validate that URI is valid http URI

Question

Solution

Okay I found 1 solution on Stackoverflow after a little more searching but I hope to do it with no extra libraries. http://stackoverflow.com/questions/2230676/how-to-check-for-a-valid-url-in-java/2230770#2230770

My problem:

First of hopefully this is not a duplicate, but I could not find the right answer(right away). I would like to validate that an URI(http) is valid in Java. I came up with the following tests but I can't get them to pass. First I used getPort(), but then http://www.google.nl will return -1 on getPort(). This are the test I want to have passed

Test:

@Test
public void testURI_Isvalid() throws Exception {
    assertFalse(HttpUtils.validateHTTP_URI("ttp://localhost:8080"));
    assertFalse(HttpUtils.validateHTTP_URI("ftp://localhost:8080"));
    assertFalse(HttpUtils.validateHTTP_URI("http://localhost:8a80"));
    assertTrue(HttpUtils.validateHTTP_URI("http://localhost:8080"));
    final String justWrong = 
        "/schedule/get?uri=http://localhost:8080&time=1000000";
    assertFalse(HttpUtils.validateHTTP_URI(justWrong));
    assertTrue(HttpUtils.validateHTTP_URI("http://www.google.nl"));
}

This is what I came up with after I removed the getPort() part but this does not pass all my unit tests.

Production code:

  public static boolean validateHTTP_URI(String uri) {
        final URI u;
        try {
            u = URI.create(uri);
        } catch (Exception e1) {
            return false;
        }
        return "http".equals(u.getScheme());
  }

This is the first test that is failing because I am no longer validating the getPort() part. Hopefully somebody can help me out. I think I am not using the right class to validate URLs?

P.S:

I don't want to connect to the server to validate the URI is correct. At least not yet in this step. I only want to validate scheme.

Answer 1

Code that will PASS

public static boolean validateHTTP_URI(String uri) {
    final URL url;
    try {
        url = new URL(uri);
    } catch (Exception e1) {
        return false;
    }
    return "http".equals(url.getProtocol());
}

My next Question is:

I heard/read(Joshua Bloch I believe) somewhere that Url does not work properly if you don't have internet(anymore). But I don't think that's true(anymore)? Could someone please elaborate.

Answer 2

I would maybe try to use regexp for validation, then you wouldn't need to use exception handling mechanisms for program logic, which is bad programming practice.

Try googling for a regexp that matches your needs, maybe something like this: http://snippets.dzone.com/posts/show/452

Answer 3

You could try to use this regular expression:

(?:(?<protocol>http(?:s?)|ftp)(?:\:\/\/)) (?:(?<usrpwd>\w+\:\w+)(?:\@))? (?<domain>[^/\r\n\:]+)? (?<port>\:\d+)? (?<path>(?:\/.*)*\/)? (?<filename>.*?\.(?<ext>\w{2,4}))? (?<qrystr>\??(?:\w+\=[^\#]+)(?:\&?\w+\=\w+)*)* (?<bkmrk>\#.*)?

This will tell you if an URL is valid and it will give you the protocol value. I don't know Java, so I don't know what class you need to use to validate Regular Expressions.