How to get host name with port from a http or https request

You can use HttpServletRequest.getRequestURL and HttpServletRequest.getRequestURI.

StringBuffer url = request.getRequestURL();
String uri = request.getRequestURI();
int idx = (((uri != null) && (uri.length() > 0)) ? url.indexOf(uri) : url.length());
String host = url.substring(0, idx); //base url
idx = host.indexOf("://");
if(idx > 0) {
  host = host.substring(idx); //remove scheme if present
}

If you use the load balancer & Nginx, config them without modify code.

Nginx:

proxy_set_header       Host $host;  
proxy_set_header  X-Real-IP  $remote_addr;  
proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;  
proxy_set_header X-Forwarded-Proto  $scheme;  

Tomcat's server.xml Engine:

<Valve className="org.apache.catalina.valves.RemoteIpValve"  
remoteIpHeader="X-Forwarded-For"  
protocolHeader="X-Forwarded-Proto"  
protocolHeaderHttpsValue="https"/> 

If only modify Nginx config file, the java code should be:

String XForwardedProto = request.getHeader("X-Forwarded-Proto");

You can use HttpServletRequest.getScheme() to retrieve either "http" or "https".

Using it along with HttpServletRequest.getServerName() should be enough to rebuild the portion of the URL you need.

You don't need to explicitly put the port in the URL if you're using the standard ones (80 for http and 443 for https).

Edit: If your servlet container is behind a reverse proxy or load balancer that terminates the SSL, it's a bit trickier because the requests are forwarded to the servlet container as plain http. You have a few options:

1. Use HttpServletRequest.getHeader("x-forwarded-proto") instead; this only works if your load balancer sets the header correctly (Apache should afaik).

2. Configure a RemoteIpValve in JBoss/Tomcat that will make getScheme() work as expected. Again, this will only work if the load balancer sets the correct headers.

3. If the above don't work, you could configure two different connectors in Tomcat/JBoss, one for http and one for https, as described in this article.