如何在显示窗口之前更改JavaFX中的FXML控制器变量值？

Question

我想在弹出FXML窗口中更改标签和文本，然后再显示它们。这样做是因为所有帮助项都非常相似，我想制作模板FXML，然后相应地更改标签和文本区域的值以减少编码。

我很惊讶我在JavaFX中没有遇到过模板方法。如果有更好的方法，请建议。

对于手头的任务，我有以下内容：

@FXML
private void documentationAction(ActionEvent action) throws IOException {
    Stage dialogue = new Stage();
    Parent root = null;
    FXMLLoader loader = new FXMLLoader();
    root = loader.load(getClass().getResource("dialogues/dialogue.fxml"));
    Scene scene = new Scene(root);
    /*
     * change text values in title (Label) and text (TextArea)
     * and change the behavior of the findMore button
     */
    dialogue.setTitle("Documentation");
    dialogue.setScene(scene);
    dialogue.show();
}

我希望能够更改FXM L文件中的变量，我已在控制器类中为getters和setters创建了变量，但我无法想象这该怎么做。

有办法吗？看起来在多窗口应用程序中更改窗口之间的信息是必要的，所以我确信有一些我想念的简单。

UPDATE 控制器代码：

public class DialogueController implements Initializable {

    @FXML
    private Button more;
    @FXML
    private Button close;
    @FXML
    private TextArea text;
    @FXML
    private Label title;

    public TextArea getText() {
        return text;
    }

    public void setText(String text) {
        this.text.setText(text);
    }

    public Label getTitle() {
        return title;
    }

    public void setTitle(String text) {
        this.title.setText(text);
    }

    @FXML
    public void closeAction(ActionEvent action) {
        // get a handle to the stage
        Stage stage = (Stage) close.getScene().getWindow();
        // do what you have to do
        stage.close();
    }

    @FXML
    public void moreAction(ActionEvent action) {
    }

    @FXML
    public void makeDocumentation(ActionEvent action) {
        this.title.setText("Documentation");
    }

    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {
    }
}

Full Dialogue FXML

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.net.*?>
<?import java.util.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" padding="$x1" prefHeight="500.0" prefWidth="400.0" styleClass="mainFxmlClass" xmlns:fx="http://javafx.com/fxml" fx:controller="pdbpro.dialogues.DialogueController">
  <children>
    <GridPane alignment="CENTER" prefHeight="400.0" prefWidth="600.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
      <children>
        <Label fx:id="title" alignment="CENTER_LEFT" prefWidth="-1.0" styleClass="title" text="Title" underline="false" visible="true" GridPane.columnIndex="0" GridPane.rowIndex="0">
          <GridPane.margin>
            <Insets fx:id="x1" />
          </GridPane.margin>
        </Label>
        <TextArea fx:id="text" editable="false" focusTraversable="false" prefWidth="200.0" wrapText="true" GridPane.columnIndex="0" GridPane.rowIndex="1">
          <GridPane.margin>
            <Insets bottom="24.0" left="15.0" right="15.0" />
          </GridPane.margin>
        </TextArea>
        <ToolBar GridPane.columnIndex="0" GridPane.rowIndex="2">
          <items>
            <Button fx:id="more" mnemonicParsing="false" text="Find more" />
            <Button fx:id="close" mnemonicParsing="false" onAction="#closeAction" text="Close" />
          </items>
          <GridPane.margin>
            <Insets bottom="14.0" />
          </GridPane.margin>
        </ToolBar>
      </children>
      <columnConstraints>
        <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
      </columnConstraints>
      <padding>
        <Insets fx:id="x1" />
      </padding>
      <rowConstraints>
        <RowConstraints maxHeight="60.0" minHeight="60.0" prefHeight="60.0" valignment="CENTER" vgrow="NEVER" />
        <RowConstraints maxHeight="1.7976931348623157E308" minHeight="50.0" prefHeight="0.0" vgrow="ALWAYS" />
        <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
      </rowConstraints>
    </GridPane>
  </children>
  <stylesheets>
    <URL value="@dialogue.css" />
  </stylesheets>
</AnchorPane>

这些行的完整堆栈错误

FXMLLoader loader = new FXMLLoader();
Parent root = loader.load(getClass().getResource("dialogues/dialogue.fxml"));
DialogueController dc = loader.getController();
dc.makeDocumentation(); //ERROR
Scene scene = new Scene(root);


java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1440)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.control.MenuItem.fire(MenuItem.java:456)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1188)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1139)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1137)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3324)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3164)
    at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3119)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1559)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2261)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:228)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
    at com.sun.glass.ui.View.notifyMouse(View.java:922)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
    at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1435)
    ... 37 more
Caused by: java.lang.NullPointerException
    at pdbpro.MainController.documentationAction(MainController.java:82)
    ... 42 more

Answer 1

我可以看到的一种方法是使控制器实现可初始化并实现initialize方法。当fxml加载器创建控制器时，将自动调用initialize方法。当调用inititialize方法时，所有声明的fxml对象都应该被初始化并准备好进行自定义。

[编辑] 看完docs for initializable后， 它表示如果创建一个名为initialize而没有args的方法，它将使用fxml加载器自动调用。因此，根据我的理解，您不需要实现可初始化。只需创建一个没有args的initialize方法。

如果需要，可以在an introduction to fxml中找到更多信息。

Answer 2

试试这个：

root = (Parent) loader.load(getClass().getResource("dialogues/dialogue.fxml").openStream());
DialogueController dc = loader.getController();
dc.setTitle("title");
dc.setTextArea("text");
// and so on..
...
dialogue.show();

断言DialogueController dc不为null。假设“title”是带有fx:id=titleLabel的fxml文件中的Label，它应该在您的控制器类中支持，如下所示：

...
@FXML private Label titleLabel;
...
public void setTitle(String txt) {
    titleLabel.setText(txt);
}
...

Answer 3

我建议你将所有FXML加载代码隐藏到控制器中。为此，可以扩展Stage类：

控制器：

public class DialogueController extends Stage implements Initializable{
    @FXML private Button more;
    @FXML private Button close;
    @FXML private TextArea text;
    @FXML private Label title;

    public DialogueController(Parent parent){
        FXMLLoader loader = new FXMLLoader(getClass().getResource("dialogues/dialogue.fxml"));
        fxmlLoader.setController(this);
        super.setTitle("Documentation");
        try{
            setScene(new Scene((Parent) loader.load()));
        }catch(IOException e){
            e.printStackTrace();        
        }
        /*
         * Change values here
         */     
    }   
}

致电您的控制器：

@FXML
private void documantationAction(ActionEvent action) throws IOException{
    DialogueController controller = new DialogueController(null);
    controller.show();
}