adspace.java

JSP核心技术源代码,和本站的JSP核心技术分析,可以合用

import java.util.*;
import java.applet.*;
import java.io.*;
import java.awt.*;
import java.net.*;

public class adSpace extends Applet implements Runnable {

  /**
   * Internal width and height
   **/

  int width,height;

  /**
   * Records whether the mouse is within the applet or not
   **/

  boolean mouseIn=false;

  /**
   * The thread that does the animation etc.
   **/

  Thread kicker=null;

  /**
   * Boolean variable to track whether the applet is running or not
   **/

  boolean running=false;

  /**
   * Index of currently displayed advert in Vector of advert objects
   **/

  int curIndex=0;

  /**
   * Boolean to record whether the animation is in progress or not
   **/

  boolean inScroll=false;

  /**
   * Handle to the current Advert object
   **/

  Advert curAdvert;

  /**
   * Handle to the next Advert object
   **/

  Advert newAdvert;

  /**
   * Length of time (milliseconds) to to display advert, before
   * animating to the next applet (default 4000)
   **/

  int pause=4000;

  /**
   * Pause between animation frames (default 100)
   **/

  int scrollPause=100;

  /**
   * The number of pixels between each frame in the scrolling animation
   **/

  int deltaY=2;

  /**
   * Number of frames in each scrolling animation. Defaults to -1 to
   * ensure initialisation
   **/

  int numFrames=-1;

  /**
   * Global audio clip played at the commencement of each animation
   **/

  AudioClip aniAudio = null;

  /**
   * Array of Advert objects. 1 Advert is created for each '{' '}' pair
   * found while parsing the configuration file
   **/

  Vector adverts = new Vector();

  /**
   * Total number of advers
   **/

  int numAds;

  /**
   * Loads configuration file and images/audio. Sets up dimensions,
   * animation style etc.
   **/

  public void init() {

    // Get the html parameters

    String adList = getParameter("adList");
    if (adList == null) {
      adList = "adlist.txt";
    }
    System.out.println("Got param: adList = " + adList);
   
    // retrieve the config file and parse it. This also creates
    // the array of Advert's
    parse_adlist(adList);
    System.out.println("Got " + adverts.size() + " adverts");

    String attr;
    attr=getParameter("pause");
    if (attr == null) {
      pause = 4000;
    } else {
      pause = Integer.parseInt(attr);
    }
    attr=getParameter("deltaY");
    if (attr == null) {
      deltaY = 2;
    } else {
      deltaY = Integer.parseInt(attr);
    }
    attr=getParameter("scrollPause");
    if (attr == null) {
      scrollPause = 40;
    } else {
      scrollPause = Integer.parseInt(attr);
    }
    attr=getParameter("numFrames");
    if (attr == null) {
      numFrames = -1;
    } else {
      numFrames = Integer.parseInt(attr);
    }
    attr=getParameter("aniAudio");
    if (attr == null) {
      aniAudio = null;
    } else {
      try {aniAudio = getAudioClip(new URL(getDocumentBase(),attr));} 
      catch (java.net.MalformedURLException e){};
    }

    numAds = adverts.size();

    curAdvert = (Advert)adverts.elementAt(0);
    newAdvert = curAdvert;
    curIndex=1;

    resize (curAdvert.image.getWidth(this), curAdvert.image.getHeight(this));
    width = size().width;
    height = size().height;

    if (numFrames != -1) {
      // ie. precedence goes to the user setting number of frames
      // in a scroll
      System.out.println("Overriding deltaY from " + deltaY + " to " +
			 (size().height / numFrames) + " ie. " + numFrames +
			 " frames");
      deltaY = size().height / numFrames;
    } else {
      numFrames = (int) Math.round((double)size().height / (double)deltaY);
    }

    try {
      im = createImage(size().width,size().height);
      out = im.getGraphics();
      System.out.println("GOT DOUBLE BUFFERING");
    } catch (Exception e) {
      // double-buffering not available
      out = null;
      System.out.println("NO DOUBLE BUFFERING");
    }
  }

  /**
   * Infinite loop which performs the animation etc.
   **/

  public void run () {
    while (kicker != null) {

      if (!inScroll) {
	if (curIndex >= numAds) {
	  curIndex = 0;
	}
	curAdvert = newAdvert;
	newAdvert = (Advert)adverts.elementAt(curIndex);

	try {Thread.sleep(pause);} catch (InterruptedException e){}

	curIndex++;
	inScroll = true;
      } else {
	try {Thread.sleep(scrollPause);} catch (InterruptedException e){}
	repaint();
	if (frameIdx >= numFrames) {
	  curAdvert = newAdvert;
	  inScroll = false;
	  frameIdx = 0;
	  printMessage();
	} else {
	  if ((frameIdx == 0) && (aniAudio != null)) {
	    aniAudio.play();
	    //	curAdvert.voice.play();
	  }
	  frameIdx++;
	}
      }
      Thread.currentThread().yield();
    }
  }

  /**
   * Creates the Thread
   **/

  public void start() {
    if (kicker == null) {
      kicker = new Thread(this);
      kicker.start();
      running = true;
    }
  }

  /**
   * Stop function is called when change page requested (by mouseDown)
   **/

  public void stop() {
    running = false;
    kicker.stop();
    kicker = null;
  }

  /**
   * Do the painting, if we have double buffering use it.
   *
   * @param g   Graphics object to draw to
   **/

  public void paint(Graphics g) {
    if (out != null) {
      // double-buffering available
      adSpacePaint(out);
      g.drawImage(im,0,0, this);
    } else {	
      adSpacePaint(g);
    }
  }

  /**
   * Calls paint to perform the painting
   *
   * @param g   Graphics object to draw to
   **/

  public void update(Graphics g) {
    paint(g);
  }

  /**
   * The off-screen double buffering Graphics
   **/

  Graphics out;

  /**
   * The image which will be linked to the off-screen off-screen Graphics
   **/

  Image im;

  /**
   * Index of current frame in animation scrolling
   **/

  int frameIdx=0;

  /**
   * This is the function which does all the painting work
   *
   * @param g   Graphics object to draw to
   **/

  private void adSpacePaint(Graphics g){

    // g.setColor(Color.black);
    // g.fillRect(0,0,size().width,size().height);
    
    if (newAdvert == null || curAdvert == null) {
      return;
    }

    Image scaled;
    g.clipRect(0, 0, size().width, size().height);
    if (inScroll == true) {
      /* This function is called at the browser's discretion, so must
       * check the value of frameIdx, make sure it isn't overrunning.
       */
      if ((newAdvert.image != null) && (frameIdx < numFrames) &&
	  (curAdvert.image != null) && (frameIdx < numFrames)) {
	newAdvert.paintFrame(g,0,0,frameIdx,0);
	curAdvert.paintFrame(g,0,frameIdx*deltaY+1,frameIdx,1);
      } else {
	g.drawImage(newAdvert.image,0,0, this);
      }
    } else {
      g.drawImage(curAdvert.image,0,0, this);
    }
  }
  
  /**
   * The mouse entering applet method
   **/

  public boolean mouseEnter(java.awt.Event evt, int x, int y) {
    mouseIn = true;
    printMessage();

    return true;
  }

  /**
   * The mouse leaving applet method
   **/

  public boolean mouseExit(java.awt.Event evt, int x, int y) {
    mouseIn = false;
    eraseMessage();

    return true;
  }

  /**
   * The mouse down applet method
   **/

  public boolean mouseDown(java.awt.Event evt, int x, int y) {
    stop();
    getAppletContext().showDocument(curAdvert.link);
    mouseIn = false;
    
    return true;
  }

  /**
   * The method to print the "Go to: ....." message at the foot of the page
   **/
  
  private void printMessage() {
    if (mouseIn) {
      if (curAdvert != null)
	{
	  if (curAdvert.link != null) {
	    getAppletContext().showStatus("Go to " 
					  + curAdvert.link.toExternalForm());
	  } else {
	    getAppletContext().showStatus("No URL to link to");
	  }
	}
    }
  }

  /**
   * Erase the message when the mouse leaves the applet area
   **/

  private void eraseMessage() {
    if (!mouseIn) {
      getAppletContext().showStatus("");
    }
  }

  /**
   * Parse the configuration file creating a new Advert and appending it
   * to the Vector of adverts for each '{' '}' pair found
   *
   * @param u   The string URL of the configuration file
   **/

  private void parse_adlist (String u) {
    // Create the url. Pass this URL in case relative url specified

    URL url = null;
    try {url = new URL (getDocumentBase(),u);}
    catch (java.net.MalformedURLException e) {
      System.out.println ("Can't get adlist " + u);
    }

    Advert advert=null;
    
    InputStream in = null;
    try {
      in = url.openStream();
    } catch (java.io.IOException e) {
      System.out.println("Didn't find URL: " + url.toExternalForm());
      return;
    }

    StreamTokenizer st = new StreamTokenizer(in);
    st.wordChars(0,255);
    st.eolIsSignificant(false);
    st.commentChar('#');
    st.whitespaceChars(' ',' ');
    st.whitespaceChars('\t','\t');
    st.whitespaceChars('\n','\n');
    st.whitespaceChars('\r','\r');
    st.ordinaryChar('{');
    st.ordinaryChar('}');

    int i=0;
	
    // while (st.nextToken() != StreamTokenizer.TT_EOF) {
    while (true) {
      try {
	if (st.nextToken() == StreamTokenizer.TT_EOF) {
	  break;
	}
      } catch (IOException e) {break;}

      if (st.ttype == '{') {
	// System.out.println("In a record");
	advert = new Advert (this);
      } else if ((st.ttype == StreamTokenizer.TT_WORD) && (i==0)) {
	System.out.println("Got ad URL: " + st.sval);
	advert.addImage(st.sval);
	i++;
      } else if ((st.ttype == StreamTokenizer.TT_WORD) && (i==1)) {
	System.out.println("Got Link: " + st.sval);
	advert.addLink(st.sval);
	i++;
      }else if ((st.ttype == StreamTokenizer.TT_WORD) && (i==2)) {
	System.out.println("Got Audio: " + st.sval);
	advert.addAudio(st.sval);
	i++;
      } else if (st.ttype == '}') {
	// System.out.println("Out of a record");
	if (advert != null) {
	  adverts.addElement(advert);
	  advert = null;
	}
	i=0;
      }
    }
  }
}


/**
 * Advert Class
 *
 * @author D. Nicol & C. Smeaton
 **/

class Advert {
        
  /**
   * The advertising image
   **/

  public Image image=null;

  /**
   * The URL this advert links to
   **/

  public URL link=null;

  /**
   * The containing applet object
   **/

  adSpace applet=null;

  /**
   * An audio clip to play (if present) when this advert is displayed
   **/

  public AudioClip voice=null;

  /** 
   * A static MediaTracker object to monitor down-load of images, 
   * and check for errors in image down-load
   **/

  static MediaTracker tracker;

  /**
   * Full construction of the object
   **/

  Advert (adSpace a, Image i, String s) {
    applet = a;

    try {link = new URL (applet.getDocumentBase(), s);}
    catch (java.net.MalformedURLException e) {};

    image = i;

    tracker = new MediaTracker(applet);
  }

  /**
   * Constructor with no members (other than Applet owner)
   **/

  Advert (adSpace a) {
    applet = a;
    image = null;
    link = null;

    tracker = new MediaTracker(applet);
  }

  /**
   * Add the image to the Advert. Uses media tracker to wait for loading
   **/

  public void addImage (Image i) {
    image = i;

    tracker.addImage(image,0);
    try {
      tracker.waitForID(0);
    } catch (InterruptedException e) {
      System.out.println("**Interrupted while waiting for image**");
    }
  }

  /**
   * Load the image, from the url.
   **/

  public void addImage (String s) {
    System.out.println("Imaghe is " + s);
    Image i = applet.getImage(applet.getDocumentBase(), s);
    addImage (i);
  }

  /**
   * Add the URL to link to
   **/

  public void addLink (String s) {
    try {link = new URL (applet.getDocumentBase(), s);}
    catch (java.net.MalformedURLException e){};
  }

  /**
   * Add an audio file to the Advert
   **/

  public void addAudio (String s) {
    try {voice = applet.getAudioClip(new URL(s));} 
    catch (java.net.MalformedURLException e){};
  }

  /**
   * Paint an animation frame. Frame determined from paramaters
   *
   * @param g     Graphics to draw to
   * @param x     x coordinate of area to draw to
   * @param y     y coordinate of area to draw to
   * @param idx   Index of frame to draw
   * @param type  0 = Shrinking (old advert); 1 = Growing (new advert)
   **/

  public boolean paintFrame (Graphics g, int x, int y, int idx, int type) {
    // Work out which frame we really want
    int frame=0;
    
    if (type == 0) {
      // Ok frame is idx
      frame = idx;
    } else if (type == 1) {
      // Right, frame is mirror image number
      int centre = applet.numFrames/2;
      int r = centre - idx - 1;
      frame = r + centre;	
    }
    
    if ((applet != null) && (image != null)) {
      int fh = (int)((double)frame * Math.abs(applet.deltaY) + 1.0f);
      fh = Math.min (fh, applet.size().height);
      
      try {
	g.drawImage (image, x, y, image.getWidth(applet), fh, applet);
      } catch (Exception e) {
	return false;
      }
    } else {
      return false;
    }
    
    return true;
  }

  /**
   * Simple check to see if everything went ok with creation of this
   * Advert object
   **/

  public boolean isSetup () {
    if (tracker.isErrorAny()) {
      System.out.println("ERROR IN LOADING IMAGES");
      return false;
    } else {
      return true;
    }
  }
}