[转]Java web 开发 获取用户ip

如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，那么真正的用户端的真实IP则是取X-Forwarded-For中第一个非unknown的有效IP字符串。

public String getClientIpAddr(Request 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.getRemoteAddress();
        }
        return ip;
    }