请给我编写一段程序，使用JavaFX利用对象和类，实现电视播放功能，至少有5个频道，电视没有打开的时候是黑屏显示。

以下是一个简单的JavaFX电视播放程序，实现了5个频道：

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.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class TVPlayer extends Application {
    private static final int WIDTH = 800;
    private static final int HEIGHT = 600;

    private Television television;

    @Override
    public void start(Stage primaryStage) throws Exception {
        // 创建电视对象，初始频道为0
        television = new Television();

        // 创建播放区域，初始为黑屏
        Rectangle screen = new Rectangle(WIDTH, HEIGHT, Color.BLACK);
        StackPane screenPane = new StackPane(screen);

        // 创建频道选择按钮
        Button btnCh1 = new Button("频道1");
        btnCh1.setOnAction(e -> television.setChannel(1));
        Button btnCh2 = new Button("频道2");
        btnCh2.setOnAction(e -> television.setChannel(2));
        Button btnCh3 = new Button("频道3");
        btnCh3.setOnAction(e -> television.setChannel(3));
        Button btnCh4 = new Button("频道4");
        btnCh4.setOnAction(e -> television.setChannel(4));
        Button btnCh5 = new Button("频道5");
        btnCh5.setOnAction(e -> television.setChannel(5));
        HBox channelBox = new HBox(btnCh1, btnCh2, btnCh3, btnCh4, btnCh5);
        channelBox.setAlignment(Pos.CENTER);
        channelBox.setSpacing(10);

        // 创建主布局
        BorderPane root = new BorderPane();
        root.setCenter(screenPane);
        root.setBottom(channelBox);

        // 监听频道变化，更新播放区域
        television.addListener((observable, oldValue, newValue) -> {
            screen.setFill(newValue.getColor());
        });

        // 显示窗口
        Scene scene = new Scene(root, WIDTH, HEIGHT);
        primaryStage.setScene(scene);
        primaryStage.setTitle("电视播放器");
        primaryStage.show();
    }

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

class Television {
    private int channel;
    private Channel[] channels;
    private Channel currentChannel;
    private Listener listener;

    public Television() {
        channel = 0;
        channels = new Channel[]{
                new Channel(Color.RED),
                new Channel(Color.GREEN),
                new Channel(Color.BLUE),
                new Channel(Color.YELLOW),
                new Channel(Color.PURPLE)
        };
        currentChannel = channels[channel];
    }

    public void setChannel(int channel) {
        this.channel = channel - 1;
        currentChannel = channels[channel - 1];
        if (listener != null) {
            listener.onChange(currentChannel);
        }
    }

    public void addListener(Listener listener) {
        this.listener = listener;
    }

    interface Listener {
        void onChange(Channel channel);
    }
}

class Channel {
    private Color color;

    public Channel(Color color) {
        this.color = color;
    }

    public Color getColor() {
        return color;
    }
}

该程序使用了JavaFX的布局和控件来实现界面，使用了对象和类来表示电视和频道，使用了接口和回调函数来实现频道变化时的更新。程序启动后，可以通过按钮选择不同的频道，播放区域会相应地更新。如果电视没有打开，播放区域会显示黑屏。