java中得到计算机MAC网卡标识，IP，计算机名称等唯一标识问题

网站中投票器的处理机制

第一，直接用IP判断，这种方式就是一个IP只能投票一定次数，方法可用下面代码中的getIpAddr() 中得到ipAddress的返回值判断即可。

第二，用MAC网卡标识进行判断，一台机器只能投票一定次数，方法可用下面代码中的getMAXAddress.但是此方法在很多网关设置了防火墙的情况下无法得到，而且还会造成异常警告，而且捕捉这个警告的时间还非常长，因此慎用。

第三，用ip地址和计算机名称联合判断，一个网段中计算机名称是不允许重名的，因此可用ip加计算机名称联合判断。方法可用下面代码中的getIpAddr() 的最后返回值即可

/**
* 根据IP地址获取客户端的MAC
* @param ipAddress
* @return
* @throws IOException
*/
public static String getMACAddress(String ipAddress) throws IOException {
System.out.println("客户端的IP地址为："+ipAddress);
String str = "", strMAC = "", macAddress = "";
Process pp = Runtime.getRuntime().exec("nbtstat -a " + ipAddress);
InputStreamReader ir = new InputStreamReader(pp.getInputStream());
LineNumberReader input = new LineNumberReader(ir);
for (int i = 1; i < 100; i++) {
str = input.readLine();
if (str != null) {
if (str.indexOf("MAC Address") > 1) {
strMAC = str.substring(str.indexOf("MAC Address") + 14,str.length());
break;
}
}
}
if (strMAC.length() < 17) {

return "Error!";
}
macAddress = strMAC.substring(0, 2) + ":" + strMAC.substring(3, 5)+ ":" + strMAC.substring(6, 8) + ":" + strMAC.substring(9, 11)+ ":" + strMAC.substring(12, 14) + ":"+ strMAC.substring(15, 17);
System.out.println("客户端的MAC地址为："+macAddress);
return macAddress;
}
/**
* 获取客户端IP地址
* @return
*/
public static String getIpAddr() throws IOException{
HttpServletRequest req=ServletActionContext.getRequest();
String ipAddress = req.getHeader("x-forwarded-for");
if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress))
ipAddress = req.getHeader("Proxy-Client-IP");
if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress))
ipAddress = req.getHeader("WL-Proxy-Client-IP");
if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress))
ipAddress = req.getHeader("HTTP_X_FORWARDED_FOR");
if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress))
ipAddress = req.getHeader("HTTP_CLIENT_IP");
if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress))
ipAddress = req.getRemoteAddr();
String host = req.getRemoteHost();
String ip = ipAddress+":"+host;
System.out.println("访问者IP="+ip);
return ip;
}