为什么我看不到运行JavaFX Web视图的URL网站？

Question

运行代码时，应该给我一个GUI窗口，其中包含oracle.com网站。但是，当我运行代码时，只剩下一个空白屏幕。我尝试使用其他网站，但没有一个成功。另外，我正在Windows操作系统上运行此代码。

代码：

package sample;

import javafx.beans.value.ChangeListener;
import javafx.application.Application;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
import javafx.scene.web.WebEngine;
import static javafx.concurrent.Worker.State;

public class Main extends Application
{
    public static void main(String[] args)
    {
        Application.launch(args);
    }

    @Override
    public void start(final Stage stage)
    {
        // Create the WebView
        WebView webView = new WebView();

        // Create the WebEngine
        final WebEngine webEngine = webView.getEngine();

        // LOad the Start-Page
        webEngine.load("http://www.oracle.com");

        // Update the stage title when a new web page title is available
        webEngine.getLoadWorker().stateProperty().addListener(new ChangeListener<State>()
        {
            public void changed(ObservableValue<? extends State> ov, State oldState, State newState)
            {
                if (newState == State.SUCCEEDED)
                {
                    //stage.setTitle(webEngine.getLocation());
                    stage.setTitle(webEngine.getTitle());
                }
            }
        });

        // Create the VBox
        VBox root = new VBox();
        // Add the WebView to the VBox
        root.getChildren().add(webView);

        // Set the Style-properties of the VBox
        root.setStyle("-fx-padding: 10;" +
                "-fx-border-style: solid inside;" +
                "-fx-border-width: 2;" +
                "-fx-border-insets: 5;" +
                "-fx-border-radius: 5;" +
                "-fx-border-color: blue;");

        // Create the Scene
        Scene scene = new Scene(root);
        // Add  the Scene to the Stage
        stage.setScene(scene);
        // Display the Stage
        stage.show();
    }
}