org.apache.commons.net

Class DatagramSocketClient

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:

Field Summary
protected boolean_isOpen_
A status variable indicating if the client's socket is currently open.
protected DatagramSocketFactory_socketFactory_
The datagram socket's DatagramSocketFactory.
protected DatagramSocket_socket_
The datagram socket used for the connection.
protected int_timeout_
The timeout to use after opening a socket.
Constructor Summary
DatagramSocketClient()
Default constructor for DatagramSocketClient.
Method Summary
voidclose()
Closes the DatagramSocket used for the connection.
intgetDefaultTimeout()
Returns the default timeout in milliseconds that is used when opening a socket.
InetAddressgetLocalAddress()
Returns the local address to which the client's socket is bound.
intgetLocalPort()
Returns the port number of the open socket on the local host used for the connection.
intgetSoTimeout()
Returns the timeout in milliseconds of the currently opened socket.
booleanisOpen()
Returns true if the client has a currently open socket.
voidopen()
Opens a DatagramSocket on the local host at the first available port.
voidopen(int port)
Opens a DatagramSocket on the local host at a specified port.
voidopen(int port, InetAddress laddr)
Opens a DatagramSocket at the specified address on the local host at a specified port.
voidsetDatagramSocketFactory(DatagramSocketFactory factory)
Sets the DatagramSocketFactory used by the DatagramSocketClient to open DatagramSockets.
voidsetDefaultTimeout(int timeout)
Set the default timeout in milliseconds to use when opening a socket.
voidsetSoTimeout(int timeout)
Set the timeout in milliseconds of a currently open connection.

Field Detail

_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. **

_socket_

protected DatagramSocket _socket_
The datagram socket used for the connection. **

_timeout_

protected int _timeout_
The timeout to use after opening a socket. **

Constructor Detail

DatagramSocketClient

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

Method Detail

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.

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.

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.

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.

getSoTimeout

public int getSoTimeout()
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.

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.

open

public void open()
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)
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)
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.

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.

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.

setSoTimeout

public void setSoTimeout(int timeout)
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.