http请求获取客户端IP

public String getIpAddr(HttpServletRequest request) {  
 String ip = request.getHeader("x-forwarded-for");  
 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.getRemoteAddr();  
 }  
 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_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;  
}