Java的mouseExited事件觸發frame.setLocation（）被調用時

Question

我有一個沒有裝飾（沒有標題欄，關閉按鈕等）的JFrame，我可以使用setLocation（）和鼠標位置在屏幕上拖動。

遺憾的是，事件的mouseExited是在窗口的第一個舉動稱爲...

1. 移動鼠標到窗口的mouseEntered事件被觸發
2. 點擊鼠標的mousePressed和事件觸發。
3. 拖動鼠標和mouseDragged事件被觸發，並調用setLocation。
4. mouseExited事件被觸發，即使鼠標仍在窗口中！
5. 此時將鼠標移出窗口不會觸發mouseExited。
6. 移動鼠標並重新將重新回到步驟1

我該如何解決這個問題，除了在屏幕上只是手動測試鼠標的位置等？

編輯：下面的代碼

import java.awt.*; 
import javax.swing.*; 
import java.awt.Event; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseListener; 
import java.awt.event.MouseMotionListener; 

import javax.swing.JComponent; 
import javax.swing.JFrame; 

class DragNDropper implements MouseMotionListener, MouseListener 
{ 
    private int x, y; 
    private int dx, dy; 

    private boolean clicked; 

    private JFrame frame; 

    public DragNDropper(JFrame frame) 
    { 
    dx = dy = 0; 
    this.frame = frame; 
    } 

    public void mouseDragged(MouseEvent e) 
    { 
    x = e.getXOnScreen(); 
    y = e.getYOnScreen(); 

    frame.setLocation(x-dx, y-dy); 
    } 

    public void mouseMoved(MouseEvent e) 
    { 
    x = e.getXOnScreen(); 
    y = e.getYOnScreen(); 
    } 

    public void mouseClicked(MouseEvent e) 
    { 

    } 

    public void mousePressed(MouseEvent e) 
    { 
    clicked = true; 
    dx = e.getX(); 
    dy = e.getY(); 
    } 

    public void mouseReleased(MouseEvent e) 
    { 
    clicked = false; 
    } 

    public void mouseEntered(MouseEvent e) 
    { 
    System.out.println("Mouse entered"); 
    } 


    public void mouseExited(MouseEvent e) 
    { 
    System.out.println("Mouse exited"); 
    } 
} 


public class Program 
{ 
public static void main(String[] argv) 
{ 
JFrame jf = new JFrame(); 
DragNDropper dnd = new DragNDropper(jf); 

jf.setSize(new Dimension(512, 512)); 
jf.addMouseListener(dnd); 
jf.addMouseMotionListener(dnd); 

jf.show(); 
} 
} 

Answer 1

一切正常的精華版本，有了這個代碼。請停止使用frame.show()，從此知道此處用於顯示JFrame，請使用frame.setVisible(true)代替。請詳細解釋一下這個問題。請看看這個修改的代碼：

import java.awt.*; 
import java.awt.Event; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseListener; 
import java.awt.event.MouseMotionListener; 
import javax.swing.*; 

public class DragNDropper implements MouseMotionListener, MouseListener { 

    private int x, y; 
    private int dx, dy; 
    private boolean clicked;  
    private JFrame jf; 

    public static void main(String[] argv) { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       new DragNDropper().displayGUI(); 
      } 
     }); 
    } 

    private void displayGUI() { 
     dx = dy = 0; 
     jf = new JFrame(); 
     jf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
     jf.setUndecorated(true); 

     jf.setSize(new Dimension(512, 512)); 
     jf.addMouseListener(this); 
     jf.addMouseMotionListener(this); 

     jf.setVisible(true); 
    } 

    public void mouseDragged(MouseEvent e) { 
     x = e.getXOnScreen(); 
     y = e.getYOnScreen(); 
     jf.setLocation(x-dx, y-dy); 
    } 

    public void mouseMoved(MouseEvent e) { 
     x = e.getXOnScreen(); 
     y = e.getYOnScreen(); 
    } 

    public void mouseClicked(MouseEvent e) { 
    } 

    public void mousePressed(MouseEvent e) { 
     clicked = true; 
     dx = e.getX(); 
     dy = e.getY(); 
    } 

    public void mouseReleased(MouseEvent e) { 
     clicked = false; 
    } 

    public void mouseEntered(MouseEvent e) { 
     System.out.println("Mouse entered"); 
    } 

    public void mouseExited(MouseEvent e) { 
     System.out.println("Mouse exited"); 
    } 
}