用jpcap抓的包，关于以太网的包问题

[anakin_feng]

我用jpcap的方法抓到了包，解析以太网的包，类型为什么会出现负的，mac地址是没问题的

package com.fym.start;

import com.fym.main.MainPacketReceiver;

import jpcap.JpcapCaptor;  
import jpcap.NetworkInterface;  

public class Start {  
    //程序启动主方法  
   public static void main(String args[]){  
	   try {
			// 获取本机上的网络接口对象数组
		   	final NetworkInterface[] devices = JpcapCaptor.getDeviceList();
			for (int i = 0; i < devices.length; i++) {
				NetworkInterface nc = devices[i];
				// 创建某个卡口上的抓取对象,最大为2000个
				JpcapCaptor jpcap = JpcapCaptor.openDevice(nc, 2000, true, 20);
				startCapThread(jpcap);
				System.out.println("开始抓取第" + i + "个卡口上的数据");
			}
        }catch(Exception ef){  
            ef.printStackTrace();  
            System.out.println("启动失败:  "+ef);  
        }  
  
   }  
    //将每个Captor放到独立线程中运行  
   public static void startCapThread(final JpcapCaptor jpcap ){  
       java.lang.Runnable rnner=new Runnable(){  
           public void run(){  
               //使用接包处理器循环抓包  
               jpcap.loopPacket(-1, new MainPacketReceiver());  
           }  
       };  
       new Thread(rnner).start();//启动抓包线程  
   }      
}  
  

package com.fym.main;

import jpcap.PacketReceiver;
import jpcap.packet.Packet;


public class MainPacketReceiver  implements PacketReceiver {  
  /** 
   * 实现的接包方法: 
   */  
	public void receivePacket(Packet packet) { 
		byte b[] = packet.header; 
		
		System.out.print("-------以太网首部信息:-------\r\n");
		int i=0;
		System.out.print("i = "+i+"    ");
		System.out.print("目的Mac地址: "+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+"\r\n");
		System.out.print("i = "+i+"    ");
		System.out.print("源Mac地址: "+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+":"+(b[i++]&0xFF)+"\r\n");
		System.out.print("i = "+i+"    ");
		System.out.println("类型:"+((b[i++]<<8)|(b[i])));

	}  
} 

[anakin_feng]

难道就没人吗