawImage(digit[hour],X+ImageWidth,Y,this);
      }
      else
      {
         drawOffScreen.drawImage(digit[hour/10],X,Y,this);
         drawOffScreen.drawImage(digit[hour%10],X+ImageWidth,Y,this);
      }

      if(minute < 10)   //绘制分钟
      {
          
         drawOffScreen.drawImage(digit[0],X+ImageWidth*2+10,Y,this);
         drawOffScreen.drawImage(digit[minute],X+ImageWidth*3+10,Y,this);
      }
      else
      {
         drawOffScreen.drawImage(digit[minute/10],X+ImageWidth*2+10,Y,this);
         drawOffScreen.drawImage(digit[minute%10],X+ImageWidth*3+10,Y,this);
      }

      if(second < 10)   //绘制秒数
      {
         drawOffScreen.drawImage(digit[0],X+ImageWidth*4+15,
                                 Y+ImageHeight-30,15,30,this);
         drawOffScreen.drawImage(digit[second],X+ImageWidth*4+30,
                                 Y+ImageHeight-30,15,30,this);
      }
      else
      {
         drawOffScreen.drawImage(digit[second/10],X+ImageWidth*4+15,
                                 Y+ImageHeight-30,15,30,this);
         drawOffScreen.drawImage(digit[second%10],X+ImageWidth*4+30,
                                 Y+ImageHeight-30,15,30,this);
      }     

      if(showSeparator) //绘制时间分隔符(闪烁效果)
         drawOffScreen.drawImage(digit[10],X+ImageWidth*2,Y+10,this);

      //将次画面贴到主画面中
      g.drawImage(OffScreen,0,0,this);
   }

   public void update(Graphics g)        //update()函数
   {
      paint(g);                          //只单纯调用paint()函数
   }

   public void run()
   {  
      while(newThread != null)           //动画循环
      {  
         //time将包含目前系统的时间与日期 
         time   = new GregorianCalendar();

         //取出目前时间的小时、分钟和秒数
         hour   = time.get(Calendar.HOUR_OF_DAY);
         minute = time.get(Calendar.MINUTE);
         second = time.get(Calendar.SECOND);

         if(second % 2 == 0)             //控制时间分隔符的闪动
            showSeparator = true;
         else
            showSeparator = false;
 
         repaint(X,Y,width,height);      //重新绘制图像
          try
         {
            Thread.sleep(500);           //暂停程序执行500毫秒
         }
         catch(InterruptedException E){ }//没有进行例外处理
      }
   }
}