Add basic console input parsing to open files

Author: eschmar

build.gradle

@@ -12,4 +12,4 @@ javafx {
     modules = [ 'javafx.controls' ]
 }
 
-mainClassName = 'HelloFX'
+mainClassName = 'App'

src/main/java/App.java

@@ -0,0 +1,53 @@
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.control.Label;
+import javafx.scene.layout.StackPane;
+import javafx.scene.layout.VBox;
+import javafx.stage.Stage;
+
+import java.awt.*;
+import java.io.File;
+
+public class App extends Application {
+
+    /**
+     * Attempt listening for APP_OPEN_FILE events as soon as possible.
+     */
+    static {
+        if (Desktop.isDesktopSupported() && Desktop.getDesktop().isSupported(Desktop.Action.APP_OPEN_FILE)) {
+            Desktop.getDesktop().setOpenFileHandler(event -> {
+                for (File file : event.getFiles()) {
+                    Operator.parseInput(file.getAbsolutePath());
+                }
+            });
+        }
+    }
+
+    @Override
+    public void start(Stage stage) {
+        // Check for files in provided console parameters
+        Parameters params = getParameters();
+        for (String param : params.getUnnamed()) Operator.parseInput(param);
+        for (String param : params.getRaw()) Operator.parseInput(param);
+
+        if (Operator.getOpenFile() == null && !Operator.chooseNewFile()) {
+            // Failed...
+            return;
+        }
+
+        String javaVersion = System.getProperty("java.version");
+        String javafxVersion = System.getProperty("javafx.version");
+        Label l = new Label("Hello, JavaFX " + javafxVersion + ", running on Java " + javaVersion + ".");
+        // TODO: Show which file was opened.
+
+        String chosenFile = "Opened file: " + Operator.getOpenFile().getAbsolutePath();
+
+        Scene scene = new Scene(new VBox(l, new Label(chosenFile)), 320, 240);
+        stage.setScene(scene);
+        stage.show();
+    }
+
+    public static void main(String[] args) {
+        launch();
+    }
+}

src/main/java/HelloFX.java

@@ -0,0 +1,77 @@
+import javafx.stage.FileChooser;
+
+import java.io.File;
+
+public class Operator {
+    public static final String[] EXTENSIONS = new String[] {"pew"};
+    public static final String DEFAULT_EXTENSION = EXTENSIONS[0];
+    public static final String[] MIME_TYPES = new String[] {"public.data, com.example.pew"};
+    public static final String DEFAULT_FOLDER = "/Users/Shared";
+
+    private static File openFile = null;
+
+    private Operator() {}
+
+    public static File getOpenFile() {
+        return openFile;
+    }
+
+    /**
+     * Checks whether an input parameter is a path to a valid file.
+     *
+     * @param input Console input parameter.
+     * @return True if input was path to a valid file.
+     */
+    public static boolean parseInput(String input) {
+        File file = new File(input);
+
+        if (!file.exists() || file.isDirectory()) {
+            return false;
+        }
+
+        boolean validExtension = false;
+        for (String ext : EXTENSIONS) {
+            if (!file.getName().endsWith(ext)) continue;
+            validExtension = true;
+            break;
+        }
+
+        if (!validExtension) return false;
+
+        openFile = file;
+        return true;
+    }
+
+    /**
+     * Prompts the user to choose a file from storage.
+     *
+     * @return True if successfully found a file.
+     */
+    public static boolean chooseNewFile() {
+        FileChooser fileChooser = new FileChooser();
+
+        // Start from existing directory
+        if (getOpenFile() != null) {
+            fileChooser.setInitialDirectory(openFile.getParentFile());
+        } else {
+            File dir = new File(DEFAULT_FOLDER);
+            if (dir.exists() && dir.isDirectory()) {
+                fileChooser.setInitialDirectory(dir);
+            }
+        }
+
+        // Set extension filter
+        for (String extension : EXTENSIONS) {
+            fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter(
+                    extension + " files", "*." + extension
+            ));
+        }
+
+        // Show open file dialog
+        File candidateFile = fileChooser.showOpenDialog(null);
+        if (candidateFile == null) return false;
+
+        // Parse chosen file
+        return parseInput(candidateFile.getAbsolutePath());
+    }
+}