Since so many people ask for this code, but never get it, I figured I’d repost it. I didn’t write it, but I added the jpeg saving part, and modified it for my device, which you will have to do to get it to work. Just go into JMFRegistry and get the device name from your webcam and then edit the code. Also, keep in mind that some webcams don’t work with JMF. You have to have a webcam that supports VFW or WDM interface.
And here’s the code:

import javax.swing.*;
import javax.swing.event.*;
import java.io.*;
import javax.media.*;
import javax.media.format.*;
import javax.media.util.*;
import javax.media.control.*;
import javax.media.protocol.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import com.sun.image.codec.jpeg.*;
 
public class SwingCapture extends Panel implements ActionListener 
{
  public static Player player = null;
  public CaptureDeviceInfo di = null;
  public MediaLocator ml = null;
  public JButton capture = null;
  public Buffer buf = null;
  public Image img = null;
  public VideoFormat vf = null;
  public BufferToImage btoi = null;
  public ImagePanel imgpanel = null;
  
  public SwingCapture() 
  {
    setLayout(new BorderLayout());
    setSize(320,550);
    
    imgpanel = new ImagePanel();
    capture = new JButton("Capture");
    capture.addActionListener(this);
    
    String str1 = "vfw:Logitech USB Video Camera:0";
    String str2 = "vfw:Microsoft WDM Image Capture (Win32):0";
    di = CaptureDeviceManager.getDevice(str2);
    ml = di.getLocator();
    
    try 
    {
      player = Manager.createRealizedPlayer(ml);
      player.start();
      Component comp;
      
      if ((comp = player.getVisualComponent()) != null)
      {
        add(comp,BorderLayout.NORTH);
      }
      add(capture,BorderLayout.CENTER);
      add(imgpanel,BorderLayout.SOUTH);
    } 
    catch (Exception e) 
    {
      e.printStackTrace();
    }
  }
 
 
  
  public static void main(String[] args) 
  {
    Frame f = new Frame("SwingCapture");
    SwingCapture cf = new SwingCapture();
    
    f.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
      playerclose();
      System.exit(0);}});
    
    f.add("Center",cf);
    f.pack();
    f.setSize(new Dimension(320,550));
    f.setVisible(true);
  }
  
  
  public static void playerclose() 
  {
    player.close();
    player.deallocate();
  }
  
 
  public void actionPerformed(ActionEvent e) 
  {
    JComponent c = (JComponent) e.getSource();
    
    if (c == capture) 
    {
      // Grab a frame
      FrameGrabbingControl fgc = (FrameGrabbingControl)
      player.getControl("javax.media.control.FrameGrabbingControl");
      buf = fgc.grabFrame();
      
      // Convert it to an image
      btoi = new BufferToImage((VideoFormat)buf.getFormat());
      img = btoi.createImage(buf);
      
      // show the image
      imgpanel.setImage(img);
      
      // save image
      saveJPG(img,"c:\\test.jpg");
    }
  }
  
  class ImagePanel extends Panel 
  {
    public Image myimg = null;
    
    public ImagePanel() 
    {
      setLayout(null);
      setSize(320,240);
    }
    
    public void setImage(Image img) 
    {
      this.myimg = img;
      repaint();
    }
    
    public void paint(Graphics g) 
    {
      if (myimg != null) 
      {
        g.drawImage(myimg, 0, 0, this);
      }
    }
  }
  
 
  public static void saveJPG(Image img, String s)
  {
    BufferedImage bi = new BufferedImage(img.getWidth(null), img.getHeight(null), BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = bi.createGraphics();
    g2.drawImage(img, null, null);
 
    FileOutputStream out = null;
    try
    { 
      out = new FileOutputStream(s); 
    }
    catch (java.io.FileNotFoundException io)
    { 
      System.out.println("File Not Found"); 
    }
    
    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
    JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi);
    param.setQuality(0.5f,false);
    encoder.setJPEGEncodeParam(param);
    
    try 
    { 
      encoder.encode(bi); 
      out.close(); 
    }
    catch (java.io.IOException io) 
    {
      System.out.println("IOException"); 
    }
  }
  
}

More detail