JavaFX如何关闭在SimpleObjectProperty <>（）中创建的文件，

Question

我真的很困惑，我在javaFx中有一个pdf查看器应用程序，

我的问题是，我将创建一个使用closeFile（）方法关闭currentFile的按钮。所以我写了currentFile.set（null）;

我在fxml文件中获得（X）按钮的按钮，关闭该文件，但是如果我加载另一个文件，则分页不起作用，请附上源代码和视频。

Controller.java

package pdfviewer;

import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.io.StringWriter;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Paths;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;

import com.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFPage;

import javafx.beans.binding.Bindings;
import javafx.beans.binding.IntegerBinding;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.concurrent.Task;
import javafx.concurrent.WorkerStateEvent;
import javafx.embed.swing.SwingFXUtils;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.Pagination;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.TitledPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.FileChooser;
import javafx.stage.FileChooser.ExtensionFilter;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.stage.Window;
import javafx.util.Callback;

public class Controller {

    @FXML private Pagination pagination ;
    @FXML private Label currentZoomLabel ;

    private FileChooser fileChooser ;
    private ObjectProperty<PDFFile> currentFile ;
    private ObjectProperty<ImageView> currentImage ;
    @FXML  private ScrollPane scroller ;
    private DoubleProperty zoom ;
    private PageDimensions currentPageDimensions ;

    private ExecutorService imageLoadService ;

    private static final double ZOOM_DELTA = 1.05 ;

    @FXML private Button previousButton,nextButton;

    // ************ Initialization *************

    public void initialize() {

        createAndConfigureImageLoadService();
        createAndConfigureFileChooser();

        currentFile = new SimpleObjectProperty<>();
        updateWindowTitleWhenFileChanges();

        currentImage = new SimpleObjectProperty<>();
        scroller.contentProperty().bind(currentImage);

        zoom = new SimpleDoubleProperty(1);
        // To implement zooming, we just get a new image from the PDFFile each time.
        // This seems to perform well in some basic tests but may need to be improved
        // E.g. load a larger image and scale in the ImageView, loading a new image only
        // when required.
        zoom.addListener(new ChangeListener<Number>() {
            @Override
            public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
                updateImage(pagination.getCurrentPageIndex());
            }
        });

        currentZoomLabel.textProperty().bind(Bindings.format("%.0f %%", zoom.multiply(100)));

        bindPaginationToCurrentFile();
        createPaginationPageFactory();
    }

    private void createAndConfigureImageLoadService() {
        imageLoadService = Executors.newSingleThreadExecutor(new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                Thread thread = new Thread(r);
                thread.setDaemon(true);
                return thread;
            }
        });
    }

    private void createAndConfigureFileChooser() {
        fileChooser = new FileChooser();
        fileChooser.setInitialDirectory(Paths.get(System.getProperty("user.home")).toFile());
        fileChooser.getExtensionFilters().add(new ExtensionFilter("PDF Files", "*.pdf", "*.PDF"));
    }

    private void updateWindowTitleWhenFileChanges() {
        currentFile.addListener(new ChangeListener<PDFFile>() {
            @Override
            public void changed(ObservableValue<? extends PDFFile> observable, PDFFile oldFile, PDFFile newFile) {
                try {
                    String title = newFile == null ? "PDF Viewer" : newFile.getStringMetadata("Title") ;
                    Window window = pagination.getScene().getWindow();
                    if (window instanceof Stage) {
                        ((Stage)window).setTitle(title);
                    }
                } catch (IOException e) {
                    showErrorMessage("Could not read title from pdf file", e);
                }
            }

        });
    }

    private void bindPaginationToCurrentFile() {
        currentFile.addListener(new ChangeListener<PDFFile>() {
            @Override
            public void changed(ObservableValue<? extends PDFFile> observable, PDFFile oldFile, PDFFile newFile) {
                if (newFile != null) {
                    pagination.setCurrentPageIndex(0);
                } 
            }
        });
        pagination.pageCountProperty().bind(new IntegerBinding() {
            {
                super.bind(currentFile);
            }
            @Override
            protected int computeValue() {
                return currentFile.get()==null ? 0 : currentFile.get().getNumPages() ;
            }
        });

        pagination.disableProperty().bind(Bindings.isNull(currentFile));
    }

    private void createPaginationPageFactory() {
        pagination.setPageFactory(new Callback<Integer, Node>() {
            @Override
            public Node call(Integer pageNumber) {
                if (currentFile.get() == null) {

                    return null ;
                } else {
                    if (pageNumber >= currentFile.get().getNumPages() || pageNumber < 0) {
                        return null ;
                    } else {
                        if(pageNumber==0) {previousButton.setDisable(true);}
                        else {previousButton.setDisable(false);}
                        if(pageNumber==currentFile.get().getNumPages()-1) {nextButton.setDisable(true);}
                        else {nextButton.setDisable(false);}
                        updateImage(pageNumber);
                        return scroller ;
                    }
                }
            }
        });
    }

    // ************** Event Handlers ****************

    @FXML private void loadFile() {
        final File file = fileChooser.showOpenDialog(pagination.getScene().getWindow());
        if (file != null) {
            final Task<PDFFile> loadFileTask = new Task<PDFFile>() {
                @Override
                protected PDFFile call() throws Exception {
                    try ( 
                            RandomAccessFile raf = new RandomAccessFile(file, "r");
                            FileChannel channel = raf.getChannel() 
                        ) {
                        ByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
                        return new PDFFile(buffer);
                    }
                }
            };
            loadFileTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
                @Override
                public void handle(WorkerStateEvent event) {
                    pagination.getScene().getRoot().setDisable(false);
                    final PDFFile pdfFile = loadFileTask.getValue();
                    currentFile.set(pdfFile);
                }
            });
            loadFileTask.setOnFailed(new EventHandler<WorkerStateEvent>() {
                @Override
                public void handle(WorkerStateEvent event) {
                    pagination.getScene().getRoot().setDisable(false);
                    showErrorMessage("Could not load file "+file.getName(), loadFileTask.getException());
                }
            });
            pagination.getScene().getRoot().setDisable(true);
            imageLoadService.submit(loadFileTask);
        }
    }
    @FXML private void openPdfOne() {
        //final File file = new File ("C:\\Users\\piratack007\\Desktop\\interaction-fer-et-microbiote.pdf");

        pagination.setCurrentPageIndex(4);
    }

    @FXML private void closeFile() {

        currentFile.set(null);
    }
    @FXML private void nextPage() {
        int pageActuelle=pagination.getCurrentPageIndex();
        pagination.setCurrentPageIndex(pageActuelle+1);
    }
    @FXML private void previousPage() {
        int pageActuelle=pagination.getCurrentPageIndex();
        pagination.setCurrentPageIndex(pageActuelle-1);
    }


    @FXML private void zoomIn() {
        zoom.set(zoom.get()*ZOOM_DELTA);
    }

    @FXML private void zoomOut() {
        zoom.set(zoom.get()/ZOOM_DELTA);
    }

    @FXML private void zoomFit() {
        // TODO: the -20 is a kludge to account for the width of the scrollbars, if showing.
        double horizZoom = (scroller.getWidth()-20) / currentPageDimensions.width ;
        double verticalZoom = (scroller.getHeight()-20) / currentPageDimensions.height ;
        zoom.set(Math.min(horizZoom, verticalZoom));
    }

    @FXML private void zoomWidth() {
        zoom.set((scroller.getWidth()-20) / currentPageDimensions.width) ;
    }

    // *************** Background image loading ****************

    private void updateImage(final int pageNumber) {
        final Task<ImageView> updateImageTask = new Task<ImageView>() {
            @Override
            protected ImageView call() throws Exception {
                PDFPage page = currentFile.get().getPage(pageNumber+1);
                Rectangle2D bbox = page.getBBox();
                final double actualPageWidth = bbox.getWidth();
                final double actualPageHeight = bbox.getHeight();
                // record page dimensions for zoomToFit and zoomToWidth:
                currentPageDimensions = new PageDimensions(actualPageWidth, actualPageHeight);
                // width and height of image:
                final int width = (int) (actualPageWidth * zoom.get());
                final int height = (int) (actualPageHeight * zoom.get());
                // retrieve image for page:
                // width, height, clip, imageObserver, paintBackground, waitUntilLoaded:
                java.awt.Image awtImage = page.getImage(width, height, bbox, null, true, true); 
                // draw image to buffered image:
                BufferedImage buffImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                buffImage.createGraphics().drawImage(awtImage, 0, 0, null);
                // convert to JavaFX image:
                Image image = SwingFXUtils.toFXImage(buffImage, null);
                // wrap in image view and return:
                ImageView imageView = new ImageView(image);
                imageView.setPreserveRatio(true);
                return imageView ;
            }
        };

        updateImageTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent event) {
                pagination.getScene().getRoot().setDisable(false);
                currentImage.set(updateImageTask.getValue());
            }
        });

        updateImageTask.setOnFailed(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent event) {
                pagination.getScene().getRoot().setDisable(false);
                updateImageTask.getException().printStackTrace();
            }

        });

        pagination.getScene().getRoot().setDisable(true);
        imageLoadService.submit(updateImageTask);
    }

    private void showErrorMessage(String message, Throwable exception) {

        // TODO: move to fxml (or better, use ControlsFX)

        final Stage dialog = new Stage();
        dialog.initOwner(pagination.getScene().getWindow());
        dialog.initStyle(StageStyle.UNDECORATED);
        final VBox root = new VBox(10);
        root.setPadding(new Insets(10));
        StringWriter errorMessage = new StringWriter();
        exception.printStackTrace(new PrintWriter(errorMessage));
        final Label detailsLabel = new Label(errorMessage.toString());
        TitledPane details = new TitledPane();
        details.setText("Details:");
        Label briefMessageLabel = new Label(message);
        final HBox detailsLabelHolder =new HBox();

        Button closeButton = new Button("OK");
        closeButton.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                dialog.hide();
            }
        });
        HBox closeButtonHolder = new HBox();
        closeButtonHolder.getChildren().add(closeButton);
        closeButtonHolder.setAlignment(Pos.CENTER);
        closeButtonHolder.setPadding(new Insets(5));
        root.getChildren().addAll(briefMessageLabel, details, detailsLabelHolder, closeButtonHolder);
        details.setExpanded(false);
        details.setAnimated(false);

        details.expandedProperty().addListener(new ChangeListener<Boolean>() {

            @Override
            public void changed(ObservableValue<? extends Boolean> observable,
                    Boolean oldValue, Boolean newValue) {
                if (newValue) {
                    detailsLabelHolder.getChildren().add(detailsLabel);
                } else {
                    detailsLabelHolder.getChildren().remove(detailsLabel);
                }
                dialog.sizeToScene();
            }

        });
        final Scene scene = new Scene(root);

        dialog.setScene(scene);
        dialog.show();
    }


    /*
     * Struct-like class intended to represent the physical dimensions of a page in pixels
     * (as opposed to the dimensions of the (possibly zoomed) view.
     * Used to compute zoom factors for zoomToFit and zoomToWidth.
     * 
     */

    private class PageDimensions {
        private double width ;
        private double height ;
        PageDimensions(double width, double height) {
            this.width = width ;
            this.height = height ;
        }
        @Override
        public String toString() {
            return String.format("[%.1f, %.1f]", width, height);
        }
    }

}

Pdfviewer.java

package pdfviewer;

import java.io.IOException;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class PdfViewer extends Application {
    @Override
    public void start(Stage primaryStage) throws IOException {
        final Parent parent = FXMLLoader.load(getClass().getResource("PdfViewerTwo.fxml"));

        primaryStage.setScene(new Scene(parent,600, 600));
        primaryStage.show();
    }
    public static void main(String[] args) {

        launch(args);
    }
}

PdfViewerTwo.fxml

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Pagination?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.control.ScrollPane?>
<AnchorPane prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="pdfviewer.Controller">
   <children>
      <BorderPane prefHeight="600.0" prefWidth="600.0" AnchorPane.bottomAnchor="2.0" AnchorPane.leftAnchor="2.0" AnchorPane.rightAnchor="2.0" AnchorPane.topAnchor="2.0">
         <top>
            <AnchorPane prefHeight="40.0" BorderPane.alignment="CENTER">
               <children>
                  <Button mnemonicParsing="false" onAction="#loadFile" text="Ouvrir" AnchorPane.leftAnchor="10.0" AnchorPane.topAnchor="10.0" />
                  <Button layoutX="129.0" layoutY="10.0" mnemonicParsing="false" onAction="#zoomFit" text="Minimiser" AnchorPane.leftAnchor="129.0" AnchorPane.topAnchor="10.0" />
                  <Button layoutX="204.0" layoutY="10.0" mnemonicParsing="false" onAction="#zoomWidth" text="agrandir" />
                  <Button layoutX="328.0" layoutY="10.0" mnemonicParsing="false" onAction="#closeFile" text="X" />
                  <Button layoutX="298.0" layoutY="10.0" mnemonicParsing="false" onAction="#zoomOut" text="-" />
                  <Button layoutX="273.0" layoutY="10.0" mnemonicParsing="false" onAction="#zoomIn" text="+" />
                  <Label fx:id="currentZoomLabel" layoutX="442.0" layoutY="13.0" prefHeight="18.0" prefWidth="51.0" />
                  <Label layoutX="85.0" layoutY="12.0" text="Zoom:">
                     <font>
                        <Font size="14.0" />
                     </font>
                  </Label>
                  <Button fx:id="nextButton" layoutX="402.0" layoutY="10.0" mnemonicParsing="false" onAction="#nextPage" text="=&gt;" />
                  <Button fx:id="previousButton" layoutX="360.0" layoutY="10.0" mnemonicParsing="false" onAction="#previousPage" text="&lt;=" />
               </children>
            </AnchorPane>
         </top>
         <fx:define>
        <ScrollPane fx:id="scroller" pannable="true" />
    </fx:define>
         <center>
            <Pagination fx:id="pagination" BorderPane.alignment="CENTER" />
         </center>
         <left>
            <AnchorPane prefHeight="556.0" prefWidth="28.0" BorderPane.alignment="CENTER">
               <children>
                  <Button layoutY="76.0" mnemonicParsing="false" onAction="#openPdfOne" text="Pdf1" />
               </children>
            </AnchorPane>
         </left>
      </BorderPane>
   </children>
</AnchorPane>

我如何干净地关闭文件？ 

我会非常感激

附加了屏幕截图和代码*

https://www.youtube.com/watch?v=9RhSmKbEUKg

Complete Source Code

最诚挚的问候

我真的很困惑，我在javaFx中有一个pdf查看器应用程序，我的问题是我想创建一个按钮，用closeFile（）方法关闭currentFile。所以我写了currentFile.set（null）...