paintrect.java

这是两个画矩形的小程序、程序主要通过获取鼠标的坐标

package PaintRect;

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.JFrame;
import javax.swing.JLabel;

public class PaintRect extends JFrame {

	private int x, y, a, b;

	public PaintRect() {
		super("DrawRect here");
		getContentPane().add(new JLabel("Drag the mouse to draw"),
				BorderLayout.SOUTH);

		addMouseMotionListener(

		new MouseMotionAdapter() {
			public void mouseDragged(MouseEvent event) {
				 a = event.getX();
				 b = event.getY();
				 repaint();
			}

		}

		);

		addMouseListener(new MouseAdapter() {
			public void mousePressed(MouseEvent event) {

				 x = event.getX();
				 y = event.getY();
			}

			public void mouseReleased(MouseEvent event) {

				a = event.getX();
				b = event.getY();

			}
		});

		setSize(300, 150);
		setVisible(true);

	}

	public void paint(Graphics g) {
		super.paint(g);

		 g.drawRect(x, y, Math.abs(a - x), Math.abs(b - y));

	}

	public static void main(String args[]) {
		PaintRect application = new PaintRect();
		application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
}