使用Netbeans，我正在尝试连接我的笔记本电脑相机或其他USB相机并截取屏幕截图。我的项目中有两个课程：
functiiwebcam.java（它包含连接设备和捕获图像的所有功能）
这是代码：
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));
}
}
Webcam.java（包含设计SWING GUI -JFRAME FORM：按钮和面板等）。
在这里，我认为您不需要整个代码。它是我在设计界面时由Netbeans生成的。我会把这个课程放在一边：
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);
当我运行应用程序时，它会抛出这个异常。但奇怪的是，它有时会起作用;我可以从出现的窗口中选择设备，我可以从网络摄像头看到图像，甚至可以捕获它。有什么问题？
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)