vlcj视频未显示，但听到了视频声音

Question

when the application is run, the sound is heard and other button controls are visible on the frame, but the panel containing the video does not show any black screen neither is it displayed on the frame.

public class MediaPlayer extends JPanel {

private JFrame ourframe = new JFrame();
//Declares our media player component
private EmbeddedMediaPlayerComponent mediaplayer;
//This string holds the media URL path
private String mediapath = "";
//This string holds the vlc URL path
private final String vlcpath = "C:\\Program Files (x86)\\VideoLAN\\VLC";
private JPanel panel, panel2;
private JButton play_btn, stop_btn, foward_btn, rewind_btn, enlarge_btn;
private JSlider timeline;

public MediaPlayer(String mediapath) {
    this.mediapath = mediapath;
    NativeLibrary.addSearchPath(RuntimeUtil.getLibVlcLibraryName(), vlcpath);
    mediaplayer = new EmbeddedMediaPlayerComponent();

    panel = new JPanel();
    panel.setLayout(new BorderLayout());
    panel.add(mediaplayer, BorderLayout.CENTER); //panel containing the video

    play_btn = new JButton("play");
    stop_btn = new JButton("stop");
    foward_btn = new JButton("ff");
    rewind_btn = new JButton("rew");
    enlarge_btn = new JButton("enlarge");

    timeline = new JSlider(0, 100, 0);
    timeline.setMajorTickSpacing(10);
    timeline.setMajorTickSpacing(5);
    timeline.setPaintTicks(true);

    panel2 = new JPanel();
    panel2.setLayout(new FlowLayout(FlowLayout.CENTER));
    panel2.add(play_btn);
    panel2.add(stop_btn);
    panel2.add(foward_btn);
    panel2.add(rewind_btn);
    panel2.add(enlarge_btn);
    panel2.add(timeline);
    panel.add(panel2, BorderLayout.SOUTH);
    add(panel);
}

public void play() {
    mediaplayer.getMediaPlayer().playMedia(mediapath);
}

public static void main(String[] args) {
    //Declare and initialize local variables
    String mediaPath = "";
    mediaPath = "C:\\Users\\goldAnthony\\Desktop\\Videos\\Whistle.mp4";

    //creates instances of the VlcPlayer object, pass the mediaPath and invokes the method "run"
    MediaPlayer mediaplayer = new MediaPlayer(mediaPath);
    JFrame ourframe = new JFrame();
    ourframe.setContentPane(mediaplayer);
    ourframe.setSize(720, 560);
    ourframe.setVisible(true);
    mediaplayer.play();
    ourframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

}

Answer 1

This is because you are adding the video surface to a JPanel without choosing an appropriate layout manager.

By default JPanel has a FlowLayout and this will layout components according to their preferred size.

The video surface panel has no preferred size set.

The solution is to set a layout manager like BorderLayout on the main panel.

So at the end of your constructor, instead of this...

add(panel);

...do this...

setLayout(new BorderLayout());
add(panel, BorderLayout.CENTER);

Cross-posted at [1].

[1] https://groups.google.com/forum/#!topic/vlcj-users/m0zG-fx4qm8