digitclock.java

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package digitclock;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.util.Date;

/**
 * <p>Title: 数字时钟</p>
 * <p>Description: 以图片方式显示时钟</p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: 北京师范大学计算机系</p>
 * @author 孙一林
 * @version 1.0
 */

public class DigitClock extends MultiThreadApplet {
  boolean isStandalone = false;

  Image[] digit_image = new Image[10];	// 数码（0－9）图像数组
  Image colon_image,					// 冒号图像
  frame_image;					// 边框图像
  int digit_height = 21;				// 数码（及冒号）高度
  int digit_width = 16;				// 数码宽度
  int colon_width = 9;				// 冒号宽度
  int offset = 4;						// 边框厚度
  int applet_width ,applet_height;	// 定义小出现宽、高变量
  int[] image_start_x = new int[8];	  // 数码或冒号的水平起始位置数组

  //Get a parameter value
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }

  //Construct the applet
  public DigitClock() {
  }
  //Initialize the applet
  public void init() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception {
    for (int i = 0; i < 10; i++){
      digit_image[i] = 					// 读取图像到数组缓冲区
      getImage( getCodeBase(), "lcdimages/lcd" + i + ".gif" );
    }
    colon_image = getImage( getCodeBase(), "lcdimages/colon.gif" );
    frame_image = getImage( getCodeBase(), "lcdimages/frame.gif" );
    applet_width = ( 2 * offset ) + ( 6 * digit_width ) + ( 2 * colon_width );
										// 计算显示宽度
    applet_height = ( 2 * offset ) + ( digit_height );
												// 计算显示高度
    image_start_x[0] = offset;			// 填充起始位置数组
    for (int i = 1; i < 8; i++){
      if ( (i == 3) || (i == 6) ){			// 计算冒号位置
        image_start_x[i] = image_start_x[i - 1] + colon_width;
      }
      else{								// 计算数码位置
        image_start_x[i] = image_start_x[i - 1] + digit_width;
      }
    }
  }

  public void paint( Graphics g ) {
    Date now = new Date();				// 获取当前日期和时间的对象
    int hour = now.getHours();			// 取小时数
    int minute = now.getMinutes();		// 取分钟数
    int second = now.getSeconds();		// 取秒钟数
    int	i = 0;							// 水平起始位置数组的索引
    g.drawImage(frame_image, 0, 0, this);
    g.drawImage( digit_image[hour / 10],image_start_x[i++],offset,this );
    g.drawImage( digit_image[hour % 10],image_start_x[i++],offset,this );
    g.drawImage( colon_image,image_start_x[i++],offset,this);// 显示冒号
    g.drawImage(digit_image[minute/10],image_start_x[i++],offset,this);
    g.drawImage(digit_image[minute%10],image_start_x[i++],offset,this);
    g.drawImage(colon_image,image_start_x[i++],offset,this);// 显示冒号
    g.drawImage(digit_image[second/10],image_start_x[i++],offset,this);
    g.drawImage(digit_image[second%10], image_start_x[i],offset,this );
  }										// 按时、分、秒位置显示图像

  public void run() {
    while ( thisThread != null ) {
      try{
        thisThread.sleep(1000);			// 1秒延时，每秒显示一次
    }
    catch (InterruptedException e){
    }
    repaint();
    }
  }

  //Get Applet information
  public String getAppletInfo() {
    return "Applet Information";
  }
  //Get parameter info
  public String[][] getParameterInfo() {
    return null;
  }
}