通過 HttpServletRequest 獲取真實請求IP

package cc.library.security.utils;

import javax.servlet.http.HttpServletRequest;

/**
 * CREATE BY funnyZpC ON 2018/5/3
 **/
public class IPUtils {
    /**
     * 獲取使用者真實IP地址，不使用request.getRemoteAddr()的原因是有可能使用者使用了代理軟體方式避免真實IP地址,
     * 可是，如果通過了多級反向代理的話，X-Forwarded-For的值並不止一個，而是一串IP值
     *
     * @return ip
     */
    public static String getRealIP(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip != null && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
            // 多次反向代理後會有多個ip值，第一個ip才是真實ip
            if( ip.indexOf(",")!=-1 ){
                ip = ip.split(",")[0];
            }
        }
        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.getHeader("X-Real-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }
}