获得真实IP地址

/**
	 * 获得真实IP地址
	 * @param request
	 * @return
	 */
	public static String getIpAddr(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();
		 }
		 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");
		 }
		 // 如果是多级代理，那么取第一个ip为客户ip
		 if (ip != null && ip.indexOf(",") != -1) {
		  ip = ip.substring(ip.lastIndexOf(",") + 1, ip.length()).trim();
		 }
		 return ip;
	}