mycanvas.java

矩阵乘法的计算程序

import java.awt.*;
import java.awt.event.*;
import java.util.*;
//MyCanvas是一个带有画布对象名的双重监听器
//画布组件相当于VB中的Picture控件,可以进行各种绘画操作
//画布组件可以监听各种鼠标与键盘事件
//系统为画布组件内置了一个Graphcis对象(通过getGraphics()方法获得)
//Graphcis对象可以完成各种图形绘制
public class MyCanvas implements KeyListener,MouseListener{
 Canvas c;
String s="";
	public static void main (String[] args)
	{
		Frame f=new Frame("Canvas");
		MyCanvas mc=new MyCanvas();
		mc.c=new Canvas();
	    f.add("Center",mc.c);
        f.setSize(150,150);
		mc.c.addMouseListener(mc);
		mc.c.addKeyListener(mc);
		f.setVisible(true);
	}
	public void mouseClicked(MouseEvent ev){
		System.out.println("MouseClicked");
		c.requestFocus();
		Graphics gp=c.getGraphics();
		gp.clearRect(0,0,150,150);
		int x=ev.getX();
		int y=ev.getY();
		gp.setColor(Color.green);
		//gp.drawRect(x,y,20,20);//第二组参数为第一组参数的相对值
		//gp.fillOval(x,y,30,20);
		int posx[]=new int[3];
		int posy[]=new int[3];
	    posx[0]=x;posx[1]=x-30;posx[2]=x+30;
		posy[0]=y;posy[1]=y+30;posy[2]=y+30;
		gp.drawPolygon(posx,posy,3);
	}
	
	public void keyTyped(KeyEvent ev){
		System.out.println("keyTyped");
		s+=ev.getKeyChar();
		c.getGraphics().drawString(s,0,20);
	}
	
	public void keyPressed(KeyEvent ev){
		System.out.println("KeyPressed");
	}	
	
	public void keyReleased(KeyEvent ev){
		System.out.println("KeyReleased");
	}
	
	public void mousePressed(MouseEvent ev){
		System.out.println("MousePressed");
	}
	
	public void mouseReleased(MouseEvent ev){
		System.out.println("MouseReleased");
	}
    public void mouseEntered(MouseEvent ev){
		System.out.println("MouseEntered");
	}
    public void mouseExited(MouseEvent ev){
		System.out.println("MouseExited");
	}
	
}