从其控制器 JavaFX 外部访问节点 - MVC

Question

我正在构建一个天气应用程序。有 2 个场景和 2 个控制器文件。一个是主屏幕，另一个是“设置”。主 FXML 包含一个标签，如果用户不想看到额外的信息，则必须在设置页面中打开/关闭该标签。我的问题是如果可能的话，如何从设置页面的控制器类中设置该标签。 感谢您的帮助

Answer 1

我假设设置场景仅在用户单击主屏幕上的按钮时出现。我最近不得不在我的代码中处理同样的情况。这是处理这种情况的一个很好的教程：

http://code.makery.ch/library/javafx-2-tutorial/part1/

1.) 在您的 MainScene 控制器中，您将引用主类并调用其函数以弹出设置场景。

2.) 在您的主类中，您将拥有一个弹出设置场景的功能

3.) 设置场景关闭后，它会通过 Main 类将值传回 MainScene 控制器，并根据返回的值设置标签。

1.) Main 场景的 MainController 将具有对主类的引用和一个通过主类调用设置场景的函数。

public class MainController {

@FXML
private Label label;
@FXML
private Button Settings;


// Reference to the main application
private MainApp mainApp;

/**
 * The constructor.
 * The constructor is called before the initialize() method.
 */
public MainController() {
}

/*Tie this function to your button that pops up Settings */

private void handleSettingsButton() { 

      /* Here you call a function in the main class and pass the label
       * to the settings scene controller */

        boolean show = mainApp.showSettingsScene(label);
        if (show) {
                label.isVisible("True");
         }
        else {
                label.isVisible("False");
        }
}

/**
 * Is called by the main application to give a reference back to itself.
 * 
 * @param mainApp
 */
public void setMainApp(MainApp mainApp) {
    this.mainApp = mainApp;


}
}

2.) 在您的主类（不要与主场景混淆）中，您加载主场景并调用 setMainApp 函数为您的控制器提供对主类的引用。

    public class MainApp extends Application {

private Stage primaryStage;
private BorderPane rootLayout;

@Override
public void start(Stage primaryStage) {
    this.primaryStage = primaryStage;
    this.primaryStage.setTitle("Main");

 /*Right when the app is loaded the MainScene shows up.*/

    try {
        // Load the root layout from the fxml file
        FXMLLoader loader = new FXMLLoader(MainApp.class.getResource("view/MainScene.fxml"));
 /* Get a reference to the controller instance of the main Scene */
mainSceneController = loader.getController();
    /*Allow the controller to talk to the main class */
    mainSceneController.setMainApp(this);
        rootLayout = (BorderPane) loader.load();
        Scene scene = new Scene(rootLayout);
        primaryStage.setScene(scene);
        primaryStage.show();
    } catch (IOException e) {
        // Exception gets thrown if the fxml file could not be loaded
        e.printStackTrace();
    }


}

/**
 * Returns the main stage.
 * @return
 */
public Stage getPrimaryStage() {
    return primaryStage;
}

/*This function referenced in your main controller will show the Settings
 *Scene and wait to see what the user has selected for the visible or not 
 *visible selection.  We need to pass the label to it as well, so we
 *accurately load the Settings Scene with the current state of the label
 */

public boolean showSettingsScene(Label label) {
    try {
      // Load the fxml file and create a new stage for the popup
    FXMLLoader loader = new FXMLLoader(MainApp.class.getResource("view/SettingsScene.fxml"));
settingsSceneController = loader.getController();

    /* Here we send the label to the controller instance of the Settings
     * Scene */

    controller.setLabel(label);
    AnchorPane page = (AnchorPane) loader.load();
    Stage dialogStage = new Stage();
    dialogStage.setTitle("Settings");
    dialogStage.initModality(Modality.WINDOW_MODAL);
    dialogStage.initOwner(primaryStage);
    Scene scene = new Scene(page);
    dialogStage.setScene(scene);

/* Show the dialog and wait until the user closes it*/
dialogStage.showAndWait();

 /*Return the value that the user has selected for visible or not */
return controller.isShowOrHide();

   } catch (IOException e) {
// Exception gets thrown if the fxml file could not be loaded
e.printStackTrace();
     return false;
   }
 }

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

3.) 您的设置场景控制器将如下所示：

import...
public class SettingsSceneController{

@FXML  private ComboBox showOrHide;

private Stage dialogStage;
private Boolean show = false;
private Label label;

/**
 * Initializes the controller class. This method is automatically called
 * after the fxml file has been loaded.  
 */
@FXML
private void initialize() {
     ;I don't know what you have, but if you use a Combobox...
     showOrHide.getItems().addAll(
          "Show",
          "Hide",);

}

/**
 * Sets the stage of this dialog.
 * @param dialogStage
 */
public void setDialogStage(Stage dialogStage) {
    this.dialogStage = dialogStage;
}

/*The label that was passed from Main Scene Controller to Main Class to 
 * here is now used in the function to update the Combobox with the
 * current status of the label */
public void setLabel(Label label) {
    this.label = label;
     if(label.isVisible){
          showOrHide.setValue("Show");
          show = true;
     }
     else{
          showOrHide.setValue("Hide"); 
          show = false;
     }
}



/**
 * Returns true if the user clicked OK, false otherwise.
 * @return
 */
public boolean isShowOrHide() {
    return show;
}

/**
 * Called when the user clicks ok. Attach this in Scene Builder,to the OK,
 * Enter or Apply or whatever you called it button of the Settings Scene 
 * It will reflect any change made to the combobox.
 */
@FXML
private void handleOk() {
    if (showOrHide.getValue().toString() == "Show") {
        show= true;
     }
    else{
        show = false;
     }
        dialogStage.close();

}

/**
 * Called when the user clicks cancel if you have a cancel button.
 */
@FXML
private void handleCancel() {
    dialogStage.close();
}


}
}

我从教程中获取了大部分代码，并根据您的解决方案对其进行了定制。它有点像三个类，但如果你稍微思考一下，你会看到它们是如何使用主类在控制器之间进行通信以促进它的。我没有对此进行测试，但它应该非常接近您的需要。