How can I programmatically test an HTTP connection?

Question

Using Java, how can I test that a URL is contactable, and returns a valid response?

http://stackoverflow.com/about

Solution 1

The solution as a unit test:

public void testURL() throws Exception {
    String strUrl = "http://stackoverflow.com/about";

    try {
        URL url = new URL(strUrl);
        HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
        urlConn.connect();

        assertEquals(HttpURLConnection.HTTP_OK, urlConn.getResponseCode());
    } catch (IOException e) {
        System.err.println("Error creating HTTP connection");
        e.printStackTrace();
        throw e;
    }
}

Solution 2

Since java 5 if i recall, the InetAdress class contains a method called isReachable(); so you can use it to make a ping implementation in java. You can also specify a timeout for this method. This is just another alternative to the unit test method posted above, which is probably more efficient.

Comments

[C. K. Young]

@David: No, often people ask questions they already know the answer for, just to provide more useful content for SO.

[C. K. Young]

isReachable only tests that you can reach the site, not that the site is actually running (e.g., returning 200 rather than 500 or the like).

[C. K. Young]

Also, unit tests are required more to be thorough, than efficient. :-P

[Charlie]

Far enough, apologize for the comment in that case. And thanks for sharing the solution then...

[Xitrum]

@brass-kazoo I got connection refused exception :(

[Daniel Kamil Kozar]

-1. This does not answer the question at all : the code you posted only checks if the URL is valid, not if the host under that URL is reachable or gives a given response.

[Katianie]

This is a misleading answer -1 for that.

[Enwired]

Isn't it also necessary to call urlCon.disconnect() in a finally block? And maybe also completely consume the InputStream?

[Tim Autin]

If you use it on a comuter available on your network but with no webserver running, this method will hang. You need to use setConnectTimeout and/or setReadTimeout on the HttpURLConnection.