JInternalFrame動態顯示和隱藏標題欄

Question

開始時，我的JInternalFrame的標題欄被隱藏（((BasicInternalFrameUI) iw.getUI()).setNorthPane(null)）。只要鼠標進入框架邊界，我想再次顯示標題欄，直到邊框或標題欄本身將觸發mouseExit。

這是我第一次試驗：

public class InternalWindow extends JInternalFrame{ 
    public InternalWindow(){ 
     ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
     setResizable(true); 
     setVisible(true); 

     addMouseListener(new MouseAdapter() { 
      @Override 
      public void mouseEntered(MouseEvent e) { 
       ((BasicInternalFrameUI) iw.getUI()).setNorthPane(new BasicInternalFrameTitlePane(iw)); 
       ((BasicInternalFrameUI) iw.getUI()).getNorthPane().revalidate(); 
       ((BasicInternalFrameUI) iw.getUI()).getNorthPane().repaint(); 
       setFrameIcon(null); 
       revalidate(); 
       repaint(); 
       ((BasicInternalFrameUI) iw.getUI()).getNorthPane().addMouseListener(new MouseAdapter() { 
        @Override 
        public void mouseExited(MouseEvent e) { 
         ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
         revalidate(); 
         repaint(); 
        } 
       }); 
      } 
      @Override 
      public void mouseExited(MouseEvent e) { 
       ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
       revalidate(); 
       repaint(); 
      } 
     }); 
    } 
} 

但隨後的標題欄不正確繪製並且不對的互動反應。 (picture here)

所以我嘗試了另一種方式：

public class InternalWindow extends JInternalFrame{ 
    public InternalWindow(){ 
     ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
     setResizable(true); 
     setVisible(true); 

     addMouseListener(new MouseAdapter() { 
      @Override 
      public void mouseEntered(MouseEvent e) { 
       updateUI(); 
       setFrameIcon(null); 
       ((BasicInternalFrameUI) iw.getUI()).getNorthPane().addMouseListener(new MouseAdapter() { 
        @Override 
        public void mouseExited(MouseEvent e) { 
         ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
         revalidate(); 
         repaint(); 
        } 
       }); 
      } 
      @Override 
      public void mouseExited(MouseEvent e) { 
       ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
       revalidate(); 
       repaint(); 
      } 
     }); 
    } 
} 

這樣的標題欄繪製正確的，但因此AWT-EventQueue中拋出防止連接到邊界的mouseExited被稱爲異常：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException 
    at javax.swing.plaf.basic.BasicInternalFrameUI.updateFrameCursor(BasicInternalFrameUI.java:317) 
    at javax.swing.plaf.basic.BasicInternalFrameUI$BorderListener.mouseEntered(BasicInternalFrameUI.java:1086) 
    at java.awt.AWTEventMulticaster.mouseEntered(AWTEventMulticaster.java:300) 
    at java.awt.Component.processMouseEvent(Component.java:6544) 
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324) 
    at java.awt.Component.processEvent(Component.java:6300) 
    at java.awt.Container.processEvent(Container.java:2236) 
    at java.awt.Component.dispatchEventImpl(Component.java:4891) 
    at java.awt.Container.dispatchEventImpl(Container.java:2294) 
    at java.awt.Component.dispatchEvent(Component.java:4713) 
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888) 
    at java.awt.LightweightDispatcher.retargetMouseEnterExit(Container.java:4676) 
    at java.awt.LightweightDispatcher.trackMouseEnterExit(Container.java:4654) 
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4505) 
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466) 
    at java.awt.Container.dispatchEventImpl(Container.java:2280) 
    at java.awt.Window.dispatchEventImpl(Window.java:2750) 
    at java.awt.Component.dispatchEvent(Component.java:4713) 
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) 
    at java.awt.EventQueue.access$500(EventQueue.java:97) 
    at java.awt.EventQueue$3.run(EventQueue.java:709) 
    at java.awt.EventQueue$3.run(EventQueue.java:703) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) 
    at java.awt.EventQueue$4.run(EventQueue.java:731) 
    at java.awt.EventQueue$4.run(EventQueue.java:729) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) 
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) 

是不是隻有一種簡單的方法來動態地隱藏和顯示標題欄？

Answer 1

好吧，我剛剛發現了一些黑客入侵，只需爲mouseEntered和mouseExited的邊界註冊兩個單獨的MouseListeners，然後將鼠標移除並移出mouseEntered並在mouseExited的titlebar中讀取它。但我確定必須有一種更優雅的方式來達到這個目的...

MouseAdapter ma1 = new MouseAdapter() { 
     @Override 
     public void mouseExited(MouseEvent e) { 
      ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
      revalidate(); 
      repaint(); 
     } 
    }; 

    addMouseListener(new MouseAdapter() { 
     @Override 
     public void mouseEntered(MouseEvent e) { 
      updateUI(); 
      setFrameIcon(null); 
      ((BasicInternalFrameUI) iw.getUI()).getNorthPane().addMouseListener(new MouseAdapter() { 
       @Override 
       public void mouseExited(MouseEvent e) { 
        ((BasicInternalFrameUI) iw.getUI()).setNorthPane(null); 
        revalidate(); 
        repaint(); 
        addMouseListener(ma1); 
       } 
      }); 
      removeMouseListener(ma1); 
     } 
    });