JavaFX FileChooser文件选择器，缓存上一次打开的目录

例1：点击按钮Choose File打开文件选择器，并打开指定的目录。这是通过final void setInitialDirectory(final File value)方法实现的。

import java.io.File;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.stage.FileChooser;
import javafx.stage.FileChooser.ExtensionFilter;
import javafx.stage.Stage;

public class Main extends Application {

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) throws Exception {
        // Create a pane to hold a button
        GridPane pane = new GridPane();
        pane.setStyle("-fx-border-color: green;");
        pane.setAlignment(Pos.CENTER);
        pane.setPadding(new Insets(10, 10, 10, 10));
        pane.setHgap(10);
        pane.setVgap(10);
        
        // Create a button to choose a file
        Button btChooseFile = new Button("Choose File");
        pane.add(btChooseFile, 0, 0);
                
        // Set the primary stage properties
        primaryStage.setScene(new Scene(pane, 400, 200));
        primaryStage.setTitle("Starting...");
        primaryStage.setResizable(false);
        primaryStage.show();
        
        // 
        btChooseFile.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                FileChooser fileChooser = new FileChooser();
                fileChooser.setTitle("Choose File");
                fileChooser.setInitialDirectory(new File("J:" + File.separator + "PrtSc" + File.separator + "20190321"));
                fileChooser.getExtensionFilters().addAll(new ExtensionFilter("Text Files", "*.txt"), new ExtensionFilter("All Files", "*.*"));
                File file = fileChooser.showOpenDialog(primaryStage);
                if (file != null) {
                    System.out.println(file.getAbsolutePath());
                }
            }
        });
    }
}

UI：

例2：增加一个缓存文件，用于记录上一次选中的目录。

工程结构：

第62行的代码，涉及到的知识点：Java - byte[] 和 String互相转换，

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.stage.FileChooser;
import javafx.stage.FileChooser.ExtensionFilter;
import javafx.stage.Stage;

public class Main extends Application {

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) throws Exception {
        // Create a pane to hold a button
        GridPane pane = new GridPane();
        pane.setStyle("-fx-border-color: green;");
        pane.setAlignment(Pos.CENTER);
        pane.setPadding(new Insets(10, 10, 10, 10));
        pane.setHgap(10);
        pane.setVgap(10);
        
        // Create a button to choose a file
        Button btChooseFile = new Button("Choose File");
        pane.add(btChooseFile, 0, 0);
                
        // Set the primary stage properties
        primaryStage.setScene(new Scene(pane, 400, 200));
        primaryStage.setTitle("Starting...");
        primaryStage.setResizable(false);
        primaryStage.show();
        
        // 
        btChooseFile.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                FileChooser fileChooser = new FileChooser();
                fileChooser.setTitle("Choose File");
                fileChooser.getExtensionFilters().addAll(new ExtensionFilter("All Files", "*.*"));
                //
                File cacheFile = new File("cache.txt");
                if (cacheFile.exists()) {
                    try (InputStream inputStream = new FileInputStream(cacheFile)) {
                        byte[] bytes = new byte[(int) cacheFile.length()];
                        // Read the contents of the cache.txt
                        inputStream.read(bytes);
                        //
                        File directory = new File(new String(bytes));
                        if (directory.exists()) {
                            fileChooser.setInitialDirectory(directory);
                        }
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
                }
                //
                File file = fileChooser.showOpenDialog(primaryStage);
                if (file != null) {
                    // Store the directory to the cache.txt
                    try (OutputStream outputStream = new FileOutputStream(cacheFile)) {
                        byte[] bytes = file.getParent().getBytes();
                        outputStream.write(bytes);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }
}