JavaFX JSObject stop working after a few minutes?

问题

I'm making a web based app with Java support for some particular requests (e.g. print without choosing the printer everytime) and there is something that id driving me crazy.

I use JavaFX for instantiate the browser object and everything works fine, but of course I need to make callbacks from JavaScript to Java, here is the code:

...
...
we.getLoadWorker().stateProperty().addListener( new ChangeListener<Worker.State>()
    {
        @Override
        public void changed(ObservableValue<? extends State> observable, State oldValue, State newValue)
        {
            if ( newValue == Worker.State.SUCCEEDED )
            {
                bridge = new Bridge();
                JSObject jsobj = (JSObject) we.executeScript( "window" );
                jsobj.setMember( "app", new Bridge() );
            }

            if ( newValue == Worker.State.CANCELLED )
            {
                System.out.println( newValue );
                System.out.println( "An error accourred" );
            }
        }
    });
    ...
    ...

This works but after a few minutesthe bridge stoo working totally, javascript can't make callbacks anymore and if I try to make an alert() on the "app" object it return me undefined. I'm using JDK9

回答1:

To make the solution more obvious: the approach suggested by @sillyfly works.

Instead of creating a new Bridge (or in my case Console) instance for every state change, make a single instance and reassign it every time. Something along the following lines.

public class AppController {
    public WebView webview;

    @FXML
    public void initialize() {
        final Console console = new Console();
        final WebEngine engine = webview.getEngine();
        engine.setJavaScriptEnabled(true);
        engine.getLoadWorker().stateProperty().addListener(new ChangeListener<Worker.State>() {
            @Override
            public void changed(ObservableValue<? extends Worker.State> observable, Worker.State oldValue, Worker.State newValue) {
                final JSObject window = (JSObject) engine.executeScript("window");
                window.setMember("console", console);
            }
        });
    }

    public class Console {
        public void log(String text) {
            System.out.println("[WebView console] " + text);
        }
    }
}

来源：https://stackoverflow.com/questions/46744432/javafx-jsobject-stop-working-after-a-few-minutes

标签

java

javafx

javafx-webengine

jsobject