获得客户端的真实IP

public class IPUtil {
public static String getIpAddr(HttpServletRequest request) {
String ip = request.getHeader("X-Real-IP");
if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
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();
}
//防止多级代理时返回过个ip。
if(ip != null && ip.indexOf(",") != -1){
ip= ip.substring(0,ip.indexOf(","));
}
return ip;
}
}