创建自定义工具包时，为什么 createFrame 在 OSX 上失败？

Question

我们正在尝试扩展UISpec4j 测试框架以在运行测试时显示用户界面。所以我们有一个自定义工具包，它围绕相关平台的本机工具包。我们设法让一切在 Windows XP 上运行良好，但是在 OSX 上测试我们的更改时，我们的 createFrame 扩展似乎表现得很奇怪：

 public FramePeer createFrame(Frame target) {
   FramePeer resultc = new UISpecFramePeer(target);
   //super.createFrame(target);

   return resultc;
 }

从本质上讲，我们想创建一个 UISpecFramePeer 作为拦截类...这样 UISpec4j 就可以询问 UI 中发生的事情。但是在我们的更改中，我们还希望显示 UI。所以我们尝试使用原生工具包创建一个框架并将其包装在 UISpecFramePeer 中（上面的代码中没有显示）。

当我们运行上述代码时，测试运行（如我们所料）但显然没有显示任何内容。但是，当我们包含 super.createFrame(target) 时。我们得到以下异常：

SEVERE: Application class org.openshapa.OpenSHAPA failed to launch
java.lang.ClassCastException: org.uispec4j.interception.toolkit.UISpecFramePeer
    at apple.awt.CWindow$8.convertJComponentToTarget(CWindow.java:236)
    at apple.awt.CWindow$8.convertJComponentToTarget(CWindow.java:233)
    at apple.awt.ClientPropertyApplicator.attachAndApplyClientProperties(ClientPropertyApplicator.java:24)
    at apple.awt.CWindow$1.propertyChange(CWindow.java:190)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:341)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:270)
    at java.awt.Component.firePropertyChange(Component.java:7277)
    at javax.swing.JComponent.addNotify(JComponent.java:4479)
    at javax.swing.JRootPane.addNotify(JRootPane.java:680)
    at java.awt.Container.addNotify(Container.java:2544)
    at java.awt.Window.addNotify(Window.java:467)
    at java.awt.Frame.addNotify(Frame.java:501)
    at java.awt.Window.pack(Window.java:485)
    at org.jdesktop.application.SingleFrameApplication.initRootPaneContainer(SingleFrameApplication.java:216)
    at org.jdesktop.application.SingleFrameApplication.show(SingleFrameApplication.java:463)
    at org.openshapa.OpenSHAPA.startup(OpenSHAPA.java:444)
    at org.jdesktop.application.Application$1.run(Application.java:171)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
    at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
Exception in thread "AWT-EventQueue-2" java.lang.Error: Application class org.openshapa.OpenSHAPA failed to launch
    at org.jdesktop.application.Application$1.run(Application.java:177)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
    at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
Caused by: java.lang.ClassCastException: org.uispec4j.interception.toolkit.UISpecFramePeer
    at apple.awt.CWindow$8.convertJComponentToTarget(CWindow.java:236)
    at apple.awt.CWindow$8.convertJComponentToTarget(CWindow.java:233)
    at apple.awt.ClientPropertyApplicator.attachAndApplyClientProperties(ClientPropertyApplicator.java:24)
    at apple.awt.CWindow$1.propertyChange(CWindow.java:190)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:341)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:270)
    at java.awt.Component.firePropertyChange(Component.java:7277)
    at javax.swing.JComponent.addNotify(JComponent.java:4479)
    at javax.swing.JRootPane.addNotify(JRootPane.java:680)
    at java.awt.Container.addNotify(Container.java:2544)
    at java.awt.Window.addNotify(Window.java:467)
    at java.awt.Frame.addNotify(Frame.java:501)
    at java.awt.Window.pack(Window.java:485)
    at org.jdesktop.application.SingleFrameApplication.initRootPaneContainer(SingleFrameApplication.java:216)
    at org.jdesktop.application.SingleFrameApplication.show(SingleFrameApplication.java:463)
    at org.openshapa.OpenSHAPA.startup(OpenSHAPA.java:444)
    at org.jdesktop.application.Application$1.run(Application.java:171)
    ... 7 more

为什么简单地使用本机工具包创建一个框架（但不返回它）会创建一个异常，而当 super.createFrame 被注释时它会正常运行？

Answer 1

我没有在 OSX 上工作过，但是在 Windows 上也会出现同样的问题，原因是这样的：

当您执行super.createFrame() 时，您实际上是在创建最终尝试显示的本机对等点，因此会调用 addNotify 方法。现在里面有很多方法直接将对等体转换为 WFramePeer（这是 Windows、OSX 的情况，它可能是 CWindowPeer 或其他），因此是 ClassCastException。在你的情况下，我的猜测是，CWindow 类试图投射你的UISpecFramePeer to WFramePeer(or CFramePeer or whatever)。只需通过反编译和检查来检查 CWindow 代码。请不要忘记发布您的发现。