org.deepsymmetry.beatlink

Class DeviceFinder

java.lang.Object

org.deepsymmetry.beatlink.DeviceFinder

public class DeviceFinder
extends Object

Watches for devices to report their presence by broadcasting announcement packets on port 50000, and keeps a list of the devices that have been seen, and the network address on which they were seen.

Author:

James Elliott

Field Summary

Fields

Modifier and Type	Field and Description
static int	ANNOUNCEMENT_PORT The port to which devices broadcast announcement messages to report their presence on the network.
static int	MAXIMUM_AGE The number of milliseconds after which we will consider a device to have disappeared if we have not received an announcement from it.

Method Summary

Modifier and Type	Method and Description
static void	addDeviceAnnouncementListener(DeviceAnnouncementListener listener) Adds the specified device announcement listener to receive device announcements when DJ Link devices are found on or leave the network.
static Set<DeviceAnnouncement>	currentDevices() Get the set of DJ Link devices which currently can be seen on the network.
static Set<DeviceAnnouncementListener>	getDeviceAnnouncementListeners() Get the set of device announcement listeners that are currently registered.
static DeviceAnnouncement	getLatestAnnouncementFrom(int deviceNumber) Find and return the device announcement that was most recently received from a device identifying itself with the specified device number, if any.
static boolean	isActive() Check whether we are presently listening for device announcements.
static void	removeDeviceAnnouncementListener(DeviceAnnouncementListener listener) Removes the specified device announcement listener so that it no longer receives device announcements when DJ Link devices are found on or leave the network.
static void	start() Start listening for device announcements and keeping track of the DJ Link devices visible on the network.
static void	stop() Stop listening for device announcements.

Methods inherited from class java.lang.Object

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

Field Detail

ANNOUNCEMENT_PORT

public static final int ANNOUNCEMENT_PORT

The port to which devices broadcast announcement messages to report their presence on the network.

See Also:

Constant Field Values

MAXIMUM_AGE

public static final int MAXIMUM_AGE

The number of milliseconds after which we will consider a device to have disappeared if we have not received an announcement from it.

See Also:

Constant Field Values

Method Detail

isActive

public static boolean isActive()

Check whether we are presently listening for device announcements.

Returns:

true if our socket is open and monitoring for DJ Link device announcements on the network

start

public static void start()
                  throws SocketException

Start listening for device announcements and keeping track of the DJ Link devices visible on the network. If already listening, has no effect.

Throws:

SocketException - if the socket to listen on port 50000 cannot be created

stop

public static void stop()

Stop listening for device announcements. Also discard any announcements which had been received, and notify any registered listeners that those devices have been lost.

currentDevices

public static Set<DeviceAnnouncement> currentDevices()

Get the set of DJ Link devices which currently can be seen on the network. These can be passed to VirtualCdj.getLatestStatusFor(DeviceUpdate) to find the current detailed status for that device, as long as the Virtual CDJ is active.

Returns:

the devices which have been heard from recently enough to be considered present on the network

Throws:

IllegalStateException - if the DeviceFinder is not active

getLatestAnnouncementFrom

public static DeviceAnnouncement getLatestAnnouncementFrom(int deviceNumber)

Find and return the device announcement that was most recently received from a device identifying itself with the specified device number, if any.

Parameters:

deviceNumber - the device number of interest

Returns:

the matching announcement or null if no such device has been heard from

addDeviceAnnouncementListener

public static void addDeviceAnnouncementListener(DeviceAnnouncementListener listener)

Adds the specified device announcement listener to receive device announcements when DJ Link devices are found on or leave the network. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

Device announcements are delivered to listeners on the Event Dispatch thread, so it is fine to interact with user interface objects in listener methods. Any code in the listener method must finish quickly, or unhandled events will back up and the user interface will be come unresponsive.

Parameters:

listener - the device announcement listener to add

removeDeviceAnnouncementListener

public static void removeDeviceAnnouncementListener(DeviceAnnouncementListener listener)

Removes the specified device announcement listener so that it no longer receives device announcements when DJ Link devices are found on or leave the network. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the device announcement listener to remove

getDeviceAnnouncementListeners

public static Set<DeviceAnnouncementListener> getDeviceAnnouncementListeners()

Get the set of device announcement listeners that are currently registered.

Returns:

the currently registered device announcement listeners