mycanvas.java

Java程序设计清华出版课件源码答案共十四章

import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class MyCanvas
	implements KeyListener,MouseListener{
	Canvas c;
	String s = "";
	TextField t;

public static void main(String args[]) {
	Frame f = new Frame("Canvas");
	MyCanvas mc = new MyCanvas();
	mc.c = new Canvas();
	mc.t = new TextField();
	f.add("South",mc.t);
	f.add("Center",mc.c);
	f.setSize(300,150);
	mc.c.addMouseListener(mc);
	mc.c.addKeyListener(mc);
	f.setVisible(true);
}

// 实现KeyListener接口中的方法
public void keyTyped(KeyEvent ev) {
	t.setText("keyTyped");
	s += ev.getKeyChar();

	// 将用户键入的字符写到画布上
	c.getGraphics().drawString(s,0,20);
}

public void keyPressed(KeyEvent ev) {}

public void keyReleased(KeyEvent ev) {
	t.setText("keyReleased");
}

//  实现MouseListener接口中的方法
public void mouseClicked (MouseEvent ev) {
	t.setText("mouseClicked");
	// 强制画布获取输入焦点
	c.requestFocus();
}

public void mousePressed(MouseEvent ev) {
	t.setText("mousePressed");
}

public void mouseReleased(MouseEvent ev) {
	t.setText("mouseReleased");
}

public void mouseEntered(MouseEvent ev) {
	t.setText("mouseEntered");
}
public void mouseExited(MouseEvent ev){
 	t.setText("mouseExited");
}
}