好吧，在重新阅读您的问题后，似乎您不必担心拥有多个矩形:)
这是一次只能解决一个问题的解决方案（与您开始时的解决方案很接近）：
import java.awt.BorderLayout;import java.awt.Graphics;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import java.awt.event.MouseMotionListener;import javax.swing.Jframe;import javax.swing.JLabel;import javax.swing.SwingConstants;public class MouseTracker4July extends Jframe implements MouseListener, MouseMotionListener { private static final long serialVersionUID = 1L; private final JLabel mousePosition; int x1, x2, y1, y2; int x, y, w, h; private final JLabel recStart; private final JLabel recStop; private final JLabel cords; // set up GUI and register mouse event handlers boolean isNewRect = true; public MouseTracker4July() { super( "Rectangle Drawer" ); this.mousePosition = new JLabel(); this.mousePosition.setHorizontalAlignment( SwingConstants.CENTER ); getContentPane().add( this.mousePosition, BorderLayout.CENTER ); JLabel text1 = new JLabel(); text1.setText( "At the center the mouse pointer's coordinates will be displayed." ); getContentPane().add( text1, BorderLayout.SOUTH ); this.recStart = new JLabel(); getContentPane().add( this.recStart, BorderLayout.WEST ); this.recStop = new JLabel(); getContentPane().add( this.recStop, BorderLayout.EAST ); this.cords = new JLabel(); getContentPane().add( this.cords, BorderLayout.NORTH ); addMouseListener( this ); // listens for own mouse and addMouseMotionListener( this ); // mouse-motion events setSize( 800, 600 ); setVisible( true ); }// MouseListener event handlers // handle event when mouse released immediately after press public void mouseClicked( final MouseEvent event ) { this.mousePosition.setText( "Clicked at [" + event.getX() + ", " + event.getY() + "]" ); repaint(); }// handle event when mouse pressed public void mousePressed( final MouseEvent event ) { this.mousePosition.setText( "Pressed at [" + ( this.x1 = event.getX() ) + ", " + ( this.y1 = event.getY() ) + "]" ); this.recStart.setText( "Start: [" + this.x1 + ", " + this.y1 + "]" ); this.isNewRect = true; repaint(); }// handle event when mouse released after dragging public void mouseReleased( final MouseEvent event ) { this.mousePosition.setText( "Released at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" ); this.recStop.setText( "End: [" + this.x2 + ", " + this.y2 + "]" ); repaint(); }// handle event when mouse enters area public void mouseEntered( final MouseEvent event ) { this.mousePosition.setText( "Mouse entered at [" + event.getX() + ", " + event.getY() + "]" ); repaint(); }// handle event when mouse exits area public void mouseExited( final MouseEvent event ) { this.mousePosition.setText( "Mouse outside window" ); repaint(); }// MouseMotionListener event handlers // handle event when user drags mouse with button pressed public void mouseDragged( final MouseEvent event ) { this.mousePosition.setText( "Dragged at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" ); // call repaint which calls paint repaint(); this.isNewRect = false; repaint(); }// handle event when user moves mouse public void mouseMoved( final MouseEvent event ) { this.mousePosition.setText( "Moved at [" + event.getX() + ", " + event.getY() + "]" ); repaint(); } @Override public void paint( final Graphics g ) { super.paint( g ); // clear the frame surface g.drawString( "Start Rec Here", this.x1, this.y1 ); g.drawString( "End Rec Here", this.x2, this.y2 ); int width = this.x1 - this.x2; int height = this.y1 - this.y2; this.w = Math.abs( width ); this.h = Math.abs( height ); this.x = width < 0 ? this.x1 : this.x2; this.y = height < 0 ? this.y1 : this.y2; if ( !this.isNewRect ) { g.drawRect( this.x, this.y, this.w, this.h ); } this.cords.setText( "w = " + this.w + ", h = " + this.h ); } public static void main( final String args[] ) { MouseTracker4July application = new MouseTracker4July(); application.setDefaultCloseOperation( Jframe.EXIT_ON_CLOSE ); }} // end class MouseTracker
