java - Netbeans Java WebcamCapture が例外をスローする

Question

Netbeans を使用して、ラップトップ カメラまたは別の USB カメラを接続してスクリーンショットを撮ろうとしています。私のプロジェクトには、それを行うための2つのクラスがあります。

1. functiiwebcam.java (デバイスを接続して画像をキャプチャするためのすべての関数が含まれています)

   これはコードです：

   import java.util.logging.Level;
   import java.util.logging.Logger;
   import javax.media.*;
   import javax.media.cdm.CaptureDeviceManager;
   import java.io.*;
   import java.awt.*;
   import javax.media.control.FrameGrabbingControl;
   import javax.media.format.VideoFormat;
   import javax.media.util.BufferToImage;
   import javax.swing.JLabel;
   import javax.swing.JOptionPane;
   
   public class functiiwebcam {
       //pentru fereastra, implicit dispozitiv   
       String camera = "vfw:Microsoft WDM Image Capture (Win32):0";
       Player broadcast = null;
   
       public Component Componente() {
           Component componente_video;
   
           try {
               // Selectare dispozitiv
               CaptureDeviceInfo device = CaptureDeviceManager.getDevice(camera);
               //Sursa imaginilor capturate
               MediaLocator localizador = device.getLocator();
               //Locatia este de tipul "vfw://0" video para windows
               //Fereastra pentru afisarea imaginilor in aplicatie
               broadcast = Manager.createRealizedPlayer(localizador);
               //broadcast.start();
           } catch (IOException ex) {
              // Logger.getLogger(functiiwebcam.class.getName()).log(Level.SEVERE, null, ex);
               ex.printStackTrace();
           } catch (NoPlayerException ex) {
               Logger.getLogger(functiiwebcam.class.getName()).log(Level.SEVERE, null, ex);
           } catch (CannotRealizeException ex) {
               Logger.getLogger(functiiwebcam.class.getName()).log(Level.SEVERE, null, ex);
           }
   
           // Obtinerea imaginilor in player
           if ((componente_video = broadcast.getVisualComponent()) != null) {
               //dimensiunea ferestrei de broadcast
               componente_video.setSize(320, 240);
               return componente_video;
           } else {
   
               return null;
           }
       }
   
       // Metoda pentru captura imaginii
       Image img = null;
       public void capturareImagine() {
           FrameGrabbingControl ControlFG = (FrameGrabbingControl) broadcast.getControl("javax.media.control.FrameGrabbingControl");
           Buffer buffer = ControlFG.grabFrame();
           // creare image awt
           BufferToImage image = new BufferToImage((VideoFormat)buffer.getFormat());
           img = image.createImage(buffer);
       }
   
       public Image getImage() {
           return img;
       }
   
       public void setImage(JLabel lb) {
           capturareImagine();        
           lb.setIcon( new javax.swing.ImageIcon( img ) );
           System.out.println("ancho= " + img.getWidth(null));
           System.out.println("alto= " + img.getHeight(null));
       }
   }
   

2. Webcam.java (デザイン SWING GUI -JFRAME FORM : ボタンとパネルなどを含む)

   ここでは、コード全体は必要ないと思います。インターフェイスを設計したときに Netbeans によって生成されます。クラスだけを入れます：

   import javax.swing.Icon;
   import javax.swing.ImageIcon;
   import javax.swing.JOptionPane;
   
   public class Webcam extends javax.swing.JFrame {
       functiiwebcam b = new functiiwebcam();
       /** Creates new form Webcam */
       public Webcam() {
           initComponents();
           this.setTitle("Webcam");
           // Centreaza ferestra
           this.setLocationRelativeTo(null);
           // Aplicare Layout de tip BOX panoului cu numele broadcast (cel in care se afiseaza imaginile de pe webcam)       
           broadcast.setLayout(new javax.swing.BoxLayout(broadcast, javax.swing.BoxLayout.LINE_AXIS));
           // Adaugarea componentei video
           broadcast.add(b.Componente());
       }
   
       // Button for webcam capture
       private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
           b.capturareImagine();
   
           Icon icon = new javax.swing.ImageIcon(b.getImage());
           captura.setIcon(icon);
   

アプリケーションを実行すると、この例外がスローされます。しかし、時々それが機能するのは興味深いことです。表示されるウィンドウからデバイスを選択でき、Web カメラからの画像を表示したり、キャプチャしたりすることもできます。なにが問題ですか？

java.io.IOException: Could not connect to capture device
java.io.IOException: Could not connect to capture device
Iun 05, 2012 1:48:54 PM functiiwebcam Componente
SEVERE: null
javax.media.NoPlayerException: Error instantiating class: com.sun.media.protocol.vfw.DataSource : java.io.IOException: Could not connect to capture device
    at javax.media.Manager.createPlayerForContent(Manager.java:1362)
    at javax.media.Manager.createPlayer(Manager.java:417)
    at javax.media.Manager.createRealizedPlayer(Manager.java:553)
    at functiiwebcam.Componente(functiiwebcam.java:37)
    at Webcam.<init>(Webcam.java:30)
    at MediaPlayer.jMenuItem1ActionPerformed(MediaPlayer.java:476)
    at MediaPlayer.access$900(MediaPlayer.java:17)
    at MediaPlayer$11.actionPerformed(MediaPlayer.java:325)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at functiiwebcam.Componente(functiiwebcam.java:48)
    at Webcam.<init>(Webcam.java:30)
    at MediaPlayer.jMenuItem1ActionPerformed(MediaPlayer.java:476)
    at MediaPlayer.access$900(MediaPlayer.java:17)
    at MediaPlayer$11.actionPerformed(MediaPlayer.java:325)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)