stockapplet.java

帮助你系统进入JAVA的学习中来

/*
 * Copyright (c) 1996 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */

package examples.stock;

import java.applet.Applet;
import java.awt.*;
import java.net.URL;
import java.rmi.*;
import java.rmi.server.*;
import java.util.*;

/**
 * The StockApplet exports a remote object, and contacts the StockWatch
 * server to register interest in receiving stock updates.  The applet
 * displays the updates in a graph format.
 */
public class StockApplet extends Applet
	implements StockNotify, java.io.Serializable
{
    /** maximum number of updates displayed */
    static final int MAX_UPDATES = 34;
    /** maximum width of panel */
    private static final int width  = 500;
    /** maximum height of panel */
    private static final int height = 350;

    /** vector containing time of each update */
    private Vector time = new Vector(MAX_UPDATES);
    /** table mapping stock names to stock data */
    private Hashtable stockTable = new Hashtable();
    /** reference to StockWatch server */
    private StockWatch stockWatch = null;
    
    private String name[] = { "Sun", "HP", "Microsoft", "DEC","Novell",
			      "IBM","Apple","Netscape","Borland","SGI"};
    private Color color[]= { new Color(205,92,92),
			     Color.orange,
			     new Color(220,220,90),
			     new Color(85, 107, 47),
			     Color.blue,
			     new Color(160,32,240),
			     new Color(238, 130, 238),
			     Color.black,
			     new Color(205,120,92),
			     new Color(0,100,0) };
    
    /**
     * Notification of stock updates for a particular time.
     * @param date the time of the stock update
     * @param stocks an array containing the stocks for which the
     * object has registered interest.
     */
    public void update (Date date, Stock[] stock) 
    {
	System.out.println("StockApplet.update: " + date);
	// record date
	if (time.size() == MAX_UPDATES) { 
	    time.removeElementAt(0);
	}
	time.addElement(date);

	// record individual stock updates
	int numUpdates = time.size();
	for (int i=0; i<stock.length; i++) {
	    StockData data = (StockData)stockTable.get(stock[i].symbol);
	    if (data != null) {
		data.update(stock[i], numUpdates);
	    }
	}
	repaint();
    }

    /**
     * Initialize applet: export the applet as remote object that gets
     * notified of stock updates.
     */
    public void init() 
    {
	try {
	    // export the applet as a remote object
	    System.out.println("StockApplet.init: exporting remote object");
	    UnicastRemoteObject.exportObject(this);
	    
	    // lookup StockWatch server
	    URL base = getDocumentBase();
	    String serverName = "//" + base.getHost() + ":" +
		getParameter("registryPort") + "/example.stock.StockServer";
	    
	    System.out.println("StockApplet.init: looking up server");
	    stockWatch = (StockWatch)Naming.lookup(serverName);

	    // register interest in receiving stock updates
	    for (int i=0; i<name.length; i++) {
	    System.out.println("StockApplet.init: watch stock " + name[i]);
		stockWatch.watch(name[i], this);
		stockTable.put(name[i], new StockData(name[i], color[i]));
	    }
	    System.out.println("StockApplet.init: done registering stocks");
	    
	} catch (Exception e) {
	    // fatal error
	    System.out.println("got exception: " + e.getMessage());
	    e.printStackTrace();
	    return;
	}

        setLayout(null);

	// draw checkboxes
	Enumeration enum =  stockTable.elements();
	int i=0; 
	while (enum.hasMoreElements()) {
	    StockData data = (StockData)enum.nextElement();
            SensitiveCheckbox cb = new SensitiveCheckbox (data, this);
            data.cb = cb;
            add(cb);
            cb.setState(data.displayed);
            cb.reshape(10,i++*25+35,110,18);
        }
    }

    /**
     * Called when applet is destroyed; the applet cancels all
     * requests for stock updates.
     */
    public void destroy() 
    {
	// cancel request for stock updates
	if (stockWatch != null) {
	    try {
		stockWatch.cancelAll(this);
	    } catch (Exception e) {
		// eat exception
	    }
	}
    }

    /**
     * Called to repaint the panel.
     */
    public void paint(Graphics g) {

        // draw black boarder
        g.setColor(Color.black);
        g.drawRect(0,0,width-1,height-1);

        float miny = 0.0f;
        float maxy = 75.0f;

	// draw all stock data
	Enumeration enum = stockTable.elements();
	while (enum.hasMoreElements()) {
	    StockData data = (StockData)enum.nextElement();

            int size;
            Stock[] updates;
            synchronized (data.updates) {
                size = data.updates.size();
                updates = new Stock[size];
                data.updates.copyInto(updates);
            }
	    
            g.setColor(data.color);

            if (data.displayed) {
		// draw box around checkbox if mouse is over it
                if (data.cb != null && data.cb.haveMouse()) {
                    Point p = data.cb.location();
                    Dimension d = data.cb.size();

                    g.drawRect(p.x-1, p.y-1, d.width+4, d.height+4);
                    g.drawRect(p.x-2, p.y-2, d.width+4, d.height+4);
		    // point to graph for stock
                    if (size > 0)
                        g.drawLine(p.x+d.width+2,p.y+10,150,
                                   scale(updates[0].current));
                }
		// draw graph of updates for this stock
                int x = 150, inc = 10;
                for (int i = 0; i < size; i++) {
                    if (updates[i] != null) {
                        g.drawRect(x-1,scale(updates[i].current)-1,3,3);
                        if ((i < size - 1) && updates[i + 1] != null) {
                            int x2 = x + inc;
                            g.drawLine(x, scale(updates[i].current), x2,
                                       scale(updates[i + 1].current));
                        }
                    }
		    x += inc;
		}
	    }
        }
    }

    /**
     * Used to scale y-values.
     */
    int scale(float y) {
        return height - (int) (y*5+.5);
    }

    /**
     * Make sure that mouseHere is set properly (fix for windows
     * display problems).
     */
    void setMouseHere(boolean display) 
    {
	Enumeration enum = stockTable.elements();
	while (enum.hasMoreElements()) {
	    StockData data = (StockData)enum.nextElement();
	    data.cb.mouseHere = display;
	}
    }
}

/**
 * StockData contains stock updates and display information.
 */
class StockData {
    public String name;
    public Vector updates;
    public Color color;
    public boolean displayed;
    public SensitiveCheckbox cb;

    public StockData(String name, Color cl) {
        this.name = name;
        this.color = cl;
	this.updates = new Vector(StockApplet.MAX_UPDATES);
        displayed = true;
    }

    /**
     * Update stock.
     */
    void update(Stock stock, int numUpdates) 
    {
        synchronized (updates) {
            if (updates.size() == StockApplet.MAX_UPDATES) {
                updates.removeElementAt(0);
            }
            // If this stock has not received updates for previous timeslices,
            // fill them in with the current update value as well.
            if (updates.size() < numUpdates) {
                for (int i=updates.size(); i<numUpdates-1; i++) {
                    updates.addElement(stock);
                }
            }
            updates.addElement(stock);
        }
    }
}

/**
 * A mouse-sensitive checkbox that records whether the mouse is over
 * the checkbox.
 */
class SensitiveCheckbox extends Canvas {
    StockData data;
    boolean state = true;
    StockApplet panel;
    boolean mouseHere = false;

    public boolean haveMouse() {
        return mouseHere;
    }

    public SensitiveCheckbox(StockData data, StockApplet p) {
        this.data = data;
        panel = p;
    }

    public boolean mouseEnter(Event evt, int x, int y) {
        if (state) {
	    panel.setMouseHere(false); // for windows
            mouseHere = true;
            panel.repaint();
        }
        return false;
    }
    public boolean mouseExit(Event evt, int x, int y) {
        if (state) {
            mouseHere = false;
            panel.repaint();
        }
        return false;
    }

    public boolean mouseDown(Event evt, int x, int y) {
        if (state)
            state = false;
        else
            state = true;
        mouseHere=state;
        data.displayed = state;
        repaint();
        panel.repaint();
        return true;
    }

    public void paint(Graphics g) {
        g.setColor(Color.black);
        g.drawLine(4,4,14,4);
        g.drawLine(4,4,4,14);
        g.setColor(Color.gray);
        g.drawLine(5,14,14,14);
        g.drawLine(14,5,14,14);
        g.setColor(data.color);
        g.fillRect(5,5,8,8);
        g.setColor(data.color);
        g.drawString(data.name, 17,15);
        g.setColor(Color.black);
        if (state) {
            if (data.color == Color.black)
                g.setColor(Color.gray);
            if (data.color == Color.blue)
                g.setColor(Color.gray);
            g.drawLine(5,5,13,13);
            g.drawLine(5,6,12,13);
            g.drawLine(13,5,5,13);
            g.drawLine(13,6,6,13);
        }
    }

    public void setState(boolean s) {
        state = s;
        repaint();
    }
}