Java utility class to wait for ports and URL responses to be available

WaitFor.java

/**
 * General utilities to wait for ports and URL responses to be available.
 * Especially useful when waiting for container services to be fully "up".
 */
public class WaitFor {

  private static final Logger logger = LoggerFactory.getLogger(WaitFor.class.getClass());

  public static void waitForPort(String hostname, int port, long timeoutMs) {
    logger.info("Waiting for port " + port);
    long startTs = System.currentTimeMillis();
    boolean scanning=true;
    while(scanning)
    {
      if (System.currentTimeMillis() - startTs > timeoutMs) {
        throw new RuntimeException("Timeout waiting for port " + port);
      }
      try
      {
        SocketAddress addr = new InetSocketAddress(hostname, port);
        Selector.open();
        SocketChannel socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(true);
        try {
          socketChannel.connect(addr);
        }
        finally {
          socketChannel.close();
        }

        scanning=false;
      }
      catch(IOException e)
      {
        logger.debug("Still waiting for port " + port);
        try
        {
          Thread.sleep(2000);//2 seconds
        }
        catch(InterruptedException ie){
          logger.error("Interrupted", ie);
        }
      }
    }
    logger.info("Port " + port + " ready.");
  }

  public static void waitForResponse(String url, String response, int timeoutMS) {
    logger.info("Waiting " + timeoutMS + "ms for " + url + " to respond with '" + response + '"');
    long startTS = System.currentTimeMillis();
    while (System.currentTimeMillis() - startTS < timeoutMS) {
      try {
        URL urlConnect = new URL(url);
        URLConnection conn = urlConnect.openConnection();
        BufferedReader in = new BufferedReader(
            new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuilder sb = new StringBuilder();
        try {
          while ((inputLine = in.readLine()) != null) {
            sb.append(inputLine);
          }
          if (sb.toString().contains(response)) return;
        }
        finally {
          try {
            in.close();
          }
          catch (IOException e) {
            // ignore and retry ...
          }
        }
      } catch (IOException e) {
        // assume site is not available yet, retry ...
      }
    }
    throw new RuntimeException("Operation timed out");
  }
}