How does JSP use request to get the real IP of the current visitor?

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How does JSP use request to obtain the currentWhat about the real IP of the visitor?

The following describes the method to obtain the real IP of the visitor, as follows:

When using a reverse proxy, we <%=request.getRemoteAddr() %>, it will return 127.0.0.1So how do you get the visitor's IP information?The following will come one by one, as follows:Implementation ideas:Get a visitor's real IP with the help of the following methods

 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();}return ip;}