如何在java中多次调用launch（） [英] How to call launch() more than once in java

问题描述

如何在java中多次调用launch（）我被赋予异常主要错误：java.lang.IllegalStateException：不能多次调用应用程序启动

How to call the launch() more than once in java i am given an exception as "ERROR IN MAIN:java.lang.IllegalStateException: Application launch must not be called more than once"

我在我的java应用程序中创建了rest cleint，当请求到来时，调用javafx并在完成webview operarion后使用Platform.exit（）方法关闭javafx窗口时打开webview。当第二个请求收到此错误时如何重新发生此错误。

I have create rest cleint in my java application when request comes it call javafx and opening webview after completing webview operarion am closing javafx windows using Platform.exit() method. when second request comes am getting this error how to reslove this error.

JavaFx应用程序代码：

JavaFx Application Code:

public class AppWebview extends Application  {

    public static Stage stage;

    @Override
    public void start(Stage _stage) throws Exception {

        stage = _stage;
        StackPane root = new StackPane();

        WebView view = new WebView();

        WebEngine engine = view.getEngine();
        engine.load(PaymentServerRestAPI.BROWSER_URL);
        root.getChildren().add(view);
        engine.setJavaScriptEnabled(true);
        Scene scene = new Scene(root, 800, 600);
        stage.setScene(scene);

        engine.setOnResized(new EventHandler<WebEvent<Rectangle2D>>() {
            public void handle(WebEvent<Rectangle2D> ev) {
                Rectangle2D r = ev.getData();
                stage.setWidth(r.getWidth());
                stage.setHeight(r.getHeight());
            }
        });

        JSObject window = (JSObject) engine.executeScript("window");
        window.setMember("app", new BrowserApp());

        stage.show();

    }

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

RestClient方法：
调用JavaFX应用程序

RestClient Method: Calling to JavaFX application

// method 1 to lanch javafx
javafx.application.Application.launch(AppWebview.class);

// method 2 to lanch javafx
String[] arguments = new String[] {"123"};
AppWebview .main(arguments);

推荐答案

你不能打电话给 不止一次在JavaFX应用程序上启动（） ，这是不允许的。

You can't call launch() on a JavaFX application more than once, it's not allowed.

来自javadoc：

It must not be called more than once or an exception will be thrown.

建议定期显示窗口

1. 只需拨打 Application.launch（）一次。


2. 使用 Platform.setImplicitExit（false） ，以便在隐藏最后一个应用程序窗口时JavaFX不会自动关闭。


3. 下次需要另一个窗口时，请打开窗口 show（） 在 Platform.runLater（） ，以便在JavaFX应用程序线程上执行调用。

1. Just call Application.launch() once.
2. Keep the JavaFX runtime running in the background using Platform.setImplicitExit(false), so that JavaFX does not shutdown automatically when you hide the last application window.
3. The next time you need another window, wrap the window show() call in Platform.runLater(), so that the call gets executed on the JavaFX application thread.

如果要混合Swing，可以使用 JFXPanel 而不是应用程序，但使用模式与上面概述的类似。

If you are mixing Swing you can use a JFXPanel instead of an Application, but the usage pattern will be similar to that outlined above.

Wumpus示例

import javafx.animation.PauseTransition;
import javafx.application.*;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.stage.Stage;
import javafx.util.Duration;

import java.util.*;

// hunt the Wumpus....
public class Wumpus extends Application {
    private static final Insets SAFETY_ZONE = new Insets(10);
    private Label cowerInFear = new Label();
    private Stage mainStage;

    @Override
    public void start(final Stage stage) {
        // wumpus rulez
        mainStage = stage;
        mainStage.setAlwaysOnTop(true);

        // the wumpus doesn't leave when the last stage is hidden.
        Platform.setImplicitExit(false);

        // the savage Wumpus will attack
        // in the background when we least expect
        // (at regular intervals ;-).
        Timer timer = new Timer();
        timer.schedule(new WumpusAttack(), 0, 5_000);

        // every time we cower in fear
        // from the last savage attack
        // the wumpus will hide two seconds later.
        cowerInFear.setPadding(SAFETY_ZONE);
        cowerInFear.textProperty().addListener((observable, oldValue, newValue) -> {
            PauseTransition pause = new PauseTransition(
                    Duration.seconds(2)
            );
            pause.setOnFinished(event -> stage.hide());
            pause.play();
        });

        // when we just can't take it  anymore,
        // a simple click will quiet the Wumpus,
        // but you have to be quick...
        cowerInFear.setOnMouseClicked(event -> {
            timer.cancel();
            Platform.exit();
        });

        stage.setScene(new Scene(cowerInFear));
    }

    // it's so scary...
    public class WumpusAttack extends TimerTask {
        private String[] attacks = {
                "hugs you",
                "reads you a bedtime story",
                "sings you a lullaby",
                "puts you to sleep"
        };

        // the restaurant at the end of the universe.
        private Random random = new Random(42);

        @Override
        public void run() {
            // use runlater when we mess with the scene graph,
            // so we don't cross the streams, as that would be bad.
            Platform.runLater(() -> {
                cowerInFear.setText("The Wumpus " + nextAttack() + "!");
                mainStage.sizeToScene();
                mainStage.show();
            });
        }

        private String nextAttack() {
            return attacks[random.nextInt(attacks.length)];
        }
    }

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

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