How to check given domain name http or https in java?

Question

My problem

In my android application I get url input from user, like \"www.google.com\".

I want to find out for the given url whether to use

Answer 1

A domain name is a domain name, it has nothing to do with protocol. The domain is the WHERE, the protocol is the HOW.

The domain is the location you want to go, the protocol is how do you go there, by bus, by plane, by train or by boat. It makes no sense to ask 'I want to go to the store, how do I ask the store if I should go by train or by car?'

The reason this works in browsers is that the browser usually tries to connect using both http and https if no protocol is supplied.

If you know the URL, do this:

    public void decideProtocol(URL url) throws IOException {
            if ("https".equals(url.getProtocol())) { 
                // It is https
            } else if ("http".equals(url.getProtocol())) {
                // It is http
            }
    }

Answer 2

You can check, the given url is http or https by using URLUtils.

URLUtil.isHttpUrl(String url); returns True if the url is an http.

URLUtil.isHttpsUrl(String url); returns True if the url is an https.

Answer 3

You could use the Apache UrlValidator.

You can specify the allowed url schema and in your case the code look something like this:

String[] schema = {"https"};
UrlValidator urlValidator = new UrlValidator(schemes);

if (urlValidator.isValid("http://foo.bar.com/")) {
   System.out.println("url is valid");
} else {
   System.out.println("url is invalid");
}

if (urlValidator.isValid("https://foo.bar.com/")) {
   System.out.println("url is valid");
} else {
   System.out.println("url is invalid");
}

Answer 4

A hierarchical URI is subject to further parsing according to the syntax [scheme:][//authority][path][?query][#fragment]

so your url_name lack of scheme. if url_name is "https://www.google.com", so the scheme is https.

refer： http://docs.oracle.com/javase/7/docs/api/java/net/URI.html

Answer 5

ranjith- I will store some sort of mapping between URI (main domain) and preferred protcol within application..can have pre-defined mappings based on what you know and then let that mapping grow as more Uris added..

Answer 6

As was pointed out, if a user didn't dare to provide full url including protocol type. The app might use kind of trial and error approach, try to establish connection using the list of available protocols. (http, https). The successful hit might be considered as a default. Again, all this about usability,this method is better than just annoying an inattentive user with ugly error message.