当我的应用程序失去焦点时如何侦听

Question

我需要在应用程序窗口失去焦点时触发一个事件。我将如何在窗口上为此设置侦听器？

Answer 1

正如上面的评论所暗示的那样，简单地听你的舞台focusedProperty是正确的方法。

请参阅下面的简单示例应用程序以了解其工作原理：

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class WindowFocusExample extends Application {
    public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void start(Stage primaryStage) {
        // Simple interface
        VBox root = new VBox(5);
        root.setPadding(new Insets(10));
        root.setAlignment(Pos.CENTER);
        // A label to show our current focus status
        Label label = new Label("Window has focus.");
        // Let's listen for our window to get/lose focus
        primaryStage.focusedProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue) {
                label.setText("Window HAS focus.");
            } else {
                label.setText("Window has LOST focus!");
            }
            System.out.println(label.getText());
        });
        root.getChildren().add(label);
        // Show the Stage
        primaryStage.setWidth(300);
        primaryStage.setHeight(300);
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }
}