: Class AbstractClient

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ocsf.client
Class AbstractClient

java.lang.Object
  |
  +--ocsf.client.AbstractClient

Direct Known Subclasses:: AdaptableClient, ChatClient, SimpleClient

public abstract class AbstractClient
extends java.lang.Object
implements java.lang.Runnable

The AbstractClient contains all the methods necessary to set up the client side of a client-server architecture. When a client is thus connected to the server, the two programs can then exchange Object instances.

Method handleMessageFromServer must be defined by a concrete subclass. Several other hook methods may also be overriden.

Several public service methods are provided to application that use this framework.

Project Name: OCSF (Object Client-Server Framework)

Field Summary
`private java.lang.Thread`	`clientReader` The thread created to read data from the server.
`private java.net.Socket`	`clientSocket` Sockets are used in the operating system as channels of communication between two processes.
`private java.lang.String`	`host` The server's host name.
`private java.io.ObjectInputStream`	`input` The stream to handle data from the server.
`private java.io.ObjectOutputStream`	`output` The stream to handle data going to the server.
`private int`	`port` The port number.
`private boolean`	`readyToStop` Indicates if the thread is ready to stop.

Constructor Summary
`AbstractClient(java.lang.String host, int port)` Constructs the client.

Method Summary
`private void`	`closeAll()` Closes all aspects of the connection to the server.
`void`	`closeConnection()` Closes the connection to the server.
`protected void`	`connectionClosed()` Hook method called after the connection has been closed.
`protected void`	`connectionEstablished()` Hook method called after a connection has been established.
`protected void`	`connectionException(java.lang.Exception exception)` Hook method called each time an exception is thrown by the client's thread that is waiting for messages from the server.
`java.lang.String`	`getHost()`
`java.net.InetAddress`	`getInetAddress()` returns the client's description.
`int`	`getPort()`
`protected abstract void`	`handleMessageFromServer(java.lang.Object msg)` Handles a message sent from the server to this client.
`boolean`	`isConnected()`
`void`	`openConnection()` Opens the connection with the server.
`void`	`run()` Waits for messages from the server.
`void`	`sendToServer(java.lang.Object msg)` Sends an object to the server.
`void`	`setHost(java.lang.String host)` Sets the server host for the next connection.
`void`	`setPort(int port)` Sets the server port number for the next connection.

Methods inherited from class java.lang.Object

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

Field Detail

clientSocket

private java.net.Socket clientSocket

Sockets are used in the operating system as channels of communication between two processes.

See Also:: Socket

output

private java.io.ObjectOutputStream output

The stream to handle data going to the server.

input

private java.io.ObjectInputStream input

The stream to handle data from the server.

clientReader

private java.lang.Thread clientReader

The thread created to read data from the server.

readyToStop

private boolean readyToStop

Indicates if the thread is ready to stop. Needed so that the loop in the run method knows when to stop waiting for incoming messages.

host

private java.lang.String host

The server's host name.

port

private int port

The port number.

Constructor Detail

AbstractClient

public AbstractClient(java.lang.String host,
                      int port)

Constructs the client.

Parameters:: host - the server's host name.; port - the port number.

Method Detail

openConnection

public final void openConnection()
                          throws java.io.IOException

Opens the connection with the server. If the connection is already opened, this call has no effect.

Throws:: java.io.IOException - if an I/O error occurs when opening.

sendToServer

public final void sendToServer(java.lang.Object msg)
                        throws java.io.IOException

Sends an object to the server. This is the only way that methods should communicate with the server.

Parameters:: msg - The message to be sent.
Throws:: java.io.IOException - if an I/O error occurs when sending

closeConnection

public final void closeConnection()
                           throws java.io.IOException

Closes the connection to the server.

Throws:: java.io.IOException - if an I/O error occurs when closing.

isConnected

public final boolean isConnected()

Returns:: true if the client is connnected.

getPort

public final int getPort()

Returns:: the port number.

setPort

public final void setPort(int port)

Sets the server port number for the next connection. The change in port only takes effect at the time of the next call to openConnection().

Parameters:: port - the port number.

getHost

public final java.lang.String getHost()

Returns:: the host name.

setHost

public final void setHost(java.lang.String host)

Sets the server host for the next connection. The change in host only takes effect at the time of the next call to openConnection().

Parameters:: host - the host name.

getInetAddress

public final java.net.InetAddress getInetAddress()

returns the client's description.

Returns:: the client's Inet address.

run

public final void run()

Waits for messages from the server. When each arrives, a call is made to handleMessageFromServer(). Not to be explicitly called.

Specified by:: run in interface java.lang.Runnable

connectionClosed

protected void connectionClosed()

Hook method called after the connection has been closed. The default implementation does nothing. The method may be overriden by subclasses to perform special processing such as cleaning up and terminating, or attempting to reconnect.

connectionException

protected void connectionException(java.lang.Exception exception)

Hook method called each time an exception is thrown by the client's thread that is waiting for messages from the server. The method may be overridden by subclasses.

Parameters:: exception - the exception raised.

connectionEstablished

protected void connectionEstablished()

Hook method called after a connection has been established. The default implementation does nothing. It may be overridden by subclasses to do anything they wish.

handleMessageFromServer

protected abstract void handleMessageFromServer(java.lang.Object msg)

Handles a message sent from the server to this client. This MUST be implemented by subclasses, who should respond to messages.

Parameters:: msg - the message sent.

closeAll

private void closeAll()
               throws java.io.IOException

Closes all aspects of the connection to the server.

Throws:: java.io.IOException - if an I/O error occurs when closing.