应用和控制器类之间的JavaFX FXML通信(JavaFX FXML communication

2019-06-28 03:48发布

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我想获得和破坏我在我的FXML应用程序关闭通过创建的ProcessBuilder外部进程，但它不工作。 这是基于有用的建议谢尔盖Grinev给了我这里 。

我曾尝试与运行/无“// myController.setApp（本）;” 并用 “// super.stop（）;” 在子类的顶部和底部处（参见/中注释掉在MyApp的那条线），但没有结合的作品。

这可能是不相关的FXML或JavaFX的，但我想这是对的JavaFX开发应用程序的通用模式。 我想，我要求在一个基于用户界面的应用程序关闭相关进程像这样的一个Java最佳实践（在这种情况下：基于FXML / JavaFX的），那里有一个控制器类和应用类。

你能解释一下我做错了什么？ 或者更好的建议我应该怎么做，而不是？ 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;
  }
}

结果当我运行“注释掉setApp（）” 没有被注释掉（即，留在启动方法），如下，启动后立即（主场景闪烁，然后消失，然后出现这个对话框： 

"JavaFX Launcher Error:
Exception while running Application"

它给出了一个，在控制台“在应用启动方法异常”的可能。

结果，当我离开了“注释掉的代码”在我MyApp的上方（也就是，从一开始的方法去除“setApp（）”），是我的应用程序确实接近，但它关闭时给出了这样的错误： 

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...

Answer 1:

方法是正确的，但也存在一些问题。

您所创建的FXMLLoader命名fxmlLoader但然后调用FXMLLoader.load()是静态的方法，而不是用你以前创建的实例连接。

还采用静态方法来互通不是很好（想象一下，你会想有几个进程）。 更好地存储myController一个领域，并调用它的stop()方法。

更妙的是添加相应的实用方法控制器和从主应用程序调用它，因为主要的应用程序似乎并不使用Process本身。

这里去短应用演示所有描述： 

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>


文章来源: JavaFX FXML communication between Application and Controller classes
标签： javafx-2 processbuilder fxml
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