本实例是在实例（十）的基础上给按钮加上了句柄，可以用按钮对实例（十）中的圆进行缩放。

本实例的代码如下：

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
 
public class ControlCircle extends Application {
   private CirclePane circlePane = new CirclePane();
   
   @Override // Override the start method in the Application class
       public void start(Stage primaryStage) {
           HBox hBox = new HBox();
           hBox.setSpacing(10);
           hBox.setAlignment(Pos.CENTER);
           Button btEnlarge = new Button("Enlarge");
           Button btShrink = new Button("Shrink");
           hBox.getChildren().add(btEnlarge);
           hBox.getChildren().add(btShrink);
 
           btEnlarge.setOnAction(new EnlargeHandler());
           btShrink.setOnAction(new ShrinkHandler());
       
           BorderPane borderPane = new BorderPane();
           borderPane.setCenter(circlePane);
           borderPane.setBottom(hBox);
           BorderPane.setAlignment(hBox, Pos.CENTER);
 
           Scene scene = new Scene(borderPane, 200, 150);
           primaryStage.setTitle("ControlCircle");
           primaryStage.setScene(scene);
           primaryStage.show();
        }
 
        class EnlargeHandler implements EventHandler<ActionEvent> {
           public void handle(ActionEvent e) {
               circlePane.enlarge();
           }
         }
 
         class ShrinkHandler implements EventHandler<ActionEvent> {
            public void handle(ActionEvent e) {
                circlePane.shrink();
            }
          }
     }
 
     class CirclePane extends StackPane {
        private Circle circle = new Circle(50);
                
        public CirclePane()  {
            getChildren().add(circle);
            circle.setStroke(Color.BLACK);
            circle.setFill(Color.WHITE);
        }
 
        public void enlarge() {
            circle.setRadius(circle.getRadius() +2);
        }
  
        public void shrink() {
             circle.setRadius(circle.getRadius() >2? circle.getRadius() - 2 : circle.getRadius());
        }
    }

本文出自 “冯斌的技术博客” 博客，请务必保留此出处http://fengbin8606.blog.51cto.com/8840305/1575044

冯斌：JavaFx实例（十一）“ControlCircle”