从 javafx 平台 runlater 返回结果 [英] Return result from javafx platform runlater

问题描述

我正在开发 JavaFX 应用程序，在我的场景中是显示在 JavaFX 中创建的密码提示，它使用两个选项 OK 和 Cancel 获取密码.我已返回用户输入的密码.

I am working on JavaFX application, in my scenario is to show a password prompt created in JavaFX which takes password with two option OK and Cancel. I have returned the password entered by user.

我显示密码对话框的类是 -

My class of showing password dialog is -

public static String showPasswordDialog(String title, String message, Stage parentStage, double w, double h) {
    try {
        Stage stage = new Stage();
        PasswordDialogController controller = (PasswordDialogController) Utility.replaceScene("Password.fxml", stage);
        passwordDialogController.init(stage, message, "/images/password.png");
        if (parentStage != null) {
            stage.initOwner(parentStage);
        }
        stage.initModality(Modality.WINDOW_MODAL);
        stage.initStyle(StageStyle.UTILITY);
        stage.setResizable(false);
        stage.setWidth(w);
        stage.setHeight(h);                
        stage.showAndWait();
        return controller.getPassword(); 
    } catch (Exception ex) {
         return null;
    }

我的代码在下面显示密码提示，实际上这个提示会显示在其他UI上，所以我需要将它包含在Platform.runlater()中，否则它会抛出Not在 FX 应用程序线程上.我需要显示此密码提示，直到我得到正确的密码提示.如果我在 runlater 中包含显示密码，我如何获取密码的值.

My code where to show password prompt is below, actually this prompt will be shown over other UI, so I need to inclose this inside Platform.runlater(), otherwise it throws Not on FX application thread. I need this password prompt to be shown until I get correct one. How can I get value of password if I inclosed showing password inside runlater.

还有其他更好的方法吗?

Is there any other better way?

final String sPassword = null;

          do {
            Platform.runLater(new Runnable() {

                @Override
                public void run() {
                     sPassword = JavaFXDialog.showPasswordDialog(sTaskName + "Password", "Enter the password:", parentStage, 400.0, 160.0);
                }
            });

            if (sPassword == null) {
                System.out.println("Entering password cancelled.");
                throw new Exception("Cancel");
            }
        } while (sPassword.equalsIgnoreCase(""));

推荐答案

我建议将代码包装在 FutureTask 对象中.FutureTask 是一种有用的构造(除其他外)，用于在一个线程(通常是工作线程，在您的情况下是事件队列)上执行部分代码并在另一个线程上安全地检索它.FutureTask#get 将阻塞，直到 FutureTask#run 被调用，因此您的密码提示可能如下所示:

I'd recommend wrapping the code within a FutureTask object. FutureTask is a construct useful (among other things) for executing a portion of code on one thread (usually a worker, in your case the event queue) and safely retrieving it on another. FutureTask#get will block until FutureTask#run has been invoked, therefore your password prompt could look like this:

final FutureTask query = new FutureTask(new Callable() {
    @Override
    public Object call() throws Exception {
        return queryPassword();
    }
});
Platform.runLater(query);
System.out.println(query.get());

由于FutureTask 实现了Runnable，您可以将其直接传递给Platform#runLater(...).queryPassword() 将在事件队列中被调用，随后的 get 调用将被阻塞，直到该方法完成.当然，您会希望循环调用此代码，直到密码实际匹配为止.

As FutureTask implements Runnable, you can pass it directly to Platform#runLater(...). queryPassword() will be inokved on the event queue, and the subsequent call to get block until that method completes. Of course, you will want to invoke this code in a loop until the password actually matches.

这篇关于从 javafx 平台 runlater 返回结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！