**16.19（控制一组风扇）

  编写一个程序，在一组中显示三个风扇，有控制按钮来启动和停止整组风扇，如图16-44所示。

习题分析

• 要完成这道题目，需要将16.18中的代码变成一个自定义面板(继承自BorderPane)，再由第二个类去示例化三个风扇面板

代码示例

编程练习题16_19FanPane.java

package chapter_16;

import javafx.animation.KeyFrame;
import javafx.animation.RotateTransition;
import javafx.animation.Timeline;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Slider;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Circle;
import javafx.util.Duration;

public class 编程练习题16_19FanPane extends BorderPane{
	private Timeline fanAnimation;
	private Arc arc1;
	private Arc arc2;
	private Arc arc3;
	private Arc arc4;
	private double x = 0;
	private double y = 0;
	private double angle = 30;
	private boolean direction = false;
	编程练习题16_19FanPane(){
		drawFan();
	}
	编程练习题16_19FanPane(double x, double y){
		setX(x);
		setY(y);
		drawFan();
	}
	public double getX() {
		return x;
	}
	public void setX(double x) {
		this.x = x;
	}
	public double getY() {
		return y;
	}
	public void setY(double y) {
		this.y = y;
	}
	public void pause() {
		fanAnimation.pause();
	}
	public void play() {
		fanAnimation.play();
	}
	public void reverse() {
		fanAnimation.setRate(fanAnimation.getRate() * -1);// 通过将动画的速率乘以-1，可以实现反转动画的效果。
		direction = !direction;
	}
	
	public void drawFan() {
		setLayoutX(636);
		setLayoutY(637);
		Pane pane = new Pane();
		Circle c = new Circle(x, y, 80);
		c.setStroke(Color.BLACK);
		c.setFill(Color.WHITE);
		pane.getChildren().add(c);
		
		int angle = 30;
			arc1 = new Arc(x, y, 70, 70, angle, 30);
			angle += 90;
			arc1.setFill(Color.BLUE);
			arc1.setType(ArcType.ROUND);
			arc2 = new Arc(x, y, 70, 70, angle, 30);
			angle += 90;
			arc2.setFill(Color.BLUE);
			arc2.setType(ArcType.ROUND);
			arc3 = new Arc(x, y, 70, 70, angle, 30);
			angle += 90;
			arc3.setFill(Color.BLUE);
			arc3.setType(ArcType.ROUND);
			arc4 = new Arc(x, y, 70, 70, angle, 30);
			angle += 90;
			arc4.setFill(Color.BLUE);
			arc4.setType(ArcType.ROUND);
			pane.getChildren().addAll(arc1,arc2,arc3, arc4);
		
		HBox hBox = new HBox();
		hBox.setAlignment(Pos.CENTER);
		hBox.setSpacing(5);
		Button btPause = new Button("Pause");
		Button btResume = new Button("Resume");
		Button btReverse = new Button("Reverse");
		hBox.getChildren().addAll(btPause, btResume, btReverse);
		
		Slider slider = new Slider(1,100,1);
		slider.setPrefWidth(200);
		HBox hBox2 = new HBox(slider);
		hBox2.setAlignment(Pos.CENTER);
		
		EventHandler<ActionEvent> eventHandler = e -> {
            setNewRotate();
        };
        
        fanAnimation = new Timeline();
        //此处设置注意
        fanAnimation.getKeyFrames().add(new KeyFrame(Duration.millis(50), eventHandler));
        fanAnimation.setCycleCount(Timeline.INDEFINITE);
        fanAnimation.play();
		  
		btPause.setOnMouseClicked(e -> pause());
		btResume.setOnMouseClicked(e -> play());
		btReverse.setOnMouseClicked(e -> {
			reverse();
		});
		slider.valueProperty().addListener(ov ->{
			fanAnimation.setRate(slider.getValue());
		});	

		setTop(hBox);
		setCenter(pane);
		setBottom(hBox2);
	}
	 public void setNewRotate()
	    {
	        if (direction)
	        {
	            angle = 10.0;
	        }
	        else
	        	angle = -10.0;

	        arc1.startAngleProperty().setValue((arc1.startAngleProperty().getValue() + angle) % 360);
	        arc2.startAngleProperty().setValue((arc2.startAngleProperty().getValue() + angle) % 360);
	        arc3.startAngleProperty().setValue((arc3.startAngleProperty().getValue() + angle) % 360);
	        arc4.startAngleProperty().setValue((arc4.startAngleProperty().getValue() + angle) % 360);
	    }
}

 编程练习题16_19ControlASetOfFans.java

package chapter_16;

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class 编程练习题16_19ControlASetOfFans extends Application{
	@Override
	public void start(Stage primaryStage) throws Exception {
		HBox hBox = new HBox(10);
		编程练习题16_19FanPane fanPane = new 编程练习题16_19FanPane(100, 100);
		编程练习题16_19FanPane fanPane2 = new 编程练习题16_19FanPane(100, 100);
		编程练习题16_19FanPane fanPane3 = new 编程练习题16_19FanPane(100, 100);
		fanPane.setStyle("-fx-border-color:black");
		fanPane2.setStyle("-fx-border-color:black");
		fanPane3.setStyle("-fx-border-color:black");
		hBox.getChildren().addAll(fanPane,fanPane2,fanPane3);
		
		HBox hBox2 = new HBox(20);
		hBox2.setAlignment(Pos.CENTER);
		Button btStart = new Button("Start All");
		Button btStop = new Button("Stop All");
		hBox2.getChildren().addAll(btStart, btStop);
		
		btStop.setOnMouseClicked(e ->{
			fanPane.pause();
			fanPane2.pause();
			fanPane3.pause();
		});
		btStart.setOnMouseClicked(e ->{
			fanPane.play();
			fanPane2.play();
			fanPane3.play();
		});
		
		BorderPane borderPane = new BorderPane();
		borderPane.setCenter(hBox);
		borderPane.setBottom(hBox2);
		Scene scene = new Scene(borderPane,630, 250);
		primaryStage.setTitle("编程练习题16_19ControlASetOfFans");
		primaryStage.setScene(scene);
		primaryStage.show();
	}
	public static void main(String[] args) {
		Application.launch(args);
	}
}

• 结果展示