vlcj - 影片事件載入錯誤

讓我們進一步增強應用程式的功能，其中我們將更新 vlcj - 已完成影片事件 章節並使其具有錯誤處理能力。

處理錯誤事件

使用以下語法（模板方法）新增錯誤事件處理程式：−

mediaPlayerComponent = new EmbeddedMediaPlayerComponent() {
   @Override
   public void error(MediaPlayer mediaPlayer) {
   }
};

或者，我們可以使用以下語法（偵聽器方法）新增錯誤事件處理程式：−

mediaPlayerComponent.getMediaPlayer().addMediaPlayerEventListener(new MediaPlayerEventAdapter() {
   @Override
   public void error(MediaPlayer mediaPlayer) {
   }
});

如果影片載入失敗，則會引發錯誤事件。但由於播放方法立即返回，而錯誤事件（如果影片已載入但無法執行）將在稍後引發。因此，我們必須以非同步方式處理錯誤事件。

示例

在 Eclipse 中開啟專案 mediaPlayer，該專案是在 環境設定 章節中建立的。

使用以下程式碼更新 App.java：−

App.java

package com.tutorialspoint.media;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import uk.co.caprica.vlcj.player.base.MediaPlayer;
import uk.co.caprica.vlcj.player.component.EmbeddedMediaPlayerComponent;

public class App extends JFrame {
   private static final long serialVersionUID = 1L;
   private static final String TITLE = "My First Media Player";
   private static final String VIDEO_PATH = "D:\\Downloads\\sunset-beach.mp4";
   private final EmbeddedMediaPlayerComponent mediaPlayerComponent;
   private JButton playButton;
   private JButton pauseButton;
   private JButton rewindButton;
   private JButton skipButton;

   public App(String title) {
      super(title);
      mediaPlayerComponent = new EmbeddedMediaPlayerComponent() {
         @Override
         public void playing(MediaPlayer mediaPlayer) {
            super.playing(mediaPlayer);
            System.out.println("Media Playback started.");
         }
         @Override
         public void finished(MediaPlayer mediaPlayer) {
            super.playing(mediaPlayer);
            System.out.println("Media Playback finished.");
         }
         @Override
         public void error(MediaPlayer mediaPlayer) {
            SwingUtilities.invokeLater(new Runnable() {        		
               public void run() {
	              System.out.println("Failed to load Media.");
               }        	       
            });
         }
      };		
   }
   public void initialize() {
      this.setBounds(100, 100, 600, 400);
      this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      this.addWindowListener(new WindowAdapter() {
         @Override
         public void windowClosing(WindowEvent e) {
            mediaPlayerComponent.release();
            System.exit(0);
         }
      });    	
      JPanel contentPane = new JPanel();
      contentPane.setLayout(new BorderLayout());   	 
      contentPane.add(mediaPlayerComponent, BorderLayout.CENTER);
      JPanel controlsPane = new JPanel();
      playButton = new JButton("Play");
      controlsPane.add(playButton);    
      pauseButton = new JButton("Pause");
      controlsPane.add(pauseButton);
      rewindButton = new JButton("Rewind");
      controlsPane.add(rewindButton);
      skipButton = new JButton("Skip");
      controlsPane.add(skipButton);
      contentPane.add(controlsPane, BorderLayout.SOUTH);

      playButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            mediaPlayerComponent.mediaPlayer().controls().play();
         }
      });  
      pauseButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            mediaPlayerComponent.mediaPlayer().controls().pause();
         }
      });
      rewindButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            mediaPlayerComponent.mediaPlayer().controls().skipTime(-14000);
         }
      });
      skipButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            mediaPlayerComponent.mediaPlayer().controls().skipTime(4000);
         }
      });
      this.setContentPane(contentPane);
      this.setVisible(true);
   }
   public void loadVideo(String path) {
      mediaPlayerComponent.mediaPlayer().media().startPaused(path);   	
   }
   public static void main( String[] args ){
      try {            
         UIManager.setLookAndFeel(
         UIManager.getSystemLookAndFeelClassName());
      } 
      catch (Exception e) {
         System.out.println(e);
      }
      App application = new App(TITLE);
      application.initialize(); 
      application.setVisible(true);  
      application.loadVideo(VIDEO_PATH);
   }
}

此示例中提供了指向媒體檔案的無效路徑。透過右鍵單擊檔案並選擇“作為 Java 應用程式執行”來執行應用程式。成功啟動後，如果一切正常，則應顯示以下結果：−

現在，您將在控制檯中看到如下訊息：−

Failed to load Media.