JavaFX应用程序和控制器类之间的FXML通信

我试图获取并销毁通过ProcessBuilder在我的FXML应用程序中创建的外部进程关闭，但它不工作。这是基于有用的建议Sergey Grinev gave me here。我试过运行/没有“// myController.setApp（this）;”和“// super.stop（）;”在子类顶部和底部（请参阅MyApp中的该行注释/），但没有组合起作用。JavaFX应用程序和控制器类之间的FXML通信

这可能与FXML或JavaFX无关，但我想这是在JavaFX上开发应用程序的常见模式。我想我正在寻求一个Java最佳实践来关闭基于UI的应用程序中的依赖进程，比如这个应用程序类（在这种情况下：基于FXML/JavaFX），其中有一个控制器类和一个应用程序类。

你能解释我做错了什么吗？或更好：建议我应该在做什么呢？谢谢。

在我的应用我这样做：

public class MyApp extends Application { 

    @Override 
    public void start(Stage primaryStage) throws Exception { 
     FXMLLoader fxmlLoader = new FXMLLoader(); 
     Scene scene = (Scene)FXMLLoader.load(getClass().getResource("MyApp.fxml")); 
     MyAppController myController = (MyAppController)fxmlLoader.getController(); 

     primaryStage.setScene(scene); 
     primaryStage.show(); 

//  myController.setApp(this); 
    } 

    @Override 
    public void stop() throws Exception { 
//  super.stop(); 

     // this is called on fx app close, you may call it in an action handler too 
     if (MyAppController.getScriptProcess() != null) { 
     MyAppController.getScriptProcess().destroy(); 
     } 
     super.stop(); 
    } 
    public static void main(String[] args) { 
     launch(args); 
    } 
}

在我的控制器我这样做：

public class MyAppController implements Initializable { 

    private Application app; 
    private static Process scriptProcess; 


    public void setApp(Application a) { 
    app = a; 
    } 

    public static Process getScriptProcess() { 
    return scriptProcess; 
    } 
}

结果，当我用 “注释掉setApp（）” 不运行注意到（即在启动方法中留下的）如下，启动后立即（主场景闪烁，然后消失，然后出现此对话框：

"JavaFX Launcher Error: 
Exception while running Application"

它还在控制台中给出了“应用程序启动方法中的异常”。

结果，当我在MyApp的上方留下了“注释掉的代码”（即，从一开始的方法去除“setApp（）”），是我的应用程序确实确实接近，但给这个错误当它关闭时：

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException 
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1440) 
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170) 
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53) 
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28) 
    at javafx.event.Event.fireEvent(Event.java:171) 
    at javafx.scene.Node.fireEvent(Node.java:6863) 
    at javafx.scene.control.Button.fire(Button.java:179) 
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193) 
    at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336) 
    at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329) 
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170) 
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) 
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53) 
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33) 
    at javafx.event.Event.fireEvent(Event.java:171) 
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3324) 
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3164) 
    at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3119) 
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1559) 
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2261) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:228) 
    at com.sun.glass.ui.View.handleMouseEvent(View.java:528) 
    at com.sun.glass.ui.View.notifyMouse(View.java:922) 
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) 
    at com.sun.glass.ui.gtk.GtkApplication$3$1.run(GtkApplication.java:82) 
    at java.lang.Thread.run(Thread.java:722) 
Caused by: java.lang.reflect.InvocationTargetException 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1435) 
    ... 44 more 
Caused by: java.lang.NullPointerException 
    at mypackage.MyController.handleCancel(MyController.java:300) 
    ... 49 more 
Clean up...

来源

2012-09-11 likethesky

该方法是正确的，但几乎没有问题。

你已经创建了名为fxmlLoader的FXMLLoader，但是你可以调用FXMLLoader.load()这是一种静态方法，并且与以前创建的实例没有关联。

同样使用静态方法进行互通并不是很好（想象一下你会想要有几个进程）。将myController更好地存储到字段中，并在stop()方法中调用它。

更好的办法是将相应的实用程序方法添加到控制器并从主应用程序调用它，因为主应用程序本身似乎并不使用Process。

这里不用短应用证明所有描述：

public class DoTextAreaLog extends Application { 

    private LoggController controller; 

    @Override 
    public void start(Stage stage) throws IOException{ 
      FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("logg.fxml")); 
      VBox root = (VBox)fxmlLoader.load(); 
      controller = (LoggController) fxmlLoader.getController(); 

      stage.setScene(new Scene(root, 400, 300)); 
      stage.show(); 
    } 

    @Override 
    public void stop() throws Exception { 
     super.stop(); 
     controller.destroy(); 
    } 

    public static void main(String[] args) { launch(); } 
}

控制器：

public class LoggController implements Initializable { 

    @FXML private TextArea textarea; 

    @FXML private void onAction(ActionEvent event) { 
     destroy(); 
    } 

    private Process p; 

    public void destroy() { 
     if (p != null) { 
      p.destroy(); 
     } 
    } 

    @Override 
    public void initialize(URL url, ResourceBundle rb) { 
     try { 
      p = new ProcessBuilder("ping", "stackoverflow.com", "-n", "100").start(); 

      new Thread(new Runnable() { 
       @Override 
       public void run() { 
        try { 
         try (BufferedReader bri = new BufferedReader(new InputStreamReader(p.getInputStream()))) { 
          String line; 

          while ((line = bri.readLine()) != null) { 
           log(line); 
          } 
         } 
        } catch (IOException ex) { 
         ex.printStackTrace(); 
        } 
       } 
      }).start(); 
     } catch (IOException ex) { 
      ex.printStackTrace(); 
     } 
    } 

    private void log(final String st) { 
     Platform.runLater(new Runnable() { 
      @Override 
      public void run() { 
       textarea.setText(st + "\n" + textarea.getText()); 
      } 
     }); 
    } 
}

LOGG。fxml：

<VBox id="root" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml" fx:controller="fxml.LoggController"> 
    <TextArea fx:id="textarea"/> 
    <Button text="Stop The Madness!" onAction="#onAction"/> 
</VBox>

来源

2012-09-11 09:36:51

FXMLLoader fxmlLoader = new FXMLLoader（getClass（）。getResource（“logg.fxml”））;不适用于我，我得到一个错误，即FXMLLoader（URL）没有合适的构造器，虽然有。我不明白这个原因。 – glasspill

请提出这个问题作为一个单独的问题，提供你的代码，你正在使用的JavaFX的完整例外和版本。 –

JavaFX应用程序和控制器类之间的FXML通信

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