[java] Preferred Java way to ping an HTTP URL for availability

I need a monitor class that regularly checks whether a given HTTP URL is available. I can take care of the "regularly" part using the Spring TaskExecutor abstraction, so that's not the topic here. The question is: What is the preferred way to ping a URL in java?

Here is my current code as a starting point:

try {
    final URLConnection connection = new URL(url).openConnection();
    connection.connect();
    LOG.info("Service " + url + " available, yeah!");
    available = true;
} catch (final MalformedURLException e) {
    throw new IllegalStateException("Bad URL: " + url, e);
} catch (final IOException e) {
    LOG.info("Service " + url + " unavailable, oh no!", e);
    available = false;
}

1. Is this any good at all (will it do what I want)?
2. Do I have to somehow close the connection?
3. I suppose this is a GET request. Is there a way to send HEAD instead?

Instead of using URLConnection use HttpURLConnection by calling openConnection() on your URL object.

Then use getResponseCode() will give you the HTTP response once you've read from the connection.

here is code:

    HttpURLConnection connection = null;
    try {
        URL u = new URL("http://www.google.com/");
        connection = (HttpURLConnection) u.openConnection();
        connection.setRequestMethod("HEAD");
        int code = connection.getResponseCode();
        System.out.println("" + code);
        // You can determine on HTTP return code received. 200 is success.
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        if (connection != null) {
            connection.disconnect();
        }
    }

Also check similar question How to check if a URL exists or returns 404 with Java?

Hope this helps.

here the writer suggests this:

public boolean isOnline() {
    Runtime runtime = Runtime.getRuntime();
    try {
        Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
        int     exitValue = ipProcess.waitFor();
        return (exitValue == 0);
    } catch (IOException | InterruptedException e) { e.printStackTrace(); }
    return false;
}

Possible Questions

• Is this really fast enough?Yes, very fast!
• Couldn’t I just ping my own page, which I want to request anyways? Sure! You could even check both, if you want to differentiate between “internet connection available” and your own servers beeing reachable What if the DNS is down? Google DNS (e.g. 8.8.8.8) is the largest public DNS service in the world. As of 2013 it serves 130 billion requests a day. Let ‘s just say, your app not responding would probably not be the talk of the day.

read the link. its seems very good

EDIT: in my exp of using it, it's not as fast as this method:

public boolean isOnline() {
    NetworkInfo netInfo = connectivityManager.getActiveNetworkInfo();
    return netInfo != null && netInfo.isConnectedOrConnecting();
}

they are a bit different but in the functionality for just checking the connection to internet the first method may become slow due to the connection variables.

The following code performs a HEAD request to check whether the website is available or not.

public static boolean isReachable(String targetUrl) throws IOException
{
    HttpURLConnection httpUrlConnection = (HttpURLConnection) new URL(
            targetUrl).openConnection();
    httpUrlConnection.setRequestMethod("HEAD");

    try
    {
        int responseCode = httpUrlConnection.getResponseCode();

        return responseCode == HttpURLConnection.HTTP_OK;
    } catch (UnknownHostException noInternetConnection)
    {
        return false;
    }
}

You could also use HttpURLConnection, which allows you to set the request method (to HEAD for example). Here's an example that shows how to send a request, read the response, and disconnect.

Consider using the Restlet framework, which has great semantics for this sort of thing. It's powerful and flexible.

The code could be as simple as:

Client client = new Client(Protocol.HTTP);
Response response = client.get(url);
if (response.getStatus().isError()) {
    // uh oh!
}