Java后端怎么获取访问ip地址

Java后端可以通过HttpServletRequest对象的getRemoteAddr()方法来获取访问者的IP地址，示例代码如下：

import javax.servlet.http.HttpServletRequest;

public class IPUtil {
    public static String getIpAddress(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.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.getRemoteAddr();
        }
        return ip;
    }
}

在上面的代码中，我们先从请求头中获取X-Forwarded-For、Proxy-Client-IP、WL-Proxy-Client-IP、HTTP_CLIENT_IP、HTTP_X_FORWARDED_FOR等字段的值，如果这些字段都为空或unknown，则通过HttpServletRequest对象的getRemoteAddr()方法获取访问者的IP地址。