java完整版本获取客户端有效IP

//各种奇葩问题如下，考虑IPv4与IPv6
public static String getIpAddr(HttpServletRequest request) throws UnknownHostException {  
        String ip = request.getHeader("X-Forwarded-For");  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("Proxy-Client-IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("WL-Proxy-Client-IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_CLIENT_IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getRemoteAddr();  
        }  
        if(ip != null && ip.equalsIgnoreCase("0:0:0:0:0:0:0:1"))    
        {  
          ip =InetAddress.getLocalHost().getHostAddress().toString();  
        }  
	if (ip == null || ip.length() == 0 || "X-Real-IP".equalsIgnoreCase(ip)) {  
		ip = request.getHeader("X-Real-IP");  
	}
        return ip;  
    }