URLConnection: setIfModifiedSince(long ifmodifiedsince)
import java.net.URL; import java.net.URLConnection; import java.util.Date; public class MainClass { public static void main(String[] args) { try { URLConnection uc = new URL("http://www.demo2s.com").openConnection(); System.out.println("Will retrieve file if it's been modified since " + new Date(uc.getIfModifiedSince())); uc.setIfModifiedSince(System.currentTimeMillis()); System.out.println("Will retrieve file if it's been modified since " + new Date(uc.getIfModifiedSince())); } catch (Exception e) { System.err.println(e); } } }