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package javax.mail;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Vector;
import javax.mail.event.ConnectionEvent;
import javax.mail.event.ConnectionListener;
import javax.mail.event.MailEvent;
/**
* An abstract class that contains the functionality
* common to messaging services, such as stores and transports. <p>
* A messaging service is created from a <code>Session</code> and is
* named using a <code>URLName</code>. A service must be connected
* before it can be used. Connection events are sent to reflect
* its connection status.
*
* @author Christopher Cotton
* @author Bill Shannon
* @author Kanwar Oberoi
*/
public abstract class Service {
/**
* The session from which this service was created.
*/
protected Session session;
/**
* The <code>URLName</code> of this service.
*/
protected URLName url = null;
/**
* Debug flag for this service. Set from the session's debug
* flag when this service is created.
*/
protected boolean debug = false;
private boolean connected = false;
/*
* connectionListeners is a Vector, initialized here,
* because we depend on it always existing and depend
* on the synchronization that Vector provides.
* (Sychronizing on the Service object itself can cause
* deadlocks when notifying listeners.)
*/
private final Vector connectionListeners = new Vector();
/**
* Constructor.
*
* @param session Session object for this service
* @param urlname URLName object to be used for this service
*/
protected Service(Session session, URLName urlname) {
this.session = session;
url = urlname;
debug = session.getDebug();
}
/**
* 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. <p>
*
* If the connection is successful, an "open" <code>ConnectionEvent</code>
* is delivered to any <code>ConnectionListeners</code> on this service. <p>
*
* Most clients should just call this method to connect to the service.<p>
*
* It is an error to connect to an already connected service. <p>
*
* The implementation provided here simply calls the following
* <code>connect(String, String, String)</code> method with nulls.
*
* @exception AuthenticationFailedException for authentication failures
* @exception MessagingException for other failures
* @exception IllegalStateException if the service is already connected
*
* @see javax.mail.event.ConnectionEvent
*/
public void connect() throws MessagingException {
connect(null, null, null);
}
/**
* Connect to the specified address. This method provides a simple
* authentication scheme that requires a username and password. <p>
*
* If the connection is successful, an "open" <code>ConnectionEvent</code>
* is delivered to any <code>ConnectionListeners</code> on this service. <p>
*
* It is an error to connect to an already connected service. <p>
*
* The implementation in the Service class will collect defaults
* for the host, user, and password from the session, from the
* <code>URLName</code> for this service, and from the supplied
* parameters and then call the <code>protocolConnect</code> method.
* If the <code>protocolConnect</code> method returns <code>false</code>,
* the user will be prompted for any missing information and the
* <code>protocolConnect</code> method will be called again. The
* subclass should override the <code>protocolConnect</code> method.
* The subclass should also implement the <code>getURLName</code>
* method, or use the implementation in this class. <p>
*
* On a successful connection, the <code>setURLName</code> method is
* called with a URLName that includes the information used to make
* the connection, including the password. <p>
*
* 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 <code>setPasswordAuthentication</code>. If the
* password passed in is not null, it is not saved, on the assumption
* that the application is managing passwords explicitly.
*
* @param host the host to connect to
* @param user the user name
* @param password this user's password
* @exception AuthenticationFailedException for authentication failures
* @exception MessagingException for other failures
* @exception IllegalStateException if the service is already connected
* @see javax.mail.event.ConnectionEvent
* @see javax.mail.Session#setPasswordAuthentication
*/
public void connect(String host, String user, String password)
throws MessagingException {
connect(host, -1, user, password);
}
/**
* Connect to the current host using the specified username
* and password. This method is equivalent to calling the
* <code>connect(host, user, password)</code> method with null
* for the host name.
*
* @param user the user name
* @param password this user's password
* @exception AuthenticationFailedException for authentication failures
* @exception MessagingException for other failures
* @exception IllegalStateException if the service is already connected
* @see javax.mail.event.ConnectionEvent
* @see javax.mail.Session#setPasswordAuthentication
* @see #connect(java.lang.String, java.lang.String, java.lang.String)
* @since JavaMail 1.4
*/
public void connect(String user, String password) throws MessagingException {
connect(null, user, password);
}
/**
* Similar to connect(host, user, password) except a specific port
* can be specified.
*
* @param host the host to connect to
* @param port the port to connect to (-1 means the default port)
* @param user the user name
* @param password this user's password
* @exception AuthenticationFailedException for authentication failures
* @exception MessagingException for other failures
* @exception IllegalStateException if the service is already connected
* @see #connect(java.lang.String, java.lang.String, java.lang.String)
* @see javax.mail.event.ConnectionEvent
*/
public synchronized void connect(String host, int port,
String user, String password) throws MessagingException {
// see if the service is already connected
if (isConnected())
throw new IllegalStateException("already connected");
PasswordAuthentication pw;
boolean connected = false;
boolean save = false;
String protocol = null;
String file = null;
// get whatever information we can from the URL
// XXX - url should always be non-null here, Session
// passes it into the constructor
if (url != null) {
protocol = url.getProtocol();
if (host == null)
host = url.getHost();
if (port == -1)
port = url.getPort();
if (user == null) {
user = url.getUsername();
if (password == null) // get password too if we need it
password = url.getPassword();
} else {
if (password == null && user.equals(url.getUsername()))
// only get the password if it matches the username
password = url.getPassword();
}
file = url.getFile();
}
// try to get protocol-specific default properties
if (protocol != null) {
if (host == null)
host = session.getProperty("mail." + protocol + ".host");
if (user == null)
user = session.getProperty("mail." + protocol + ".user");
}
// try to get mail-wide default properties
if (host == null)
host = session.getProperty("mail.host");
if (user == null)
user = session.getProperty("mail.user");
// try using the system username
if (user == null) {
try {
user = System.getProperty("user.name");
} catch (SecurityException sex) {
if (debug)
sex.printStackTrace(session.getDebugOut());
}
}
// if we don't have a password, look for saved authentication info
if (password == null && url != null) {
// canonicalize the URLName
setURLName(new URLName(protocol, host, port, file, user, null));
pw = session.getPasswordAuthentication(getURLName());
if (pw != null) {
if (user == null) {
user = pw.getUserName();
password = pw.getPassword();
} else if (user.equals(pw.getUserName())) {
password = pw.getPassword();
}
} else
save = true;
}
// try connecting, if the protocol needs some missing
// information (user, password) it will not connect.
// if it tries to connect and fails, remember why for later.
AuthenticationFailedException authEx = null;
try {
connected = protocolConnect(host, port, user, password);
} catch (AuthenticationFailedException ex) {
authEx = ex;
}
// if not connected, ask the user and try again
if (!connected) {
InetAddress addr;
try {
addr = InetAddress.getByName(host);
} catch (UnknownHostException e) {
addr = null;
}
pw = session.requestPasswordAuthentication(
addr, port,
protocol,
null, user);
if (pw != null) {
user = pw.getUserName();
password = pw.getPassword();
// have the service connect again
connected = protocolConnect(host, port, user, password);
}
}
// if we're not connected by now, we give up
if (!connected) {
if (authEx != null)
throw authEx;
else
throw new AuthenticationFailedException("failed to connect");
}
setURLName(new URLName(protocol, host, port, file, user, password));
if (save)
session.setPasswordAuthentication(getURLName(),
new PasswordAuthentication(user, password));
// set our connected state
setConnected(true);
// finally, deliver the connection event
notifyConnectionListeners(ConnectionEvent.OPENED);
}
/**
* The service implementation should override this method to
* perform the actual protocol-specific connection attempt.
* The default implementation of the <code>connect</code> method
* calls this method as needed. <p>
*
* The <code>protocolConnect</code> method should return
* <code>false</code> if a user name or password is required
* for authentication but the corresponding parameter is null;
* the <code>connect</code> method will prompt the user when
* needed to supply missing information. This method may
* also return <code>false</code> 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. <p>
*
* The <code>protocolConnect</code> 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.
*
* @param host the name of the host to connect to
* @param port the port to use (-1 means use default port)
* @param user the name of the user to login as
* @param password the user's password
* @return true if connection successful, false if authentication failed
* @exception AuthenticationFailedException for authentication failures
* @exception MessagingException for non-authentication failures
*/
protected boolean protocolConnect(String host, int port, String user,
String password) throws MessagingException {
return false;
}
/**
* Is this service currently connected? <p>
*
* This implementation uses a private boolean field to
* store the connection state. This method returns the value
* of that field. <p>
*
* Subclasses may want to override this method to verify that any
* connection to the message store is still alive.
*
* @return true if the service is connected, false if it is not connected
*/
public synchronized boolean isConnected() {
return connected;
}
/**
* Set the connection state of this service. The connection state
* will automatically be set by the service implementation during the
* <code>connect</code> and <code>close</code> methods.
* Subclasses will need to call this method to set the state
* if the service was automatically disconnected. <p>
*
* The implementation in this class merely sets the private field
* returned by the <code>isConnected</code> method.
*
* @param connected true if the service is connected,
* false if it is not connected
*/
protected synchronized void setConnected(boolean connected) {
this.connected = connected;
}
/**
* 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. <p>
*
* This implementation uses <code>setConnected(false)</code> to set
* this service's connected state to <code>false</code>. 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 <code>super.close()</code>
* in a <code>finally</code> clause.
*
* @see javax.mail.event.ConnectionEvent
* @throws MessagingException for errors while closing
*/
public synchronized void close() throws MessagingException {
setConnected(false);
notifyConnectionListeners(ConnectionEvent.CLOSED);
}
/**
* Return a URLName representing this service. The returned URLName
* does <em>not</em> include the password field. <p>
*
* Subclasses should only override this method if their
* URLName does not follow the standard format. <p>
*
* The implementation in the Service class returns (usually a copy of)
* the <code>url</code> field with the password and file information
* stripped out.
*
* @return the URLName representing this service
* @see URLName
*/
public synchronized URLName getURLName() {
if (url != null && (url.getPassword() != null || url.getFile() != null))
return new URLName(url.getProtocol(), url.getHost(),
url.getPort(), null /* no file */,
url.getUsername(), null /* no password */);
else
return url;
}
/**
* Set the URLName representing this service.
* Normally used to update the <code>url</code> field
* after a service has successfully connected. <p>
*
* 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
* <code>URLName</code>; a new <code>URLName</code> should
* be constructed with any unneeded fields removed. <p>
*
* The implementation in the Service class simply sets the
* <code>url</code> field.
*
* @see URLName
*/
protected synchronized void setURLName(URLName url) {
this.url = url;
}
/**
* Add a listener for Connection events on this service. <p>
*
* The default implementation provided here adds this listener
* to an internal list of ConnectionListeners.
*
* @param l the Listener for Connection events
* @see javax.mail.event.ConnectionEvent
*/
public void addConnectionListener(ConnectionListener l) {
connectionListeners.addElement(l);
}
/**
* Remove a Connection event listener. <p>
*
* The default implementation provided here removes this listener
* from the internal list of ConnectionListeners.
*
* @param l the listener
* @see #addConnectionListener
*/
public void removeConnectionListener(ConnectionListener l) {
connectionListeners.removeElement(l);
}
/**
* Notify all ConnectionListeners. Service implementations are
* expected to use this method to broadcast connection events. <p>
*
* 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.
*/
protected void notifyConnectionListeners(int type) {
/*
* Don't bother queuing an event if there's no listeners.
* Yes, listeners could be removed after checking, which
* just makes this an expensive no-op.
*/
if (connectionListeners.size() > 0) {
ConnectionEvent e = new ConnectionEvent(this, type);
queueEvent(e, connectionListeners);
}
/* Fix for broken JDK1.1.x Garbage collector :
* The 'conservative' GC in JDK1.1.x occasionally fails to
* garbage-collect Threads which are in the wait state.
* This would result in thread (and consequently memory) leaks.
*
* We attempt to fix this by sending a 'terminator' event
* to the queue, after we've sent the CLOSED event. The
* terminator event causes the event-dispatching thread to
* self destruct.
*/
if (type == ConnectionEvent.CLOSED)
terminateQueue();
}
/**
* Return <code>getURLName.toString()</code> if this service has a URLName,
* otherwise it will return the default <code>toString</code>.
*/
public String toString() {
URLName url = getURLName();
if (url != null)
return url.toString();
else
return super.toString();
}
/*
* The queue of events to be delivered.
*/
private EventQueue q;
/*
* A lock for creating the EventQueue object. Only one thread should
* create an EventQueue for this service. We can't synchronize on the
* service's lock because that might violate the locking hierarchy in
* some cases.
*/
private Object qLock = new Object();
/**
* Add the event and vector of listeners to the queue to be delivered.
*/
protected void queueEvent(MailEvent event, Vector vector) {
// synchronize creation of the event queue
synchronized (qLock) {
if (q == null)
q = new EventQueue();
}
/*
* Copy the vector in order to freeze the state of the set
* of EventListeners the event should be delivered to prior
* to delivery. This ensures that any changes made to the
* Vector from a target listener's method during the delivery
* of this event will not take effect until after the event is
* delivered.
*/
Vector v = (Vector)vector.clone();
q.enqueue(event, v);
}
static class TerminatorEvent extends MailEvent {
private static final long serialVersionUID = 5542172141759168416L;
TerminatorEvent() {
super(new Object());
}
public void dispatch(Object listener) {
// Kill the event dispatching thread.
Thread.currentThread().interrupt();
}
}
// Dispatch the terminator
private void terminateQueue() {
synchronized (qLock) {
if (q != null) {
Vector dummyListeners = new Vector();
dummyListeners.setSize(1); // need atleast one listener
q.enqueue(new TerminatorEvent(), dummyListeners);
q = null;
}
}
}
/**
* Stop the event dispatcher thread so the queue can be garbage collected.
*/
protected void finalize() throws Throwable {
super.finalize();
terminateQueue();
}
}