在JavaFx上编写的MediaPlayer不起作用

Question

我只重写了视频https://www.youtube.com/watch?v=bWl98dhvf8Q（到7.51）的代码。但是我使用Eclipse（那个人使用IntelliJ IDEA），我在目录/ home / lynda / workspace / Lab11 /的视频，它包含Focus.mp4，它是电影的预告片（2:24）。

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;
import javafx.scene.media.MediaView;
import javafx.scene.paint.Color;

public class Player extends Application{

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

    @Override
    public void start(Stage stage) throws Exception {
        Group root = new Group();

        Media md = new Media("file:///home/lynda/workspace/Lab11/Focus.mp4");
        MediaPlayer plr = new MediaPlayer(md);
        MediaView view = new MediaView(plr);

        root.getChildren().add(view);
        Scene scn = new Scene(root, 400, 400, Color.BLACK);
        stage.setScene(scn);
        stage.show();

        plr.play();
    }

}

我有很多这样的问题：

 Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(LauncherImpl.java:182)
    at com.sun.javafx.application.LauncherImpl$$Lambda$55/29803442.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: MediaException: UNKNOWN : com.sun.media.jfxmedia.MediaException: Could not create player! : com.sun.media.jfxmedia.MediaException: Could not create player!
    at javafx.scene.media.MediaException.exceptionToMediaException(MediaException.java:146)
    at javafx.scene.media.MediaPlayer.init(MediaPlayer.java:511)
    at javafx.scene.media.MediaPlayer.<init>(MediaPlayer.java:414)
    at Player.start(Player.java:23)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
    at com.sun.javafx.application.LauncherImpl$$Lambda$58/4696732.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl$$Lambda$50/32203826.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
    at com.sun.javafx.application.PlatformImpl$$Lambda$53/23680289.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
    at com.sun.javafx.application.PlatformImpl$$Lambda$51/21992497.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
    at com.sun.glass.ui.gtk.GtkApplication$$Lambda$41/22543536.run(Unknown Source)
    ... 1 more
Caused by: com.sun.media.jfxmedia.MediaException: Could not create player!
    at com.sun.media.jfxmediaimpl.NativeMediaManager.getPlayer(NativeMediaManager.java:224)
    at com.sun.media.jfxmedia.MediaManager.getPlayer(MediaManager.java:104)
    at javafx.scene.media.MediaPlayer.init(MediaPlayer.java:467)
    ... 16 more
Exception running application Player

抱歉我的英语。