JavaFX 指定路径的球

 package FXExample;

 import javafx.animation.PathTransition;
 import javafx.animation.PathTransitionBuilder;
 import javafx.application.Application;
 import javafx.event.ActionEvent;
 import javafx.event.EventHandler;
 import javafx.geometry.Point2D;
 import javafx.scene.Group;
 import javafx.scene.Scene;
 import javafx.scene.SceneBuilder;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.paint.Color;
 import javafx.scene.paint.CycleMethod;
 import javafx.scene.paint.RadialGradient;
 import javafx.scene.paint.Stop;
 import javafx.scene.shape.Circle;
 import javafx.scene.shape.CircleBuilder;
 import javafx.scene.shape.LineTo;
 import javafx.scene.shape.MoveTo;
 import javafx.scene.shape.Path;
 import javafx.stage.Stage;
 import javafx.util.Duration;


 public class WorkingWithTheSceneGraph extends Application{

     Path onePath = new Path();
     Point2D anchorPt;//anchor:锚
     public static void main(String[] args) {
         launch(args);
     }

     @Override
     public void start(Stage primaryStage) throws Exception {
         primaryStage.setTitle("Chapter 2-3 Working with the Scene Graph");
         final Group root = new Group();
         root.getChildren().add(onePath);

         final Scene scene = SceneBuilder.create()
                 .root(root)
                 .width(300)
                 .height(300)
                 .fill(Color.PINK)
                 .build();
         RadialGradient gradient1 = new RadialGradient(0,.1,100,100,20,false,CycleMethod.NO_CYCLE,
                 new Stop(0,Color.RED),new Stop(1,Color.BLACK));

         //sphere:n. 范围；球体
         final Circle sphere = CircleBuilder.create()
                 .centerX(100).centerY(100).radius(20).fill(gradient1).build();
         root.getChildren().add(sphere);

         // animate sphere by following the path.通过下面的路径动画
         final PathTransition pathTransition = PathTransitionBuilder.create()
                 .duration(Duration.millis(4000))//持续时间
                 .cycleCount(1)//循环周期
                 .node(sphere)//形状
                 .path(onePath)//路径
                 .orientation(PathTransition.OrientationType.ORTHOGONAL_TO_TANGENT)//方向
                 .build();

         // once finished clear path.结束后清除路径
         pathTransition.onFinishedProperty().set(new EventHandler(){

             @Override
             public void handle(ActionEvent event) {
                 onePath.getElements().clear();

             }});

         // starting initial path:初始路径
         scene.onMousePressedProperty().set(new EventHandler(){

             @Override
             public void handle(MouseEvent event) {
                 onePath.getElements().clear();
                 anchorPt = new Point2D(event.getX(),event.getY());
                 onePath.setStroke(Color.BLACK);
                 onePath.setStrokeWidth(3);
                 onePath.getElements().add(new MoveTo(anchorPt.getX(),anchorPt.getY()));

             }});
         // dragging creates lineTos added to the path拖动创建lineTos添加到路径
         scene.onMouseDraggedProperty().set(new EventHandler(){

             @Override
             public void handle(MouseEvent event) {
                 onePath.getElements().add(new LineTo(event.getX(),event.getY()));
             }});
         scene.onMouseReleasedProperty().set(new EventHandler(){

             @Override
             public void handle(MouseEvent event) {
                 onePath.setStrokeWidth(10);
                 if(onePath.getElements().size() > 1){
                     pathTransition.stop();
                     pathTransition.playFromStart();
                 }

             }});

         primaryStage.setScene(scene);
         primaryStage.show();
     }

 }