moveboxinnercanvas.java

java编程开发技巧与实例的编译测试通过的所有例程

import java.awt.Graphics;
import java.awt.event.*;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.net.*;
import javax.swing.*;
import javax.swing.border.*;

public class MoveBoxInnerCanvas extends JApplet implements ActionListener
{
	private final	int BOX_WIDTH	=	200;
	private final	int BOX_HEIGHT	=	100;
	private final	int INC			=	4;
	private final	Color COLOR		=	Color.blue;
	private JButton		left		=	new JButton("Left");
	private JButton		right		=	new JButton("Right");
	private JButton		up			=	new JButton("Up");
	private JButton		down		=	new JButton("Down");
	private int x = 50,	y = 50;
	private class MoveBoxCanvas extends JPanel
	{
		public void paintComponent(Graphics g)
		{
			super.paintComponent(g);
			g.setColor(COLOR);
			g.fillRect(x, y, BOX_WIDTH, BOX_HEIGHT);
			g.setColor(Color.black);
			g.drawRect(0, 0, getSize().width - 1, getSize().height);
		}
	}
	private	MoveBoxCanvas drawing	=	new MoveBoxCanvas();
	public	void init()
	{
		JPanel buttons	=	new	JPanel(new FlowLayout());
		buttons.add(up);
		up.addActionListener(this);
		buttons.add(down);
		down.addActionListener(this);
		buttons.add(left);
		left.addActionListener(this);
		buttons.add(right);
		right.addActionListener(this);
		drawing.setBorder(new TitledBorder("The Box Playground"));
		buttons.setBorder(new TitledBorder("Move the Box"));
		try
		{
			URL base	=	getCodeBase();
			up.setIcon(new ImageIcon(new URL(base, "up.gif")));
			down.setIcon(new ImageIcon(new URL(base, "down.gif")));
			left.setIcon(new ImageIcon(new URL(base, "left.gif")));
			right.setIcon(new ImageIcon(new URL(base, "right.gif")));
			up.setToolTipText("Box up");
			down.setToolTipText("Box down");
			left.setToolTipText("Box left");
			right.setToolTipText("Box right");
		}
		catch	(MalformedURLException murle)
		{
			System.err.println("Error");
		}
		getContentPane().setLayout(new BorderLayout());
		getContentPane().add("South", buttons);
		getContentPane().add("Center", drawing);
		setSize(700, 300);
	}
	
	public void actionPerformed(ActionEvent ae)
	{
		if (ae.getSource() == up)
			y -= INC;
		else if (ae.getSource() == down)
			y += INC;
		else if (ae.getSource() == left)
			x -= INC;
		else if (ae.getSource() == right)
			x += INC;
		drawing.repaint();
	}
}