How to customize messages in Java?

Sender: tomhzt (snil), email area: javatutorial

Question: Re: How to customize messages in Java?

Mailing station: BBS shuimu Tsinghua station (Mon Nov 8 19:18:46 2004), within the station

Here is an example from the book:

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)

{

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 ("Erased ");

Acceptbutton = new button ("OK ");



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 actionreceivmed (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 ("cocould 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 );

}



}

[Mentioned in the masterpiece of liyuexp (Yannan Fei :]

: How to customize a message in Java and accept the message for processing?

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