java中如何自定义消息？

发信人: TOMHZT (snail), 信区: JavaTutorial

标  题: Re: java中如何自定义消息？

发信站: BBS 水木清华站 (Mon Nov  8 19:18:46 2004), 站内

这是从书上找的一个例子：

import java.util.EventObject;

import java.awt.Image;

class SignatureEvent extends EventObject

{

        protected Image signatureImage;

        

        public SignatureEvent(Object source, Image signature)

        {

                super(source);

                signatureImage = signature;

        }

        

        public Image getImage()

        {

                return signatureImage;

        }

}public interface SignatureEventListener

{

        public void userSigned(SignatureEvent signature);

        

}

import java.awt.Canvas;

import java.awt.*;

import java.awt.event.*;

import java.awt.image.*;

class SigningSurface extends Canvas

{

        protected int width, height;

        protected int x, y, lastX, lastY;

        protected Image offscreenImage = null;

        protected Graphics offscreenG;

        

        public SigningSurface()

        {

                enableEvents(AWTEvent.MOUSE_EVENT_MASK |

                             AWTEvent.MOUSE_MOTION_EVENT_MASK);

        }

        

        public void update(Graphics g)

        {

                paint(g);

        }

        

        public void paint(Graphics g)

        {

                if (offscreenImage == null)

                {

                        width  = getSize().width;

                        height = getSize().height;

                        offscreenImage = createImage(width, height);

                        if (offscreenImage == null)

                        {

                                System.out.println("Error: Couldn't create offScreen.");

                        }

                        offscreenG = offscreenImage.getGraphics();

                }

                g.drawImage(offscreenImage, 0, 0, this);

        }

        

        public void processMouseEvent(MouseEvent mouseEvent)

        {

                x = mouseEvent.getX();

                y = mouseEvent.getY();

                

                switch (mouseEvent.getID())

                {

                        case MouseEvent.MOUSE_PRESSED :

                        {

                                lastX = x;

                                lastY = y;

                                repaint();

                                break;

                        }

                        default:

                            break;

                }

        }

        

        protected void processMouseMotionEvent(MouseEvent mouseMotionEvent)

        {

                x = mouseMotionEvent.getX();

                y = mouseMotionEvent.getY();

                

                switch (mouseMotionEvent.getID())

                {

                        case MouseEvent.MOUSE_DRAGGED:

                        {

                                offscreenG.drawLine(x, y, lastX, lastY);

                                lastX = x;

                                lastY = y;

                                repaint();

                                break;

                        }

                        default:

                            break;

                }

        }

        

        public Image getImage()

        {

                return offscreenImage;

        }

        

        public void wipeSignature()

        {

                wipeImage(offscreenImage, Color.white, this);

                offscreenG.setColor(Color.black);

                repaint();

        }

        

        public static void wipeImage(Image im, Color col, ImageObserver observer)

        {

                Graphics g;

                int width, height;

                

                g = im.getGraphics();

                width  = im.getWidth(observer);

                height = im.getHeight(observer);

                g.setColor(col);

                g.fillRect(0, 0, width, height);

        }

        

} //endof class SigningSurface

import java.awt.*;

import java.awt.event.*;

import java.util.*;

public class SignMe extends Panel implements ActionListener

{

        protected SigningSurface scribble;

        protected Button eraseButton, acceptButton;

        protected SignatureEventListener sigListener = null;

        

        public SignMe()

        {

                Panel buttonsPanel, but1Panel, but2Panel;

                setLayout(new BorderLayout());

                scribble = new SigningSurface();

                buttonsPanel = new Panel();

                but1Panel = new Panel();

                but2Panel = new Panel();

                

                eraseButton = new Button("擦除");

                acceptButton = new Button("确定");

                

                but1Panel.add(eraseButton);

                but2Panel.add(acceptButton);

                buttonsPanel.add(but1Panel);

                buttonsPanel.add(but2Panel);

                add(scribble, "Center");

                add(buttonsPanel, "South");

                

                eraseButton.addActionListener(this);

                acceptButton.addActionListener(this);

        }

        

        public void actionPerformed(ActionEvent buttonClick)

        {

                if (buttonClick.getSource() == eraseButton)

                {

                        scribble.wipeSignature();

                }

                if (buttonClick.getSource() == acceptButton)

                {

                        System.out.println("user accepted signature!");

                        fireSignedEvent();

                }

        }

        

        public void addSignatureListener(SignatureEventListener listener)

                    throws java.util.TooManyListenersException

        {

                if (sigListener != null)

                {

                        throw new TooManyListenersException("SignMe already has an event listener");

                }

                sigListener = listener;

        }

        

        public void removeSignatureListener(SignatureEventListener listener)

        {

                if (sigListener == null)

                {

                        throw new IllegalArgumentException("Can't remove SignMe event");

                }

                

                if (sigListener != listener)

                {

                        throw new IllegalArgumentException("different from currently set!");

                }

                sigListener = null;

        }

        

        protected void fireSignedEvent()

        {

                SignatureEvent event;

                

                if (sigListener != null)

                {

                        event = new SignatureEvent(this, scribble.getImage());

                        sigListener.userSigned(event);

                }

        }

} //end of class SignMe

import java.awt.Frame;

import utilities.*;

import java.awt.*;

import java.awt.event.*;

import java.util.*;

class SignMeClient extends Frame implements SignatureEventListener

{

        protected SignMe sigWindow;

        

        public static void main(String[] args)

        {

                new SignMeClient();

        }

        

        public SignMeClient()

        {

                super("Sign Me Demo Window");

                sigWindow = new SignMe();

                

                try

                {

                        sigWindow.addSignatureListener(this);

                }

                catch (TooManyListenersException ex)

                {

                        System.out.println("Could not register " + ex);

                }

                

                add(sigWindow, "Center");

                setSize(new Dimension(350, 250));

                setVisible(true);

        }

        

        public void userSigned(SignatureEvent signed)

        {

                Frame receivedSignWindow;

                Graphics g;

                Image sigImage;

                int width, height;

                

                receivedSignWindow = new Frame("Received Signature");

                sigImage = signed.getImage();

                width = sigImage.getWidth(this);

                height = sigImage.getHeight(this);

                receivedSignWindow.setSize(new Dimension(width + 20, height + 20));

                receivedSignWindow.setVisible(true);

                MiscKit.delay(300);

                

                g = receivedSignWindow.getGraphics();

                int x = receivedSignWindow.getInsets().left;

                int y = receivedSignWindow.getInsets().top;

                g.drawImage(sigImage, x, y, receivedSignWindow);

                MiscKit.delay(1000);

                receivedSignWindow.setVisible(false);

        }

        

}

【 在 liyuexp (雁南飞) 的大作中提到: 】

: 如何在java中自定义消息 并且接受处理 请给个例子

--

※ 来源:·BBS 水木清华站 smth.org·[FROM: 202.112.78.*]