JavaFX FileChooser文件選擇器，緩存上一次打開的目錄

例1：點擊按鈕Choose File打開文件選擇器，並打開指定的目錄。這是通過final void setInitialDirectory(final File value)方法實現的。

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")); 48                 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：增加一個緩存文件，用於記錄上一次選中的目錄。

工程結構：

第62行的代碼，涉及到的知識點：Java - byte[] 和 String互相轉換，

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", "*.*"));
                // 55                 File cacheFile = new File("cache.txt"); 56                 if (cacheFile.exists()) { 57                     try (InputStream inputStream = new FileInputStream(cacheFile)) { 58                         byte[] bytes = new byte[(int) cacheFile.length()]; 59                         // Read the contents of the cache.txt
 inputStream.read(bytes); 61                         // 62                         File directory = new File(new String(bytes)); 63                         if (directory.exists()) { 64  fileChooser.setInitialDirectory(directory); 65  } 66                     } catch (FileNotFoundException e) { 67  e.printStackTrace(); 68                     } catch (IOException e1) { 69  e1.printStackTrace(); 70  } 71  } 72                 // 73                 File file = fileChooser.showOpenDialog(primaryStage); 74                 if (file != null) { 75                     // Store the directory to the cache.txt
                    try (OutputStream outputStream = new FileOutputStream(cacheFile)) { 77                         byte[] bytes = file.getParent().getBytes(); 78  outputStream.write(bytes); 79                     } catch (FileNotFoundException e) { 80  e.printStackTrace(); 81                     } catch (IOException e) { 82  e.printStackTrace(); 83  } 84  } 85             }
        });
    }
}