阿里云linux服务器，JAVA controller怎么获取不到当前的域名？

Question

如题

String url2=request.getScheme()+"://"+ request.getServerName();
        System.out.println("协议名：//域名="+url2);

        StringBuffer url = request.getRequestURL();
        String tempContextUrl = url.delete(url.length() - request.getRequestURI().length(), url.length()).append("/").toString();
        System.out.println("=========无上下文============"+tempContextUrl);

        StringBuffer url3 = request.getRequestURL();
        String tempContextUrl3 = url.delete(url.length() - request.getRequestURI().length(), url.length()).append(request.getServletContext().getContextPath()).append("/")
                .toString();
        System.out.println("=========上下文============"+tempContextUrl3);

我用上面的三个方法，获取到的都是http://127.0.0.1

我想要拿 https://www.a.com怎么拿？

nginx 配置：
location ~ ^/(xxx) {
     proxy_set_header x-forwarded-for  $remote_addr; 
     proxy_pass http://localhost:8988;
}


proxy_set_header Host $host; 加上这个我能拿到http://www.a.com
问题二：我浏览器输入的是https://www.a.com 这个https我怎么设置啊？？？？？

Answer 1

location里面加 proxy_set_header Host $host;