URL: openConnection()

import java.io.BufferedInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import java.util.Date;

public class Main {

  public static void main(String[] args) throws Exception {
    Date today = new Date();
    long millisecondsPerDay = 24 * 60 * 60 * 1000;

    URL u = new URL("http://www.java2s.com");
    URLConnection uc = u.openConnection();
    uc.setIfModifiedSince((new Date(today.getTime() - millisecondsPerDay)).getTime());
    InputStream in = new BufferedInputStream(uc.getInputStream());
    Reader r = new InputStreamReader(in);
    int c;
    while ((c = r.read()) != -1) {
      System.out.print((char) c);
    }
  }

}