獲取客戶端IP x-forwarded-for

	public static String getIpAddrByRequest(HttpServletRequest request) {
		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.getRemoteAddr();
		}
		return ip;
	}

在apache+WebLogic整合系統中，
apache會對request對象進行再包裝，附加一些WLS要用的頭信息。這種情況下，直接用request.getRemoteAddr()是無法取到真正的客戶IP的。apache會增加下列頭信息：X-Forwarded-For=211.161.1.239WL-Proxy-Client-IP=211.161.1.239