com.groupbyinc.common.util.net.time.TimeUDPClient Maven / Gradle / Ivy
/*
* 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.
*
*
* @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 final byte[] __dummyData = new byte[1];
private final 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);
}
}