URLConnection: getLastModified()

import java.net.URL;
import java.net.URLConnection;

public class Main {
  public static void main(String[] argv) throws Exception {
    URL u = new URL("http://127.0.0.1/test.gif");
    URLConnection uc = u.openConnection();
    uc.setUseCaches(false);
    long timestamp = uc.getLastModified();

  }
}