I've hunted around a bit trying to see if port 80 and port 443 are defined as public constants anywhere. Do these exist in the JDK (or perhaps in a common library such as Apache HttpClient)?
Look at Javadoc for URL: http://docs.oracle.com/javase/8/docs/api/java/net/URL.html#getDefaultPort--
getDefaultPort() returns the port for the given protocol
URL url = new URL("http://blah.com"); int defaultPort = url.getDefaultPort();