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TFTPAckPacket.javaAPI DocApache Commons NET 1.4.1 API5174Sat Dec 03 10:05:48 GMT 2005org.apache.commons.net.tftp

TFTPAckPacket

public final class TFTPAckPacket extends TFTPPacket
A final class derived from TFTPPacket definiing the TFTP Acknowledgement packet type.

Details regarding the TFTP protocol and the format of TFTP packets can be found in RFC 783. But the point of these classes is to keep you from having to worry about the internals. Additionally, only very few people should have to care about any of the TFTPPacket classes or derived classes. Almost all users should only be concerned with the {@link org.apache.commons.net.tftp.TFTPClient} class {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()} and {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} methods.

author
Daniel F. Savarese
see
TFTPPacket
see
TFTPPacketException
see
TFTP

Fields Summary
int
_blockNumber
The block number being acknowledged by the packet.
Constructors Summary
public TFTPAckPacket(InetAddress destination, int port, int blockNumber)
Creates an acknowledgment packet to be sent to a host at a given port acknowledging receipt of a block.

param
destination The host to which the packet is going to be sent.
param
port The port to which the packet is going to be sent.
param
blockNumber The block number being acknowledged.

        super(TFTPPacket.ACKNOWLEDGEMENT, destination, port);
        _blockNumber = blockNumber;
TFTPAckPacket(DatagramPacket datagram)
Creates an acknowledgement packet based from a received datagram. Assumes the datagram is at least length 4, else an ArrayIndexOutOfBoundsException may be thrown.

param
datagram The datagram containing the received acknowledgement.
throws
TFTPPacketException If the datagram isn't a valid TFTP acknowledgement packet.

        super(TFTPPacket.ACKNOWLEDGEMENT, datagram.getAddress(),
              datagram.getPort());
        byte[] data;

        data = datagram.getData();

        if (getType() != data[1])
            throw new TFTPPacketException("TFTP operator code does not match type.");

        _blockNumber = (((data[2] & 0xff) << 8) | (data[3] & 0xff));
Methods Summary
java.net.DatagramPacket_newDatagram(java.net.DatagramPacket datagram, byte[] data)
This is a method only available within the package for implementing efficient datagram transport by elminating buffering. It takes a datagram as an argument, and a byte buffer in which to store the raw datagram data. Inside the method, the data is set as the datagram's data and the datagram returned.

param
datagram The datagram to create.
param
data The buffer to store the packet and to use in the datagram.
return
The datagram argument.

        data[0] = 0;
        data[1] = (byte)_type;
        data[2] = (byte)((_blockNumber & 0xffff) >> 8);
        data[3] = (byte)(_blockNumber & 0xff);

        datagram.setAddress(_address);
        datagram.setPort(_port);
        datagram.setData(data);
        datagram.setLength(4);

        return datagram;
public intgetBlockNumber()
Returns the block number of the acknowledgement.

return
The block number of the acknowledgement.

        return _blockNumber;
public java.net.DatagramPacketnewDatagram()
Creates a UDP datagram containing all the TFTP acknowledgement packet data in the proper format. This is a method exposed to the programmer in case he wants to implement his own TFTP client instead of using the {@link org.apache.commons.net.tftp.TFTPClient} class. Under normal circumstances, you should not have a need to call this method.

return
A UDP datagram containing the TFTP acknowledgement packet.

        byte[] data;

        data = new byte[4];
        data[0] = 0;
        data[1] = (byte)_type;
        data[2] = (byte)((_blockNumber & 0xffff) >> 8);
        data[3] = (byte)(_blockNumber & 0xff);

        return new DatagramPacket(data, data.length, _address, _port);
public voidsetBlockNumber(int blockNumber)
Sets the block number of the acknowledgement.

        _blockNumber = blockNumber;