JavaWeb如何尽可能的获取到用户的真实IP

获取用户IP

public static String getIPAddress(HttpServletRequest request) {String ip = null;String ipAddresses = request.getHeader("X-Forwarded-For");if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {ipAddresses = request.getHeader("Proxy-Client-IP");}if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {ipAddresses = request.getHeader("WL-Proxy-Client-IP");}if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {ipAddresses = request.getHeader("HTTP_CLIENT_IP");}if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {ipAddresses = request.getHeader("X-Real-IP");}if (ipAddresses != null && ipAddresses.length() != 0) {ip = ipAddresses.split(",")[0];}if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {ip = request.getRemoteAddr();}return ip;}

当我们通过request获取客户端IP时，自身服务器通常会为了保护信息或者负载均衡的目的，对自身服务器做反向代理。此时如果我们通过request.getRemoteAddr();可能获取到的是自身代理服务器的IP，而无法达到获取用户请求ip的目的。一下整理了各个代理服务器自己开发的转发服务请求头，这些请求头都不是标准的http请求头，不一定所有的代理都会带上这些请求头，所以通过这方式只能尽可能的获取到真实ip，但不能保证一定可以获取到真实ip，而且代理服务器请求头中获取的ip是可伪造的。
X-Forwarded-For：Squid 服务代理
Proxy-Client-IP：apache 服务代理
WL-Proxy-Client-IP：weblogic 服务代理
HTTP_CLIENT_IP：有些代理服务器
X-Real-IP：nginx服务代理
有些网络通过多层代理，那么获取到的ip就会有多个，一般都是通过逗号（,）分割开来，并且第一个ip为客户端的真实IP