XMLHttpRequest如何获取客户端主机的网络IP地址

通过此方法将request传入，即可获取到远端登陆客户端主机的网络IP地址：

public String getIpAddr(HttpServletRequest request) {

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();
}
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");
}
// 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;
}