request如何获取IP

转自：http://www.cnblogs.com/icerainsoft/p/3584532.html

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();  
   }