Tomcat: getHeader(“Host”) vs. getServerName()

Question

I\'ve got a Tomcat app that is being served up from multiple domains. Previous developers built a method to return the application URL (see below). In the method they reques

Answer 1

This is indeed very problematic because sometimes you don't even know where the host that you expect to be a fully qualified domain has been removed. @rickz provided a great solution, but here's another one that I consider to be more complete and covers many different urls:

Basically, you strip the protocol (http://, https://, ftp://,...) then the port (should it exist) and then the whole URI. That gives you the complete list of top level domain and subdomains.

String requestURL = request.getRequestURL().toString();
String withoutProtocol = requestURL.replaceAll("(.*\\/{2})", "")
String withoutPort = withoutProtocol.replaceAll("(:\\d*)", "") 
String domain = withoutPort.replaceAll("(\\/.*)", "")

I did this in scala using inline method definitions, but the code above is more verbose because I found it better to post the solution in pure java. So if you create methods for this you could chain them to do something like this:

removeURI(removePort(removeProtocol(requestURL)))