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如何获取包含的FXML的控制器？

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我有一个围绕JavaFXML和scenebuilder构建的简单的两个选项卡应用程序。这些选项卡目前无济于事，因为尝试加载它们时我无法克服nullpointer异常。

Java和fxml文件在Netbeans项目中的排列方式如下：

如何获取包含的FXML的控制器？

主应用程序：应用程序主类MainApp.java设置场景并声明如下：

package tabpane;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import javafx.stage.StageStyle;


public class MainApp extends Application {

  private static Stage primaryStage;
  private AnchorPane rootLayout;  


  public MainApp() {}

  @Override
  public void start(Stage primaryStage) {
    primaryStage.initStyle(StageStyle.UNDECORATED);
    MainApp.primaryStage = primaryStage;
    MainApp.primaryStage.setTitle("account Names");
    initRootLayout();
  }

  public void initRootLayout() {
    try {
      FXMLLoader loader = new FXMLLoader();
      loader.setLocation(MainApp.class.getResource("view/MainView.fxml"));
      rootLayout = (AnchorPane) loader.load(); 
      Scene scene = new Scene(rootLayout);
      primaryStage.setScene(scene);
      primaryStage.show();

    } catch (IOException e) {
        Logger.getLogger(MainApp.class.getName()).log(Level.SEVERE,null,e);
        System.out.println("MainApp: IOException in method: initRootLayout" + e.getMessage());
        system.exit(0);
    }
  }

  public Stage getPrimaryStage() {
    return primaryStage;
  }

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

MainController类为应用程序声明两个选项卡，即“输入”选项卡和“帐户”选项卡，以及用于关闭程序的退出按钮。这是MainView。 fxml文件：

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="tabpane1.view.MainController">
   <children>
      <TabPane fx:id="tabPane" prefHeight="345.0" prefWidth="600.0" style="-fx-background-color: blue;" tabClosingPolicy="UNAVAILABLE">
        <tabs>
          <Tab fx:id="inputTab" closable="false" text="Input">
            <content>
                <fx:include source="InputView.fxml" />
            </content>
          </Tab>
          <Tab fx:id="detailTab" closable="false" text="Detail">
            <content>
               <fx:include source="DetailView.fxml" />
            </content>
          </Tab>
        </tabs>
      </TabPane>
      <Button fx:id="exitBtn" layoutX="529.0" layoutY="355.0" mnemonicParsing="false" onaction="#handleExitBtn" text="Exit" />
   </children>
</AnchorPane>

这是MainController.java中包含的主视图的Java控制器类：

package tabpane1.view;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;

public class MainController implements Initializable    {
    @FXML public TabPane tabPane;
    @FXML public Tab inputTab;
    @FXML public Tab accountTab;
    @FXML private Button exitBtn;

    public DetailController detailController;      
    public InputController inputController;

    @Override
    public void initialize(URL location,ResourceBundle resources) { 
      detailController = new FXMLLoader(getclass().getResource("DetailView.fxml")).getcontroller(); 
//      System.out.println(detailController.getclass());
      inputController = new FXMLLoader(getclass().getResource("InputView.fxml")).getcontroller(); 
//      System.out.println(inputController.getclass());
    }

    @FXML private void handleExitBtn() {
        system.exit(0);
    }
}

这两个println语句只是试图获取对两个选项卡的引用，它们是detailController和inputController，以执行某些操作。但是，取消注释并运行它们时，将输出以下转储：

MainApp: IOException in method: initRootLayout
SEVERE: null
file:/G:/J2EE/TabPane_1/dist/run1314937364/TabPane_1.jar!/tabpane1/view/MainView.fxml
javafx.fxml.LoadException: 

file:/G:/J2EE/TabPane_1/dist/run1314937364/TabPane_1.jar!/tabpane1/view/MainView.fxml

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409)
    at tabpane1.MainApp.initRootLayout(MainApp.java:43)
    at tabpane1.MainApp.start(MainApp.java:33)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
    at java.security.accessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
    at tabpane1.view.MainController.initialize(MainController.java:24)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    ... 13 more

当注释出printlns时，结果如预期的那样，即正确显示了选项卡窗格：

如何获取包含的FXML的控制器？

如上所述，详细信息和输入控制器为空，但为完整起见，它们如下：

InputView.fxml：

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

<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="tabpane1.view.InputController">

</AnchorPane>

控制器InputController.java：

package tabpane1.view;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.Initializable;

public class InputController implements Initializable   {

  @Override
  public void initialize(URL location,ResourceBundle resources) {}  
}

DetailView.fxml：

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

<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" style="-fx-background-color: transparent;" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="tabpane1.view.DetailController" />

控制器DetailController.java：

package tabpane1.view;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.Initializable;

public class InputController implements Initializable   {

  @Override
  public void initialize(URL location,ResourceBundle resources) {}  
}
longsheng923123 回答：如何获取包含的FXML的控制器？

this article中描述了获取对嵌入式FXML控制器的引用的方法。

您只需为包含的资源提供fx:id：

   <fx:include fx:id="IncludedView" source="InputView.fxml" />

在IncludedView中获得对MainController的引用：

@FXML private Parent IncludedView;

只需在嵌入式元素的变量名后添加控制器一词即可获得对其控制器的引用：

@FXML private InputController IncludedViewController;

仅此而已。

使用以下方法进行测试：

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Parent;

public class MainController implements Initializable    {

    @FXML private Parent IncludedView;
    @FXML private InputController IncludedViewController; // $IncludedView;+Controller

    @Override
    public void initialize(URL location,ResourceBundle resources) {

        System.out.println(IncludedView.getClass());
        System.out.println(IncludedViewController.getClass()    );
    }

    @FXML private void handleExitBtn() {
        System.exit(0);
    }
}

为将来的读者着想的MRE：

import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class GetEmbeddedController extends Application {

    @Override
    public void start(Stage primaryStage) {
        try {
            Pane root = (Pane) FXMLLoader.load(getClass().getResource("MainView.fxml"));
            primaryStage.setScene(new Scene(root));
            primaryStage.show();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }

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

MainView.fxml 

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/10.0.1" 
  xmlns:fx="http://javafx.com/fxml/1" fx:controller="MainController">
   <children>  
      <fx:include fx:id="includedView" source="IncludedView.fxml" />         
      <Button layoutX="401.0" layoutY="354.0" onAction="#handleTestBtn" text="Test Included Controller" />
   </children>
</AnchorPane>

MainController.java 

import javafx.fxml.FXML;
import javafx.scene.Parent;

public class MainController{

    @FXML private Parent includedView; //not used in this demo
    /*
     * Get a reference to IncludedView controller simply by appending
     * the word Controller in addition to the variable name of the embedded
     * element:$IncludedView;+Controller
     */
    @FXML private IncludedViewController includedViewController;

    @FXML private void handleTestBtn() {
        includedViewController.showAlert();
    }
}

IncludedView.fxml 

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

<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Text?>

<AnchorPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/10.0.1" 
xmlns:fx="http://javafx.com/fxml/1" fx:controller="IncludedViewController">
   <children>
      <Text layoutX="277.0" layoutY="196.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Included Fxml" />
   </children>
</AnchorPane>

IncludedViewController.java 

import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;

public class IncludedViewController{

    void showAlert(){
        Alert alert = new Alert(AlertType.INFORMATION);
        alert.setContentText("Alert invoked by IncludedViewController ");
        alert.show();
    }
}
controllerfxmlfxml-includejavajavafx
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