多层集群服务中获取客户端IP地址

在服务端java代码中获取客户端访问IP地址代码：

public String getRequestIp(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.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();
	}
	return ip;
}