java怎么实现鼠标拖动画矩形

要实现鼠标拖动画矩形，可以使用Java的Swing库来完成。下面是一个简单的示例代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class DraggableRectangle extends JFrame {
    private int initialX, initialY;
    private int currentX, currentY;
    private Rectangle rectangle;

    public DraggableRectangle() {
        setTitle("Draggable Rectangle");
        setSize(400, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 创建矩形并设置初始位置和大小
        rectangle = new Rectangle(100, 100, 100, 100);

        // 添加鼠标事件监听器
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                // 记录鼠标按下时的初始位置
                initialX = e.getX();
                initialY = e.getY();
            }
        });

        addMouseMotionListener(new MouseAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                // 计算鼠标拖动后的位置
                currentX = e.getX();
                currentY = e.getY();

                // 计算矩形的偏移量
                int offsetX = currentX - initialX;
                int offsetY = currentY - initialY;

                // 更新矩形的位置
                rectangle.setLocation(rectangle.x + offsetX, rectangle.y + offsetY);

                // 重绘窗口
                repaint();

                // 更新初始位置
                initialX = currentX;
                initialY = currentY;
            }
        });
    }

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

        // 绘制矩形
        g.fillRect(rectangle.x, rectangle.y, rectangle.width, rectangle.height);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            DraggableRectangle draggableRectangle = new DraggableRectangle();
            draggableRectangle.setVisible(true);
        });
    }
}

运行以上代码，将会显示一个可拖动的矩形窗口。当鼠标按下并拖动时，矩形会跟随鼠标的移动而移动。