public class checkwangka {

    public static void main(String [] args) throws Exception
    {
        NetworkInterface[] devices = JpcapCaptor.getDeviceList();
        int index = 0;
        if(devices.length>1)/*去掉虚拟网卡的处理*/
          index =  1;
         JpcapCaptor captor = JpcapCaptor.openDevice(devices[index], 65535, false, 20);
         captor.loopPacket(-1, new Receiver());
    }
}
class Receiver implements  PacketReceiver
{   
    /*实例receivePacket方法*/
   public void receivePacket(Packet packet)
   {
      /*进行简单的处理*/
     System.out.println(packet);
   }

}

java.lang.UnsupportedClassVersionError: jpcap/PacketReceiver (Unsupported major.minor version 49.0)
    at java.lang.ClassLoader.defineClass0(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at (Unknown Source)
    at (Unknown Source)
    at (Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at (Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)
Exception in thread "main"