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。

 1 import java.io.File;
 2
 3 import javafx.application.Application;
 4 import javafx.event.ActionEvent;
 5 import javafx.event.EventHandler;
 6 import javafx.geometry.Insets;
 7 import javafx.geometry.Pos;
 8 import javafx.scene.Scene;
 9 import javafx.scene.control.Button;
10 import javafx.scene.layout.GridPane;
11 import javafx.stage.FileChooser;
12 import javafx.stage.FileChooser.ExtensionFilter;
13 import javafx.stage.Stage;
14
15 public class Main extends Application {
16
17     public static void main(String[] args) {
18         launch(args);
19     }
20
21     @Override
22     public void start(Stage primaryStage) throws Exception {
23         // Create a pane to hold a button
24         GridPane pane = new GridPane();
25         pane.setStyle("-fx-border-color: green;");
26         pane.setAlignment(Pos.CENTER);
27         pane.setPadding(new Insets(10, 10, 10, 10));
28         pane.setHgap(10);
29         pane.setVgap(10);
30
31         // Create a button to choose a file
32         Button btChooseFile = new Button("Choose File");
33         pane.add(btChooseFile, 0, 0);
34
35         // Set the primary stage properties
36         primaryStage.setScene(new Scene(pane, 400, 200));
37         primaryStage.setTitle("Starting...");
38         primaryStage.setResizable(false);
39         primaryStage.show();
40
41         //
42         btChooseFile.setOnAction(new EventHandler<ActionEvent>() {
43             @Override
44             public void handle(ActionEvent event) {
45                 FileChooser fileChooser = new FileChooser();
46                 fileChooser.setTitle("Choose File");
47                 fileChooser.setInitialDirectory(new File("J:" + File.separator + "PrtSc" + File.separator + "20190321"));
48                 fileChooser.getExtensionFilters().addAll(new ExtensionFilter("Text Files", "*.txt"), new ExtensionFilter("All Files", "*.*"));
49                 File file = fileChooser.showOpenDialog(primaryStage);
50                 if (file != null) {
51                     System.out.println(file.getAbsolutePath());
52                 }
53             }
54         });
55     }
56 }

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，

 1 import java.io.File;
 2 import java.io.FileInputStream;
 3 import java.io.FileNotFoundException;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.InputStream;
 7 import java.io.OutputStream;
 8
 9 import javafx.application.Application;
10 import javafx.event.ActionEvent;
11 import javafx.event.EventHandler;
12 import javafx.geometry.Insets;
13 import javafx.geometry.Pos;
14 import javafx.scene.Scene;
15 import javafx.scene.control.Button;
16 import javafx.scene.layout.GridPane;
17 import javafx.stage.FileChooser;
18 import javafx.stage.FileChooser.ExtensionFilter;
19 import javafx.stage.Stage;
20
21 public class Main extends Application {
22
23     public static void main(String[] args) {
24         launch(args);
25     }
26
27     @Override
28     public void start(Stage primaryStage) throws Exception {
29         // Create a pane to hold a button
30         GridPane pane = new GridPane();
31         pane.setStyle("-fx-border-color: green;");
32         pane.setAlignment(Pos.CENTER);
33         pane.setPadding(new Insets(10, 10, 10, 10));
34         pane.setHgap(10);
35         pane.setVgap(10);
36
37         // Create a button to choose a file
38         Button btChooseFile = new Button("Choose File");
39         pane.add(btChooseFile, 0, 0);
40
41         // Set the primary stage properties
42         primaryStage.setScene(new Scene(pane, 400, 200));
43         primaryStage.setTitle("Starting...");
44         primaryStage.setResizable(false);
45         primaryStage.show();
46
47         //
48         btChooseFile.setOnAction(new EventHandler<ActionEvent>() {
49             @Override
50             public void handle(ActionEvent event) {
51                 FileChooser fileChooser = new FileChooser();
52                 fileChooser.setTitle("Choose File");
53                 fileChooser.getExtensionFilters().addAll(new ExtensionFilter("All Files", "*.*"));
54                 //
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
60                         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
76                     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             }
86         });
87     }
88 }