javax.mail

Class Service

java.lang.Object

javax.mail.Service

Direct Known Subclasses:

Store, Transport

public abstract class Service
extends Object

An abstract class that contains the functionality common to messaging services, such as stores and transports.

A messaging service is created from a Session and is named using a URLName. A service must be connected before it can be used. Connection events are sent to reflect its connection status.

Author:

Christopher Cotton, Bill Shannon, Kanwar Oberoi

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	debug Debug flag for this service.
protected Session	session The session from which this service was created.
protected URLName	url The URLName of this service.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Service(Session session, URLName urlname) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	addConnectionListener(ConnectionListener l) Add a listener for Connection events on this service.
void	close() Close this service and terminate its connection.
void	connect() A generic connect method that takes no parameters.
void	connect(String host, int port, String user, String password) Similar to connect(host, user, password) except a specific port can be specified.
void	connect(String user, String password) Connect to the current host using the specified username and password.
void	connect(String host, String user, String password) Connect to the specified address.
protected void	finalize() Stop the event dispatcher thread so the queue can be garbage collected.
URLName	getURLName() Return a URLName representing this service.
boolean	isConnected() Is this service currently connected?
protected void	notifyConnectionListeners(int type) Notify all ConnectionListeners.
protected boolean	protocolConnect(String host, int port, String user, String password) The service implementation should override this method to perform the actual protocol-specific connection attempt.
protected void	queueEvent(MailEvent event, Vector vector) Add the event and vector of listeners to the queue to be delivered.
void	removeConnectionListener(ConnectionListener l) Remove a Connection event listener.
protected void	setConnected(boolean connected) Set the connection state of this service.
protected void	setURLName(URLName url) Set the URLName representing this service.
String	toString() Return getURLName.toString() if this service has a URLName, otherwise it will return the default toString.

Methods inherited from class java.lang.Object

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

Field Detail

session

protected Session session

The session from which this service was created.

url

protected URLName url

The URLName of this service.

debug

protected boolean debug

Debug flag for this service. Set from the session's debug flag when this service is created.

Constructor Detail

Service

protected Service(Session session,
       URLName urlname)

Constructor.

Parameters:

session - Session object for this service

urlname - URLName object to be used for this service

Method Detail

connect

public void connect()
             throws MessagingException

A generic connect method that takes no parameters. Subclasses can implement the appropriate authentication schemes. Subclasses that need additional information might want to use some properties or might get it interactively using a popup window.

If the connection is successful, an "open" ConnectionEvent is delivered to any ConnectionListeners on this service.

Most clients should just call this method to connect to the service.

It is an error to connect to an already connected service.

The implementation provided here simply calls the following connect(String, String, String) method with nulls.

Throws:

AuthenticationFailedException - for authentication failures

MessagingException - for other failures

IllegalStateException - if the service is already connected

See Also:

ConnectionEvent

connect

public void connect(String host,
           String user,
           String password)
             throws MessagingException

Connect to the specified address. This method provides a simple authentication scheme that requires a username and password.

If the connection is successful, an "open" ConnectionEvent is delivered to any ConnectionListeners on this service.

It is an error to connect to an already connected service.

The implementation in the Service class will collect defaults for the host, user, and password from the session, from the URLName for this service, and from the supplied parameters and then call the protocolConnect method. If the protocolConnect method returns false, the user will be prompted for any missing information and the protocolConnect method will be called again. The subclass should override the protocolConnect method. The subclass should also implement the getURLName method, or use the implementation in this class.

On a successful connection, the setURLName method is called with a URLName that includes the information used to make the connection, including the password.

If the username passed in is null, a default value will be chosen as described above. If the password passed in is null and this is the first successful connection to this service, the user name and the password collected from the user will be saved as defaults for subsequent connection attempts to this same service when using other Service object instances (the connection information is typically always saved within a particular Service object instance). The password is saved using the Session method setPasswordAuthentication. If the password passed in is not null, it is not saved, on the assumption that the application is managing passwords explicitly.

Parameters:

host - the host to connect to

user - the user name

password - this user's password

Throws:

AuthenticationFailedException - for authentication failures

MessagingException - for other failures

IllegalStateException - if the service is already connected

See Also:

ConnectionEvent, Session.setPasswordAuthentication(javax.mail.URLName, javax.mail.PasswordAuthentication)

connect

public void connect(String user,
           String password)
             throws MessagingException

Connect to the current host using the specified username and password. This method is equivalent to calling the connect(host, user, password) method with null for the host name.

Parameters:

user - the user name

password - this user's password

Throws:

AuthenticationFailedException - for authentication failures

MessagingException - for other failures

IllegalStateException - if the service is already connected

Since:

JavaMail 1.4

See Also:

ConnectionEvent, Session.setPasswordAuthentication(javax.mail.URLName, javax.mail.PasswordAuthentication), connect(java.lang.String, java.lang.String, java.lang.String)

connect

public void connect(String host,
           int port,
           String user,
           String password)
             throws MessagingException

Similar to connect(host, user, password) except a specific port can be specified.

Parameters:

host - the host to connect to

port - the port to connect to (-1 means the default port)

user - the user name

password - this user's password

Throws:

AuthenticationFailedException - for authentication failures

MessagingException - for other failures

IllegalStateException - if the service is already connected

See Also:

connect(java.lang.String, java.lang.String, java.lang.String), ConnectionEvent

protocolConnect

protected boolean protocolConnect(String host,
                      int port,
                      String user,
                      String password)
                           throws MessagingException

The service implementation should override this method to perform the actual protocol-specific connection attempt. The default implementation of the connect method calls this method as needed.

The protocolConnect method should return false if a user name or password is required for authentication but the corresponding parameter is null; the connect method will prompt the user when needed to supply missing information. This method may also return false if authentication fails for the supplied user name or password. Alternatively, this method may throw an AuthenticationFailedException when authentication fails. This exception may include a String message with more detail about the failure.

The protocolConnect method should throw an exception to report failures not related to authentication, such as an invalid host name or port number, loss of a connection during the authentication process, unavailability of the server, etc.

Parameters:

host - the name of the host to connect to

port - the port to use (-1 means use default port)

user - the name of the user to login as

password - the user's password

Returns:

true if connection successful, false if authentication failed

Throws:

AuthenticationFailedException - for authentication failures

MessagingException - for non-authentication failures

isConnected

public boolean isConnected()

Is this service currently connected?

This implementation uses a private boolean field to store the connection state. This method returns the value of that field.

Subclasses may want to override this method to verify that any connection to the message store is still alive.

Returns:

true if the service is connected, false if it is not connected

setConnected

protected void setConnected(boolean connected)

Set the connection state of this service. The connection state will automatically be set by the service implementation during the connect and close methods. Subclasses will need to call this method to set the state if the service was automatically disconnected.

The implementation in this class merely sets the private field returned by the isConnected method.

Parameters:

connected - true if the service is connected, false if it is not connected

close

public void close()
           throws MessagingException

Close this service and terminate its connection. A close ConnectionEvent is delivered to any ConnectionListeners. Any Messaging components (Folders, Messages, etc.) belonging to this service are invalid after this service is closed. Note that the service is closed even if this method terminates abnormally by throwing a MessagingException.

This implementation uses setConnected(false) to set this service's connected state to false. It will then send a close ConnectionEvent to any registered ConnectionListeners. Subclasses overriding this method to do implementation specific cleanup should call this method as a last step to insure event notification, probably by including a call to super.close() in a finally clause.

Throws:

MessagingException - for errors while closing

See Also:

ConnectionEvent

getURLName

public URLName getURLName()

Return a URLName representing this service. The returned URLName does not include the password field.

Subclasses should only override this method if their URLName does not follow the standard format.

The implementation in the Service class returns (usually a copy of) the url field with the password and file information stripped out.

Returns:

the URLName representing this service

See Also:

URLName

setURLName

protected void setURLName(URLName url)

Set the URLName representing this service. Normally used to update the url field after a service has successfully connected.

Subclasses should only override this method if their URL does not follow the standard format. In particular, subclasses should override this method if their URL does not require all the possible fields supported by URLName; a new URLName should be constructed with any unneeded fields removed.

The implementation in the Service class simply sets the url field.

Parameters:

url - the URLName

See Also:

URLName

addConnectionListener

public void addConnectionListener(ConnectionListener l)

Add a listener for Connection events on this service.

The default implementation provided here adds this listener to an internal list of ConnectionListeners.

Parameters:

l - the Listener for Connection events

See Also:

ConnectionEvent

removeConnectionListener

public void removeConnectionListener(ConnectionListener l)

Remove a Connection event listener.

The default implementation provided here removes this listener from the internal list of ConnectionListeners.

Parameters:

l - the listener

See Also:

addConnectionListener(javax.mail.event.ConnectionListener)

notifyConnectionListeners

protected void notifyConnectionListeners(int type)

Notify all ConnectionListeners. Service implementations are expected to use this method to broadcast connection events.

The provided default implementation queues the event into an internal event queue. An event dispatcher thread dequeues events from the queue and dispatches them to the registered ConnectionListeners. Note that the event dispatching occurs in a separate thread, thus avoiding potential deadlock problems.

Parameters:

type - the ConnectionEvent type

toString

public String toString()

Return getURLName.toString() if this service has a URLName, otherwise it will return the default toString.

Overrides:

toString in class Object

queueEvent

protected void queueEvent(MailEvent event,
              Vector vector)

Add the event and vector of listeners to the queue to be delivered.

Parameters:

event - the event

vector - the vector of listeners

finalize

protected void finalize()
                 throws Throwable

Stop the event dispatcher thread so the queue can be garbage collected.

Overrides:

finalize in class Object

Throws:

Throwable