Java get IP

/**
 * 获取访问者IP。
 * 在一般情况下使用 Request.getRemoteAddr() 即可，但是经过 nginx 等反向代理软件后，这个方法会失效。
 */
private String getIpAddress(HttpServletRequest request) {
    // 1. 从 Header 中获取 X-Real-IP
    String ip = request.getHeader("X-Real-IP");
    if (!StringUtils.isBlank(ip) && !"unknown".equalsIgnoreCase(ip)) {
        return ip;
    }
    
    // 2. 从 X-Forwarded-For 获得第一个 IP
    ip = request.getHeader("X-Forwarded-For");
    if (!StringUtils.isBlank(ip) && !"unknown".equalsIgnoreCase(ip)) {
        // 多次反向代理后会有多个 IP 值，第一个为真实 IP。
        int index = ip.indexOf(',');

        if (index != -1) {
             return ip.substring(0, index);
        } 
        else {
            return ip;
        }
    } 
    // 3. 调用 getRemoteAddr()
    return request.getRemoteAddr();
}

If the project is deployed in the machine, accessed via localhost, get ip address in java may appear ip will be 0: 0: 0: 0: 0: 0: 0: 1.

0: 0: 0: 0: 0: 0: 0: 1 is the manifestation of ipv6, ipv4 equivalent corresponding to 127.0.0.1, which is the machine.

Logically, it should be 127.0.0.1 fishes, why the value obtained is ipv6 format?

In linux system /etc/hostsfile, just comment out the file of ::1 localhostthis line to solve the problem.

$ open /etc/hosts