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  /*
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 package org.apache.commons.net.tftp;
 
 
 import  org.apache.commons.net.DatagramSocketClient;

The TFTP class exposes a set of methods to allow you to deal with the TFTP protocol directly, in case you want to write your own TFTP client or server. However, almost every user should only be concerend with the open() , and close() , methods. Additionally,the a setDefaultTimeout() method may be of importance for performance tuning.

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.

See also:
org.apache.commons.net.DatagramSocketClient
TFTPPacket
TFTPPacketException
TFTPClient
 
 
 public class TFTP extends DatagramSocketClient
 {
    
The ascii transfer mode. Its value is 0 and equivalent to NETASCII_MODE
 
     public static final int ASCII_MODE = 0;

    
The netascii transfer mode. Its value is 0.
 
     public static final int NETASCII_MODE = 0;

    
The binary transfer mode. Its value is 1 and equivalent to OCTET_MODE.
 
     public static final int BINARY_MODE = 1;

    
The image transfer mode. Its value is 1 and equivalent to OCTET_MODE.
 
     public static final int IMAGE_MODE = 1;

    
The octet transfer mode. Its value is 1.
 
     public static final int OCTET_MODE = 1;

    
The default number of milliseconds to wait to receive a datagram before timing out. The default is 5000 milliseconds (5 seconds).
 
     public static final int DEFAULT_TIMEOUT = 5000;

    
The default TFTP port according to RFC 783 is 69.
 
     public static final int DEFAULT_PORT = 69;

    
The size to use for TFTP packet buffers. Its 4 plus the TFTPPacket.SEGMENT_SIZE, i.e. 516.
 
     static final int PACKET_SIZE = . + 4;

    
A buffer used to accelerate receives in bufferedReceive() *
 
     private byte[] __receiveBuffer;

    
A datagram used to minimize memory allocation in bufferedReceive() *
 
     private DatagramPacket __receiveDatagram;

    
A datagram used to minimize memory allocation in bufferedSend() *
 
     private DatagramPacket __sendDatagram;

    
A buffer used to accelerate sends in bufferedSend(). It is left package visible so that TFTPClient may be slightly more efficient during file sends. It saves the creation of an additional buffer and prevents a buffer copy in _newDataPcket().
    byte[] _sendBuffer;


    
Returns the TFTP string representation of a TFTP transfer mode. Will throw an ArrayIndexOutOfBoundsException if an invalid transfer mode is specified.

Parameters:
mode The TFTP transfer mode. One of the MODE constants.
Returns:
The TFTP string representation of the TFTP transfer mode.
    public static final String getModeName(int mode)
    {
        return .[mode];
    }

    
Creates a TFTP instance with a default timeout of DEFAULT_TIMEOUT, a null socket, and buffered operations disabled.
    public TFTP()
    {
         = null;
         = null;
    }

    
This method synchronizes a connection by discarding all packets that may be in the local socket buffer. This method need only be called when you implement your own TFTP client or server.

Throws:
IOException if an I/O error occurs.
    public final void discardPackets() throws IOException
    {
        int to;
        DatagramPacket datagram;
        datagram = new DatagramPacket(new byte[], );
        to = getSoTimeout();
        setSoTimeout(1);
        try
        {
            while (true) {
                _socket_.receive(datagram);
            }
        }
        catch (SocketException e)
        {
            // Do nothing.  We timed out so we hope we're caught up.
        }
        catch (InterruptedIOException e)
        {
            // Do nothing.  We timed out so we hope we're caught up.
        }
        setSoTimeout(to);
    }


    
This is a special method to perform a more efficient packet receive. It should only be used after calling beginBufferedOps() . beginBufferedOps() initializes a set of buffers used internally that prevent the new allocation of a DatagramPacket and byte array for each send and receive. To use these buffers you must call the bufferedReceive() and bufferedSend() methods instead of send() and receive(). You must also be certain that you don't manipulate the resulting packet in such a way that it interferes with future buffered operations. For example, a TFTPDataPacket received with bufferedReceive() will have a reference to the internal byte buffer. You must finish using this data before calling bufferedReceive() again, or else the data will be overwritten by the the call.

Returns:
The TFTPPacket received.
Throws:
InterruptedIOException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe.
SocketException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe.
IOException If some other I/O error occurs.
TFTPPacketException If an invalid TFTP packet is received.
    public final TFTPPacket bufferedReceive() throws IOException,
    {
        _socket_.receive();
        return TFTPPacket.newTFTPPacket();
    }

    
This is a special method to perform a more efficient packet send. It should only be used after calling beginBufferedOps() . beginBufferedOps() initializes a set of buffers used internally that prevent the new allocation of a DatagramPacket and byte array for each send and receive. To use these buffers you must call the bufferedReceive() and bufferedSend() methods instead of send() and receive(). You must also be certain that you don't manipulate the resulting packet in such a way that it interferes with future buffered operations. For example, a TFTPDataPacket received with bufferedReceive() will have a reference to the internal byte buffer. You must finish using this data before calling bufferedReceive() again, or else the data will be overwritten by the the call.

Parameters:
packet The TFTP packet to send.
Throws:
IOException If some I/O error occurs.
    public final void bufferedSend(TFTPPacket packetthrows IOException
    {
        _socket_.send(packet._newDatagram());
    }


    
Initializes the internal buffers. Buffers are used by bufferedSend() and bufferedReceive() . This method must be called before calling either one of those two methods. When you finish using buffered operations, you must call endBufferedOps() .
    public final void beginBufferedOps()
    {
         = new byte[];
         =
            new DatagramPacket(.);
         = new byte[];
         =
            new DatagramPacket(.);
    }

    
Releases the resources used to perform buffered sends and receives.
    public final void endBufferedOps()
    {
         = null;
         = null;
         = null;
         = null;
    }


    
Sends a TFTP packet to its destination.

Parameters:
packet The TFTP packet to send.
Throws:
IOException If some I/O error occurs.
    public final void send(TFTPPacket packetthrows IOException
    {
        _socket_.send(packet.newDatagram());
    }


    
Receives a TFTPPacket.

Returns:
The TFTPPacket received.
Throws:
InterruptedIOException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe.
SocketException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe.
IOException If some other I/O error occurs.
TFTPPacketException If an invalid TFTP packet is received.
    public final TFTPPacket receive() throws IOExceptionInterruptedIOException,
                SocketExceptionTFTPPacketException
    {
        DatagramPacket packet;
        packet = new DatagramPacket(new byte[], );
        _socket_.receive(packet);
        return TFTPPacket.newTFTPPacket(packet);
    }
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