Package org.apache.commons.net.tftp
Class TFTPPacket
- java.lang.Object
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- org.apache.commons.net.tftp.TFTPPacket
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- Direct Known Subclasses:
TFTPAckPacket
,TFTPDataPacket
,TFTPErrorPacket
,TFTPRequestPacket
public abstract class TFTPPacket extends java.lang.Object
TFTPPacket is an abstract class encapsulating the functionality common to the 5 types of TFTP packets. It also provides a static factory method that will create the correct TFTP packet instance from a datagram. This relieves the programmer from having to figure out what kind of TFTP packet is contained in a datagram and create it himself.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
TFTPClient
classreceiveFile()
andsendFile()
methods.- See Also:
TFTPPacketException
,TFTP
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Field Summary
Fields Modifier and Type Field Description (package private) java.net.InetAddress
_address
The host the packet is going to be sent or where it came from.(package private) int
_port
The port the packet came from or is going to.(package private) int
_type
The type of packet.static int
ACKNOWLEDGEMENT
This is the actual TFTP spec identifier and is equal to 4.static int
DATA
This is the actual TFTP spec identifier and is equal to 3.static int
ERROR
This is the actual TFTP spec identifier and is equal to 5.(package private) static int
MIN_PACKET_SIZE
The minimum size of a packet.static int
READ_REQUEST
This is the actual TFTP spec identifier and is equal to 1.static int
SEGMENT_SIZE
The TFTP data packet maximum segment size in bytes.static int
WRITE_REQUEST
This is the actual TFTP spec identifier and is equal to 2.
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Constructor Summary
Constructors Constructor Description TFTPPacket(int type, java.net.InetAddress address, int port)
This constructor is not visible outside of the package.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description (package private) abstract java.net.DatagramPacket
_newDatagram(java.net.DatagramPacket datagram, byte[] data)
This is an abstract method only available within the package for implementing efficient datagram transport by elminating buffering.java.net.InetAddress
getAddress()
Returns the address of the host where the packet is going to be sent or where it came from.int
getPort()
Returns the port where the packet is going to be sent or where it came from.int
getType()
Returns the type of the packet.abstract java.net.DatagramPacket
newDatagram()
Creates a UDP datagram containing all the TFTP packet data in the proper format.static TFTPPacket
newTFTPPacket(java.net.DatagramPacket datagram)
When you receive a datagram that you expect to be a TFTP packet, you use this factory method to create the proper TFTPPacket object encapsulating the data contained in that datagram.void
setAddress(java.net.InetAddress address)
Sets the host address where the packet is going to be sent.void
setPort(int port)
Sets the port where the packet is going to be sent.java.lang.String
toString()
For debugging
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Field Detail
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MIN_PACKET_SIZE
static final int MIN_PACKET_SIZE
The minimum size of a packet. This is 4 bytes. It is enough to store the opcode and blocknumber or other required data depending on the packet type.- See Also:
- Constant Field Values
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READ_REQUEST
public static final int READ_REQUEST
This is the actual TFTP spec identifier and is equal to 1. Identifier returned bygetType()
indicating a read request packet.- See Also:
- Constant Field Values
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WRITE_REQUEST
public static final int WRITE_REQUEST
This is the actual TFTP spec identifier and is equal to 2. Identifier returned bygetType()
indicating a write request packet.- See Also:
- Constant Field Values
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DATA
public static final int DATA
This is the actual TFTP spec identifier and is equal to 3. Identifier returned bygetType()
indicating a data packet.- See Also:
- Constant Field Values
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ACKNOWLEDGEMENT
public static final int ACKNOWLEDGEMENT
This is the actual TFTP spec identifier and is equal to 4. Identifier returned bygetType()
indicating an acknowledgement packet.- See Also:
- Constant Field Values
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ERROR
public static final int ERROR
This is the actual TFTP spec identifier and is equal to 5. Identifier returned bygetType()
indicating an error packet.- See Also:
- Constant Field Values
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SEGMENT_SIZE
public static final int SEGMENT_SIZE
The TFTP data packet maximum segment size in bytes. This is 512 and is useful for those familiar with the TFTP protocol who want to use theTFTP
class methods to implement their own TFTP servers or clients.- See Also:
- Constant Field Values
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_type
int _type
The type of packet.
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_port
int _port
The port the packet came from or is going to.
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_address
java.net.InetAddress _address
The host the packet is going to be sent or where it came from.
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Constructor Detail
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TFTPPacket
TFTPPacket(int type, java.net.InetAddress address, int port)
This constructor is not visible outside of the package. It is used by subclasses within the package to initialize base data.- Parameters:
type
- The type of the packet.address
- The host the packet came from or is going to be sent.port
- The port the packet came from or is going to be sent.
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Method Detail
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newTFTPPacket
public static final TFTPPacket newTFTPPacket(java.net.DatagramPacket datagram) throws TFTPPacketException
When you receive a datagram that you expect to be a TFTP packet, you use this factory method to create the proper TFTPPacket object encapsulating the data contained in that datagram. This method is the only way you can instantiate a TFTPPacket derived class from a datagram.- Parameters:
datagram
- The datagram containing a TFTP packet.- Returns:
- The TFTPPacket object corresponding to the datagram.
- Throws:
TFTPPacketException
- If the datagram does not contain a valid TFTP packet.
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_newDatagram
abstract java.net.DatagramPacket _newDatagram(java.net.DatagramPacket datagram, byte[] data)
This is an abstract 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 should be set as the datagram's data and the datagram returned.- Parameters:
datagram
- The datagram to create.data
- The buffer to store the packet and to use in the datagram.- Returns:
- The datagram argument.
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newDatagram
public abstract java.net.DatagramPacket newDatagram()
Creates a UDP datagram containing all the TFTP packet data in the proper format. This is an abstract method, exposed to the programmer in case he wants to implement his own TFTP client instead of using theTFTPClient
class. Under normal circumstances, you should not have a need to call this method.- Returns:
- A UDP datagram containing the TFTP packet.
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getType
public final int getType()
Returns the type of the packet.- Returns:
- The type of the packet.
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getAddress
public final java.net.InetAddress getAddress()
Returns the address of the host where the packet is going to be sent or where it came from.- Returns:
- The type of the packet.
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getPort
public final int getPort()
Returns the port where the packet is going to be sent or where it came from.- Returns:
- The port where the packet came from or where it is going.
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setPort
public final void setPort(int port)
Sets the port where the packet is going to be sent.- Parameters:
port
- the port to set
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setAddress
public final void setAddress(java.net.InetAddress address)
Sets the host address where the packet is going to be sent.- Parameters:
address
- the address to set
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toString
public java.lang.String toString()
For debugging- Overrides:
toString
in classjava.lang.Object
- Since:
- 3.6
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