如何获取客户端真实ip地址

    在项目中需要获取客户端的真实IP地址，原本使用的是request.getRemoteAddr()，后来发布到服务器上时发现取到的值一直是127.0.0.1

      原因是，在部署时用了nginx进行反向代理，

（小插曲：配nginx的时候一定要记得配 X-Real-IP和 X-Forwarded-For如下，不然还是取不到啊）

解决办法：

      经过代理以后，由于在客户端和服务之间增加了中间层，因此服务器无法直接拿到客户端的IP，服务器端应用也无法直接通过转发请求的地址返回给客户端。但是在转发请求的HTTP头信息中，增加了 X-Real-IP和 X-Forwarded-For信息。即可获取。

public static String getIpAddress(HttpServletRequest request) {  
        String ip = request.getHeader("x-forwarded-for");  
        String xip = request.getHeader("X-Real-IP");
        if(ip != null && ip.length()!=0 && !ip.equalsIgnoreCase("unKnown")){
        	int index = ip.indexOf(",");
        	if(index != -1){
        		return ip.substring(0,index);
        	}else{
        		return ip;
        	}
        }
        ip = xip;
        if(ip != null && ip.length()!=0 && !ip.equalsIgnoreCase("unKnown")){
        	return ip;
        }
        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;  
    }

参考：http://dpn525.iteye.com/blog/1132318