/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.net.time; import java.io.IOException; import java.net.DatagramPacket; import java.net.InetAddress; import java.util.Date; import org.apache.commons.net.DatagramSocketClient; /*** * The TimeUDPClient class is a UDP implementation of a client for the * Time protocol described in RFC 868. To use the class, merely * open a local datagram socket with * {@link org.apache.commons.net.DatagramSocketClient#open open } * and call {@link #getTime getTime } or * {@link #getTime getDate } to retrieve the time. Then call * {@link org.apache.commons.net.DatagramSocketClient#close close } * to close the connection properly. Unlike * {@link org.apache.commons.net.time.TimeTCPClient}, * successive calls to {@link #getTime getTime } or * {@link #getDate getDate } are permitted * without re-establishing a connection. That is because UDP is a * connectionless protocol and the Time protocol is stateless. *
*
* @author Daniel F. Savarese * @see TimeTCPClient ***/ public final class TimeUDPClient extends DatagramSocketClient { /*** The default time port. It is set to 37 according to RFC 868. ***/ public static final int DEFAULT_PORT = 37; /*** * The number of seconds between 00:00 1 January 1900 and * 00:00 1 January 1970. This value can be useful for converting * time values to other formats. ***/ public static final long SECONDS_1900_TO_1970 = 2208988800L; private byte[] __dummyData = new byte[1]; private byte[] __timeData = new byte[4]; /*** * Retrieves the time from the specified server and port and * returns it. The time is the number of seconds since * 00:00 (midnight) 1 January 1900 GMT, as specified by RFC 868. * This method reads the raw 32-bit big-endian * unsigned integer from the server, converts it to a Java long, and * returns the value. *
* @param host The address of the server.
* @param port The port of the service.
* @return The time value retrieved from the server.
* @exception IOException If an error occurs while retrieving the time.
***/
public long getTime(InetAddress host, int port) throws IOException
{
long time;
DatagramPacket sendPacket, receivePacket;
sendPacket =
new DatagramPacket(__dummyData, __dummyData.length, host, port);
receivePacket = new DatagramPacket(__timeData, __timeData.length);
_socket_.send(sendPacket);
_socket_.receive(receivePacket);
time = 0L;
time |= (((__timeData[0] & 0xff) << 24) & 0xffffffffL);
time |= (((__timeData[1] & 0xff) << 16) & 0xffffffffL);
time |= (((__timeData[2] & 0xff) << 8) & 0xffffffffL);
time |= ((__timeData[3] & 0xff) & 0xffffffffL);
return time;
}
/*** Same as getTime(host, DEFAULT_PORT);
***/
public long getTime(InetAddress host) throws IOException
{
return getTime(host, DEFAULT_PORT);
}
/***
* Retrieves the time from the server and returns a Java Date
* containing the time converted to the local timezone.
*
* @param host The address of the server.
* @param port The port of the service.
* @return A Date value containing the time retrieved from the server
* converted to the local timezone.
* @exception IOException If an error occurs while fetching the time.
***/
public Date getDate(InetAddress host, int port) throws IOException
{
return new Date((getTime(host, port) - SECONDS_1900_TO_1970)*1000L);
}
/*** Same as getTime(host, DEFAULT_PORT);
***/
public Date getDate(InetAddress host) throws IOException
{
return new Date((getTime(host, DEFAULT_PORT) -
SECONDS_1900_TO_1970)*1000L);
}
}