前言

一般的系统，在正常情况下，都会去获取客户端登录用户的ip地址，当然了，肯定不是拿来做坏事，基本上会用在 异地登录检测，用于城市获取等相关上面，毕竟，违法犯罪的事情我们不做，下面提供一波获取ip地址的工具类

第一种方法

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    /**
     * 获取客户端ip地址
     * @param request
     * @return
     */
protected String getIP(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip != null) {
            ip = ip.split("\\,")[0];
        }
        if (!checkIP(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (!checkIP(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (!checkIP(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }
 
    private boolean checkIP(String ip) {
        if (ip == null || ip.length() == 0 || "unkown".equalsIgnoreCase(ip)
                || ip.split("\\.").length != 4) {
            return false;
        }
        return true;
    }

第二种方法

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/**
 * 获取客户端ip地址
 * @param request
 * @return
 */
public static String getRealIp(HttpServletRequest request) {
    String ip = request.getHeader("x-forwarded-for");
    System.out.println("x-forwarded-for ip: " + ip);
    if (ip != null && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
        // 多次反向代理后会有多个ip值，第一个ip才是真实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;
}

结语

其实，从根本上来说，第一种和第二种没有任何区别，都是一样的，只是写法不一样，至于用哪一种，则主要是看个人喜好……