JavaFX -多个按钮拖放文本的TextArea

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextArea;
import javafx.scene.input.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class DragAndDropExample extends Application {

    @Override
    public void start(Stage primaryStage) {
        Button button1 = new Button("Button 1");
        Button button2 = new Button("Button 2");
        TextArea textArea = new TextArea();

        button1.setOnDragDetected(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent event) {
                Dragboard db = button1.startDragAndDrop(TransferMode.COPY);
                ClipboardContent content = new ClipboardContent();
                content.putString(button1.getText());
                db.setContent(content);
                event.consume();
            }
        });

        textArea.setOnDragOver(new EventHandler<DragEvent>() {
            public void handle(DragEvent event) {
                if (event.getGestureSource() != textArea && event.getDragboard().hasString()) {
                    event.acceptTransferModes(TransferMode.COPY);
                }
                event.consume();
            }
        });

        textArea.setOnDragDropped(new EventHandler<DragEvent>() {
            public void handle(DragEvent event) {
                Dragboard db = event.getDragboard();
                boolean success = false;
                if (db.hasString()) {
                    textArea.appendText(db.getString() + "\n");
                    success = true;
                }
                event.setDropCompleted(success);
                event.consume();
            }
        });

        VBox vbox = new VBox(button1, button2, textArea);
        Scene scene = new Scene(vbox, 300, 200);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}