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jeremybenn |
/* DatagramPacket.java -- Class to model a packet to be sent via UDP
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Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.net;
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/*
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* Status: Believed complete and correct.
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*/
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/**
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* This class models a packet of data that is to be sent across the network
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* using a connectionless protocol such as UDP. It contains the data
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* to be send, as well as the destination address and port. Note that
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* datagram packets can arrive in any order and are not guaranteed to be
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* delivered at all.
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* <p>
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* This class can also be used for receiving data from the network.
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* <p>
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* Note that for all method below where the buffer length passed by the
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* caller cannot exceed the actually length of the byte array passed as
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* the buffer, if this condition is not true, then the method silently
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* reduces the length value to maximum allowable value.
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*
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* Status: Believed complete and correct.
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*
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* @author Warren Levy (warrenl@cygnus.com)
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* @author Aarom M. Renn (arenn@urbanophile.com) (Documentation comments)
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* @date April 28, 1999.
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*/
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public final class DatagramPacket
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{
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/**
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* The data buffer to send
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*/
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private byte[] buffer;
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/**
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* This is the offset into the buffer to start sending from or receiving to.
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*/
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private int offset;
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/**
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* The length of the data buffer to send.
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*/
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int length;
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/**
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* The maximal length of the buffer.
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*/
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int maxlen;
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/**
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* The address to which the packet should be sent or from which it
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* was received.
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*/
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private InetAddress address;
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/**
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* The port to which the packet should be sent or from which it was
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* was received.
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*/
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private int port;
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/**
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* This method initializes a new instance of <code>DatagramPacket</code>
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* which has the specified buffer, offset, and length.
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*
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* @param buf The buffer for holding the incoming datagram.
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* @param offset The offset into the buffer to start writing.
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* @param length The maximum number of bytes to read.
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*
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* @since 1.2
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*/
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public DatagramPacket(byte[] buf, int offset, int length)
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{
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setData(buf, offset, length);
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address = null;
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port = -1;
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}
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/**
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* Initializes a new instance of <code>DatagramPacket</code> for
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* receiving packets from the network.
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*
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* @param buf A buffer for storing the returned packet data
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* @param length The length of the buffer (must be <= buf.length)
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*/
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public DatagramPacket(byte[] buf, int length)
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{
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this(buf, 0, length);
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}
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/**
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* Initializes a new instance of <code>DatagramPacket</code> for
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* transmitting packets across the network.
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*
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* @param buf A buffer containing the data to send
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* @param offset The offset into the buffer to start writing from.
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* @param length The length of the buffer (must be <= buf.length)
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* @param address The address to send to
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* @param port The port to send to
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*
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* @since 1.2
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*/
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public DatagramPacket(byte[] buf, int offset, int length,
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InetAddress address, int port)
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{
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setData(buf, offset, length);
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setAddress(address);
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setPort(port);
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}
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/**
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* Initializes a new instance of <code>DatagramPacket</code> for
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* transmitting packets across the network.
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*
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* @param buf A buffer containing the data to send
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* @param length The length of the buffer (must be <= buf.length)
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* @param address The address to send to
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* @param port The port to send to
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*/
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public DatagramPacket(byte[] buf, int length, InetAddress address, int port)
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{
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this(buf, 0, length, address, port);
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}
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/**
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* Initializes a new instance of <code>DatagramPacket</code> for
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* transmitting packets across the network.
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*
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* @param buf A buffer containing the data to send
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* @param offset The offset into the buffer to start writing from.
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* @param length The length of the buffer (must be <= buf.length)
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* @param address The socket address to send to
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*
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* @exception SocketException If an error occurs
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* @exception IllegalArgumentException If address type is not supported
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*
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* @since 1.4
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*/
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public DatagramPacket(byte[] buf, int offset, int length,
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SocketAddress address) throws SocketException
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{
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if (! (address instanceof InetSocketAddress))
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throw new IllegalArgumentException("unsupported address type");
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InetSocketAddress tmp = (InetSocketAddress) address;
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setData(buf, offset, length);
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setAddress(tmp.getAddress());
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setPort(tmp.getPort());
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}
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/**
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* Initializes a new instance of <code>DatagramPacket</code> for
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* transmitting packets across the network.
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*
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* @param buf A buffer containing the data to send
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* @param length The length of the buffer (must be <= buf.length)
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* @param address The socket address to send to
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*
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* @exception SocketException If an error occurs
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* @exception IllegalArgumentException If address type is not supported
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*
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* @since 1.4
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*/
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public DatagramPacket(byte[] buf, int length, SocketAddress address)
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throws SocketException
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{
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this(buf, 0, length, address);
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}
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/**
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* Returns the address that this packet is being sent to or, if it was used
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* to receive a packet, the address that is was received from. If the
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* constructor that doesn not take an address was used to create this object
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* and no packet was actually read into this object, then this method
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* returns <code>null</code>.
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*
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* @return The address for this packet.
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*/
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public synchronized InetAddress getAddress()
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{
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return address;
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}
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/**
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* Returns the port number this packet is being sent to or, if it was used
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* to receive a packet, the port that it was received from. If the
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* constructor that doesn not take an address was used to create this object
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* and no packet was actually read into this object, then this method
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* will return 0.
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*
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* @return The port number for this packet
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*/
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public synchronized int getPort()
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{
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return port;
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}
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/**
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* Returns the data buffer for this packet
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*
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* @return This packet's data buffer
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*/
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public synchronized byte[] getData()
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{
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return buffer;
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}
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/**
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* This method returns the current offset value into the data buffer
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* where data will be sent from.
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*
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* @return The buffer offset.
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*
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* @since 1.2
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*/
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public synchronized int getOffset()
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{
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return offset;
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}
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/**
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* Returns the length of the data in the buffer
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*
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* @return The length of the data
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*/
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public synchronized int getLength()
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{
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return length;
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}
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/**
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* This sets the address to which the data packet will be transmitted.
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*
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* @param address The destination address
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*
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* @since 1.1
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*/
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public synchronized void setAddress(InetAddress address)
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{
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this.address = address;
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}
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/**
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* This sets the port to which the data packet will be transmitted.
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*
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* @param port The destination port
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*
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* @since 1.1
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*/
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public synchronized void setPort(int port)
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{
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if (port < 0 || port > 65535)
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throw new IllegalArgumentException("Invalid port: " + port);
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this.port = port;
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}
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/**
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* Sets the address of the remote host this package will be sent
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*
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* @param address The socket address of the remove host
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*
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* @exception IllegalArgumentException If address type is not supported
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*
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* @since 1.4
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*/
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public void setSocketAddress(SocketAddress address)
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throws IllegalArgumentException
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{
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if (address == null)
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throw new IllegalArgumentException("address may not be null");
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InetSocketAddress tmp = (InetSocketAddress) address;
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this.address = tmp.getAddress();
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this.port = tmp.getPort();
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}
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/**
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* Gets the socket address of the host this packet
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* will be sent to/is coming from
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*
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* @return The socket address of the remote host
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*
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* @since 1.4
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*/
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public SocketAddress getSocketAddress()
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{
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return new InetSocketAddress(address, port);
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}
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/**
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* Sets the data buffer for this packet.
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*
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* @param buf The new buffer for this packet
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*
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* @exception NullPointerException If the argument is null
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*
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* @since 1.1
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*/
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public void setData(byte[] buf)
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{
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setData(buf, 0, buf.length);
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}
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/**
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* This method sets the data buffer for the packet.
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*
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* @param buf The byte array containing the data for this packet.
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* @param offset The offset into the buffer to start reading data from.
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* @param length The number of bytes of data in the buffer.
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*
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* @exception NullPointerException If the argument is null
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*
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* @since 1.2
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*/
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public synchronized void setData(byte[] buf, int offset, int length)
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{
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// This form of setData must be used if offset is to be changed.
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if (buf == null)
|
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throw new NullPointerException("Null buffer");
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if (offset < 0)
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throw new IllegalArgumentException("Invalid offset: " + offset);
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buffer = buf;
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this.offset = offset;
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setLength(length);
|
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}
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|
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|
|
/**
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|
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* Sets the length of the data in the buffer.
|
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|
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*
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|
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* @param length The new length. (Where len <= buf.length)
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|
|
*
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|
|
* @exception IllegalArgumentException If the length is negative or
|
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|
|
* if the length is greater than the packet's data buffer length
|
377 |
|
|
*
|
378 |
|
|
* @since 1.1
|
379 |
|
|
*/
|
380 |
|
|
public synchronized void setLength(int length)
|
381 |
|
|
{
|
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|
|
if (length < 0)
|
383 |
|
|
throw new IllegalArgumentException("Invalid length: " + length);
|
384 |
|
|
if (offset + length > buffer.length)
|
385 |
|
|
throw new IllegalArgumentException("Potential buffer overflow - offset: "
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386 |
|
|
+ offset + " length: " + length);
|
387 |
|
|
|
388 |
|
|
this.length = length;
|
389 |
|
|
this.maxlen = length;
|
390 |
|
|
}
|
391 |
|
|
}
|