org.apache.commons.net
Class DatagramSocketClient

java.lang.Object
  org.apache.commons.net.DatagramSocketClient

Direct Known Subclasses:

CharGenUDPClient, DaytimeUDPClient, DiscardUDPClient, NTPUDPClient, TFTP, TimeUDPClient

public abstract class DatagramSocketClient
extends Object

The DatagramSocketClient provides the basic operations that are required of client objects accessing datagram sockets. It is meant to be subclassed to avoid having to rewrite the same code over and over again to open a socket, close a socket, set timeouts, etc. Of special note is the setDatagramSocketFactory method, which allows you to control the type of DatagramSocket the DatagramSocketClient creates for network communications. This is especially useful for adding things like proxy support as well as better support for applets. For example, you could create a DatagramSocketFactory that requests browser security capabilities before creating a socket. All classes derived from DatagramSocketClient should use the _socketFactory_ member variable to create DatagramSocket instances rather than instantiating them by directly invoking a constructor. By honoring this contract you guarantee that a user will always be able to provide his own Socket implementations by substituting his own SocketFactory.

Author:

Daniel F. Savarese

See Also:

DatagramSocketFactory

Field Summary

protected boolean	_isOpen_ A status variable indicating if the client's socket is currently open.
protected DatagramSocket	_socket_ The datagram socket used for the connection.
protected DatagramSocketFactory	_socketFactory_ The datagram socket's DatagramSocketFactory.
protected int	_timeout_ The timeout to use after opening a socket.

Constructor Summary

DatagramSocketClient()
Default constructor for DatagramSocketClient.

Method Summary

void	close() Closes the DatagramSocket used for the connection.
int	getDefaultTimeout() Returns the default timeout in milliseconds that is used when opening a socket.
InetAddress	getLocalAddress() Returns the local address to which the client's socket is bound.
int	getLocalPort() Returns the port number of the open socket on the local host used for the connection.
int	getSoTimeout() Returns the timeout in milliseconds of the currently opened socket.
boolean	isOpen() Returns true if the client has a currently open socket.
void	open() Opens a DatagramSocket on the local host at the first available port.
void	open(int port) Opens a DatagramSocket on the local host at a specified port.
void	open(int port, InetAddress laddr) Opens a DatagramSocket at the specified address on the local host at a specified port.
void	setDatagramSocketFactory(DatagramSocketFactory factory) Sets the DatagramSocketFactory used by the DatagramSocketClient to open DatagramSockets.
void	setDefaultTimeout(int timeout) Set the default timeout in milliseconds to use when opening a socket.
void	setSoTimeout(int timeout) Set the timeout in milliseconds of a currently open connection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_timeout_

protected int _timeout_

The timeout to use after opening a socket.

_socket_

protected DatagramSocket _socket_

The datagram socket used for the connection.

_isOpen_

protected boolean _isOpen_

A status variable indicating if the client's socket is currently open.

_socketFactory_

protected DatagramSocketFactory _socketFactory_

The datagram socket's DatagramSocketFactory.

Constructor Detail

DatagramSocketClient

public DatagramSocketClient()

Default constructor for DatagramSocketClient. Initializes _socket_ to null, _timeout_ to 0, and _isOpen_ to false.

Method Detail

open

public void open()
          throws SocketException

Opens a DatagramSocket on the local host at the first available port. Also sets the timeout on the socket to the default timeout set by setDefaultTimeout() .

_isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.

Throws:

SocketException - If the socket could not be opened or the timeout could not be set.

open

public void open(int port)
          throws SocketException

Opens a DatagramSocket on the local host at a specified port. Also sets the timeout on the socket to the default timeout set by setDefaultTimeout() .

_isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.

Parameters:

port - The port to use for the socket.

Throws:

SocketException - If the socket could not be opened or the timeout could not be set.

open

public void open(int port,
                 InetAddress laddr)
          throws SocketException

Opens a DatagramSocket at the specified address on the local host at a specified port. Also sets the timeout on the socket to the default timeout set by setDefaultTimeout() .

_isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.

Parameters:

port - The port to use for the socket.

laddr - The local address to use.

Throws:

SocketException - If the socket could not be opened or the timeout could not be set.

close

public void close()

Closes the DatagramSocket used for the connection. You should call this method after you've finished using the class instance and also before you call open() again. _isOpen_ is set to false and _socket_ is set to null. If you call this method when the client socket is not open, a NullPointerException is thrown.

isOpen

public boolean isOpen()

Returns true if the client has a currently open socket.

Returns:

True if the client has a curerntly open socket, false otherwise.

setDefaultTimeout

public void setDefaultTimeout(int timeout)

Set the default timeout in milliseconds to use when opening a socket. After a call to open, the timeout for the socket is set using this value. This method should be used prior to a call to open() and should not be confused with setSoTimeout() which operates on the currently open socket. _timeout_ contains the new timeout value.

Parameters:

timeout - The timeout in milliseconds to use for the datagram socket connection.

getDefaultTimeout

public int getDefaultTimeout()

Returns the default timeout in milliseconds that is used when opening a socket.

Returns:

The default timeout in milliseconds that is used when opening a socket.

setSoTimeout

public void setSoTimeout(int timeout)
                  throws SocketException

Set the timeout in milliseconds of a currently open connection. Only call this method after a connection has been opened by open().

Parameters:

timeout - The timeout in milliseconds to use for the currently open datagram socket connection.

Throws:

SocketException

getSoTimeout

public int getSoTimeout()
                 throws SocketException

Returns the timeout in milliseconds of the currently opened socket. If you call this method when the client socket is not open, a NullPointerException is thrown.

Returns:

The timeout in milliseconds of the currently opened socket.

Throws:

SocketException

getLocalPort

public int getLocalPort()

Returns the port number of the open socket on the local host used for the connection. If you call this method when the client socket is not open, a NullPointerException is thrown.

Returns:

The port number of the open socket on the local host used for the connection.

getLocalAddress

public InetAddress getLocalAddress()

Returns the local address to which the client's socket is bound. If you call this method when the client socket is not open, a NullPointerException is thrown.

Returns:

The local address to which the client's socket is bound.

setDatagramSocketFactory

public void setDatagramSocketFactory(DatagramSocketFactory factory)

Sets the DatagramSocketFactory used by the DatagramSocketClient to open DatagramSockets. If the factory value is null, then a default factory is used (only do this to reset the factory after having previously altered it).

Parameters:

factory - The new DatagramSocketFactory the DatagramSocketClient should use.