JavaSwing中随意拖动组件

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Color;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class DraggedTest extends JFrame {


private JPanel contentPane;


public static void main(String[] args) {


EventQueue.invokeLater(new Runnable() {



public void run() {




try {





DraggedTest frame = new DraggedTest();





frame.setVisible(true);




} catch (Exception e) {





e.printStackTrace();




}



}


});

}


public DraggedTest() {


setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


setSize(660, 500);


setLocationRelativeTo(null);


contentPane = new JPanel();


contentPane.setLayout(new BorderLayout());


add(contentPane);





JPanel panel = new JPanel();


contentPane.add(panel, BorderLayout.CENTER);


panel.setBorder(BorderFactory.createLineBorder(Color.orange, 2));


panel.setLayout(null);





JPanel panel_1 = new JPanel();


panel_1.setBackground(Color.GRAY);


panel_1.setBounds(82, 85, 130, 130);


panel.add(panel_1);





JPanel panel_2 = new JPanel();


panel_2.setBackground(Color.LIGHT_GRAY);


panel_2.setBounds(261, 85, 130, 130);


panel.add(panel_2);





JPanel panel_3 = new JPanel();


panel_3.setBackground(Color.MAGENTA);


panel_3.setBounds(450, 85, 130, 130);


panel.add(panel_3);





JPanel panel_4 = new JPanel();


panel_4.setBackground(Color.ORANGE);


panel_4.setBounds(261, 285, 130, 130);


panel.add(panel_4);





MyListener m = new MyListener();


panel_1.addMouseListener(m);


panel_1.addMouseMotionListener(m);





panel_2.addMouseListener(m);


panel_2.addMouseMotionListener(m);





panel_3.addMouseListener(m);


panel_3.addMouseMotionListener(m);





panel_4.addMouseListener(m);


panel_4.addMouseMotionListener(m);

}

// 写一个类继承鼠标监听器的适配器，这样就可以免掉不用的方法。

class MyListener extends MouseAdapter{


//这两组x和y为鼠标点下时在屏幕的位置和拖动时所在的位置


int newX,newY,oldX,oldY;


//这两个坐标为组件当前的坐标


int startX,startY;




@Override


public void mousePressed(MouseEvent e) {



//此为得到事件源组件



Component cp = (Component)e.getSource();



//当鼠标点下的时候记录组件当前的坐标与鼠标当前在屏幕的位置



startX = cp.getX();



startY = cp.getY();



oldX = e.getXOnScreen();



oldY = e.getYOnScreen();


}


@Override


public void mouseDragged(MouseEvent e) {



Component cp = (Component)e.getSource();



//拖动的时候记录新坐标



newX = e.getXOnScreen();



newY = e.getYOnScreen();



//设置bounds,将点下时记录的组件开始坐标与鼠标拖动的距离相加



cp.setBounds(startX+(newX - oldX), startY+(newY - oldY), cp.getWidth(), cp.getHeight());


}


}
}