Javafx 将参数和值从一个控制器传递到另一个控制器 [英] Javafx pass parameter and values from one controller to another

问题描述

我是 JavaFx 的新手，因此我找不到解决我问题的解决方案

I am new to JavaFx and hence I cannot find a solution to solve my problem

假设我有以下应用程序结构:

Suppose I have following application structure :

- views
      - first.fxml -> this has a button called btnSend and a textfield called txtEnter
      - second.fxml -> this has a textarea called txtView
- Controller 
      - FirstController  -> controller for First
      - SecondController -> controller for second
- Modal
      - AppModal -> here I have a getter and a setter method , 
                    as getText() and setText(String text)

- App
     - Main.java -> This one used FXMLLoader to load first.fxml and second.fxml together.

在从 FirstController 传递的 SecondController 中显示文本的最佳/最佳方式是什么.我的意思是，我在 txtEnter 中输入一个文本，然后按下按钮 btnSend，按下按钮后我希望文本显示在 txtView 中正在使用另一个控制器.我已经阅读了很多关于 observers pattern 和 JavaFX properties 可以用来解决这个问题，但不幸的是我无法实现一个有效的解决方案.

What is the optimal/best way to display the text in SecondController passing it from FirstController. I mean, I enter a text in txtEnter and press the button btnSend and after pressing the button I want the text to be displayed in txtView which is using another controller. I have read a lot about the observers pattern and JavaFX properties can be used to solve this, but unfortunately I am unable to implement a working solution.

如果您的专家能在这方面帮助我，我将不胜感激.我知道它不正确，但任何人都可以为上述项目结构提供一个可行的解决方案.

I would be humbly thankful if you experts can help me in this. I know its not correct but can anyone please give me a working solution for the above project structure.

提前致谢.

推荐答案

在模型中使用可观察的StringProperty:

Use an observable StringProperty in the model:

public class AppModel {

    private final StringProperty text = new SimpleStringProperty();

    public StringProperty textProperty() {
        return text ;
    }

    public final String getText() {
        return textProperty().get();
    }

    public final void setText(String text) {
        textProperty().set(text);
    }
}

让你的控制器可以访问模型:

Make your controllers have access to the model:

public class FirstController {

    private final AppModel model ;

    @FXML
    private TextField textEnter ;

    public FirstController(AppModel model) {
        this.model = model ;
    }

    // action event handler for button:
    @FXML
    private void sendText() { 
        model.setText(textEnter.getText());
    }
}

和

public class SecondController {

    private final AppModel model ;

    @FXML
    private TextArea txtView ;

    public SecondController(AppModel model) {
        this.model = model ;
    }

    public void initialize() {
        // update text area if text in model changes:
        model.textProperty().addListener((obs, oldText, newText) -> 
            txtView.setText(newText));
    }
}

现在稍微有点棘手的部分是控制器没有无参数构造函数，这意味着 FXMLLoader 创建它们的默认机制将不起作用.最简单的方法是手动设置它们.从 FXML 文件中删除 属性，然后在您的 Main 类中执行

The slightly tricky part now is that the controllers don't have a no-arg constructor, which means the default mechanism for the FXMLLoader to create them won't work. The easiest way is to set them manually. Remove both the <fx:controller> attributes from the FXML files, and then in your Main class do

AppModel model = new AppModel();

FXMLLoader firstLoader = new FXMLLoader(getClass().getResource("first.fxml"));
firstLoader.setController(new FirstController(model));
Parent firstUI = firstLoader.load();

FXMLLoader secondLoader = new FXMLLoader(getClass().getResource("second.fxml"));
secondLoader.setController(new SecondController(model));
Parent secondUI = secondLoader.load();

如果您希望在 FXML 文件中保留 <fx:controller> 属性，您可以使用 controllerFactory 代替，它实质上指示 FXMLLoader 关于如何创建控制器:

If you prefer to keep the <fx:controller> attributes in the FXML files, you can use a controllerFactory instead, which essentially instructs the FXMLLoader as to how to create a controller:

AppModel model = new AppModel();

Callback<Class<?>, Object> controllerFactory = type -> {
    if (type == FirstController.class) {
        return new FirstController(model);
    } else if (type == SecondController.class) {
        return new SecondController(model);
    } else {
        try {
            return type.newInstance() ; // default behavior - invoke no-arg construtor
        } catch (Exception exc) {
            System.err.println("Could not create controller for "+type.getName());
            throw new RuntimeException(exc);
        }
    }
};

FXMLLoader firstLoader = new FXMLLoader(getClass().getResource("first.fxml"));
firstLoader.setControllerFactory(controllerFactory);
Parent firstUI = firstLoader.load();

FXMLLoader secondLoader = new FXMLLoader(getClass().getResource("second.fxml"));
secondLoader.setControllerFactory(controllerFactory);
Parent secondUI = secondLoader.load();

您可以通过使用(更多)反射使控制器工厂更加灵活；基本上你可以实现逻辑如果控制器类型有一个采用 AppModel 的构造函数，则调用该构造函数，否则调用无参数构造函数".

You can make the controller factory even more flexible by using (more) reflection; basically you can implement the logic "if the controller type has a constructor taking an AppModel, call that constructor, otherwise call the no-arg constructor".

如果您正在创建一个需要执行大量此类操作的大型应用程序，那么您可以考虑使用 afterburner.fx，这是一个框架，它本质上允许您使用注释将模型注入到控制器中.

If you are creating a large application which needs to do a lot of this, then you might consider using afterburner.fx, which is a framework that essentially allows you to inject the model into the controllers using annotations.

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