cammonitor.java

使用该APPLET可以让你在WEB里玩MUD

import java.awt.Graphics;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.Color;
import java.awt.Toolkit;
import java.awt.image.ImageObserver;

import java.net.URL;
import java.net.MalformedURLException;

import java.util.Date;

public class camMonitor extends Canvas implements Runnable {
  URL pic;
  int update;
  String id;
  Dimension size;
  Toolkit tk;
  Thread t;
  Image image, scaledImage;
  String time;

  /**
    * Initialize the cam monitor. 
    * @param url URL of the picture
    * @param update Update time in seconds.
    */
  public camMonitor(String id, String url, int update) {

    // initialize the URL
    try {
      pic = new URL(url);
    } catch(Exception e) {
      System.out.println("Unexpected Error: "+e);
      System.exit(1);;
    }
    this.id = id;
    this.update = update * 1000;

    size = new Dimension(100, 75);

    tk = this.getToolkit();

    t = new Thread(this);
    t.start();
  }

  boolean complete = false;

  /**
    * Download the picture every "update" seconds. The image will be
    * scaled to the size of the component. The aspect is restored when
    * the actual image size is known (2nd download).
    */
  public void run() {
    while(t != null) {
      // flush the image data (clear cache)
      if(image != null) image.flush();
      // download the image
      image = tk.getImage(pic);
      scaleImage();

      time = "";
      try {
	time = (new Date(pic.openConnection().getLastModified()))
	  .toString().substring(0, 16);
      } catch(Exception e) { 
	System.err.println("Could not determine modification time:");
	System.err.println(pic);
	time = "";
      }

      repaint();

      // sleep ...
      try {
	t.sleep(update);
      } catch(InterruptedException e) { 
	e.printStackTrace();
      }
    }
  }

  private void scaleImage() {
    if(image == null) return;

    Dimension size = new Dimension(getSize());
    if(size.width > size.height) {
	size.width = -1; 
	size.height -= 2;
    } else {
	size.width -= 2;
	size.height = -1;
    }
    scaledImage = image.getScaledInstance(size.width, size.height, 
					  Image.SCALE_SMOOTH);
  }

  /**
    * Paint the scaled image or write "No Image".
    * @param g Graphics context.
    */
  public void paint(Graphics g) {
    if(scaledImage != null ) {
      g.setColor(Color.white);
      g.draw3DRect(0, 0, size.width, size.height, true);
      g.drawImage(scaledImage, 1, 1, this);
      g.setColor(Color.black);
      g.setXORMode(Color.white);
      g.drawString(id, 3, getFontMetrics(getFont()).getHeight());
      g.drawString(time, 3, size.height - 3);
    } else {
      g.drawString(id, 3, getFontMetrics(getFont()).getHeight());
      g.drawString("No Image", 3, size.height - 3);
    }
  }

  public void setSize(Dimension d) {
    size = d;
    super.setSize(d);
    scaleImage();
  }

  public Dimension getPreferredSize() {
    return getSize();
  }

  /**
   * Get the current Image size.
   */
  public Dimension getSize() {
    return size;
  }
}