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，因此找不到解决方案来解决我的问题

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SecondController中显示从FirstController传递的文本的最佳/最佳方式是什么。我的意思是，我在 txtEnter 中输入文本，然后按按钮 btnSend ，然后按下按钮我想要的文本显示在使用另一个控制器的 txtView 中。
我已经阅读了很多关于 observers模式和的JavaFX属性可以用来解决这个问题，不幸的是我无法实现一个工作的解决方案。

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.

如果您的专家可以帮助我，我会非常感激。我知道它不正确，但任何人都可以给我一个工作解决方案的上述项目结构。

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.

提前感谢。

推荐答案

使用observable StringProperty 在模型中：

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);
    }
}

让您的控制器可以访问模型： p>

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));
    }
}

现在有些棘手的部分是， t有一个无参构造函数，这意味着 FXMLLoader 创建它们的默认机制将无法工作。最简单的方法是手动设置它们。 从FXML文件中删除< fx：controller> 属性，然后在主 class do

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();

如果您希望保留< fx：controller> 属性在FXML文件中，您可以使用 controllerFactory ，这本质上指示 FXMLLoader 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();

您可以使用更多的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构造函数采取 AppModel ，调用该构造函数，否则调用no-arg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做大量工作的大型应用程序，那么您可以考虑使用 afterburner.fx ，这是一个框架，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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