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package javax.sound.midi;
import java.util.List;
MidiDevice is the base interface for all MIDI devices.
Common devices include synthesizers, sequencers, MIDI input ports, and MIDI
output ports.
A MidiDevice can be a transmitter or a receiver of MIDI events, or both. Therefore, it can provide Transmitter or Receiver instances (or both). Typically, MIDI IN ports provide transmitters, MIDI OUT ports and synthesizers provide receivers. A Sequencer typically provides transmitters for playback and receivers for recording.
A MidiDevice can be opened and closed explicitly as well as implicitly. Explicit opening is accomplished by calling open, explicit closing is done by calling close on the MidiDevice instance.
If an application opens a MidiDevice explicitly, it has to close it explicitly to free system resources and enable the application to exit cleanly. Implicit opening is done by calling
MidiSystem.getReceiver and
MidiSystem.getTransmitter. The MidiDevice used by
MidiSystem.getReceiver and
MidiSystem.getTransmitter is implementation-dependant
unless the properties javax.sound.midi.Receiver
and javax.sound.midi.Transmitter are used (see the description of properties to select default providers in MidiSystem). A MidiDevice
that was opened implicitly, is closed implicitly by closing the
Receiver or Transmitter that resulted in
opening it. If more than one implicitly opening
Receiver or Transmitter were obtained by
the application, the decive is closed after the last
Receiver or Transmitter has been
closed. On the other hand, calling getReceiver or
getTransmitter on the device instance directly does
not open the device implicitly. Closing these
Transmitters and Receivers does not close
the device implicitly. To use a device with Receivers
or Transmitters obtained this way, the device has to
be opened and closed explicitly.
If implicit and explicit opening and closing are mixed on the
same MidiDevice instance, the following rules apply:
- After an explicit open (either before or after implicit
opens), the device will not be closed by implicit closing. The only
way to close an explicitly opened device is an explicit close.
- An explicit close always closes the device, even if it also has
been opened implicitly. A subsequent implicit close has no further
effect.
To detect if a MidiDevice represents a hardware MIDI port, the
following programming technique can be used:
MidiDevice device = ...;
if ( ! (device instanceof Sequencer) && ! (device instanceof Synthesizer)) {
// we're now sure that device represents a MIDI port
// ...
}
A MidiDevice includes a Info
Author: Kara Kytle, Florian Bomers See Also:
/**
* <code>MidiDevice</code> is the base interface for all MIDI devices.
* Common devices include synthesizers, sequencers, MIDI input ports, and MIDI
* output ports.
*
* <p>A <code>MidiDevice</code> can be a transmitter or a receiver of
* MIDI events, or both. Therefore, it can provide {@link Transmitter}
* or {@link Receiver} instances (or both). Typically, MIDI IN ports
* provide transmitters, MIDI OUT ports and synthesizers provide
* receivers. A Sequencer typically provides transmitters for playback
* and receivers for recording.
*
* <p>A <code>MidiDevice</code> can be opened and closed explicitly as
* well as implicitly. Explicit opening is accomplished by calling
* {@link #open}, explicit closing is done by calling {@link
* #close} on the <code>MidiDevice</code> instance.
* If an application opens a <code>MidiDevice</code>
* explicitly, it has to close it explicitly to free system resources
* and enable the application to exit cleanly. Implicit opening is
* done by calling {@link javax.sound.midi.MidiSystem#getReceiver
* MidiSystem.getReceiver} and {@link
* javax.sound.midi.MidiSystem#getTransmitter
* MidiSystem.getTransmitter}. The <code>MidiDevice</code> used by
* <code>MidiSystem.getReceiver</code> and
* <code>MidiSystem.getTransmitter</code> is implementation-dependant
* unless the properties <code>javax.sound.midi.Receiver</code>
* and <code>javax.sound.midi.Transmitter</code> are used (see the
* description of properties to select default providers in
* {@link javax.sound.midi.MidiSystem}). A <code>MidiDevice</code>
* that was opened implicitly, is closed implicitly by closing the
* <code>Receiver</code> or <code>Transmitter</code> that resulted in
* opening it. If more than one implicitly opening
* <code>Receiver</code> or <code>Transmitter</code> were obtained by
* the application, the decive is closed after the last
* <code>Receiver</code> or <code>Transmitter</code> has been
* closed. On the other hand, calling <code>getReceiver</code> or
* <code>getTransmitter</code> on the device instance directly does
* not open the device implicitly. Closing these
* <code>Transmitter</code>s and <code>Receiver</code>s does not close
* the device implicitly. To use a device with <code>Receiver</code>s
* or <code>Transmitter</code>s obtained this way, the device has to
* be opened and closed explicitly.
*
* <p>If implicit and explicit opening and closing are mixed on the
* same <code>MidiDevice</code> instance, the following rules apply:
*
* <ul>
* <li>After an explicit open (either before or after implicit
* opens), the device will not be closed by implicit closing. The only
* way to close an explicitly opened device is an explicit close.</li>
*
* <li>An explicit close always closes the device, even if it also has
* been opened implicitly. A subsequent implicit close has no further
* effect.</li>
* </ul>
*
* To detect if a MidiDevice represents a hardware MIDI port, the
* following programming technique can be used:
*
* <pre>
* MidiDevice device = ...;
* if ( ! (device instanceof Sequencer) && ! (device instanceof Synthesizer)) {
* // we're now sure that device represents a MIDI port
* // ...
* }
* </pre>
*
* <p>
* A <code>MidiDevice</code> includes a <code>{@link MidiDevice.Info}</code> object
* to provide manufacturer information and so on.
*
* @see Synthesizer
* @see Sequencer
* @see Receiver
* @see Transmitter
*
* @author Kara Kytle
* @author Florian Bomers
*/
public interface MidiDevice {
Obtains information about the device, including its Java class and
Strings containing its name, vendor, and description.
Returns: device info
/**
* Obtains information about the device, including its Java class and
* <code>Strings</code> containing its name, vendor, and description.
*
* @return device info
*/
public Info getDeviceInfo();
Opens the device, indicating that it should now acquire any
system resources it requires and become operational.
An application opening a device explicitly with this call has to close the device by calling close. This is necessary to release system resources and allow applications to exit cleanly.
Note that some devices, once closed, cannot be reopened. Attempts
to reopen such a device will always result in a MidiUnavailableException.
Throws: - MidiUnavailableException – thrown if the device cannot be
opened due to resource restrictions.
- SecurityException – thrown if the device cannot be
opened due to security restrictions.
See Also:
/**
* Opens the device, indicating that it should now acquire any
* system resources it requires and become operational.
*
* <p>An application opening a device explicitly with this call
* has to close the device by calling {@link #close}. This is
* necessary to release system resources and allow applications to
* exit cleanly.
*
* <p>
* Note that some devices, once closed, cannot be reopened. Attempts
* to reopen such a device will always result in a MidiUnavailableException.
*
* @throws MidiUnavailableException thrown if the device cannot be
* opened due to resource restrictions.
* @throws SecurityException thrown if the device cannot be
* opened due to security restrictions.
*
* @see #close
* @see #isOpen
*/
public void open() throws MidiUnavailableException;
Closes the device, indicating that the device should now release
any system resources it is using.
All Receiver and Transmitter instances
open from this device are closed. This includes instances retrieved
via MidiSystem.
See Also: - open
- isOpen
/**
* Closes the device, indicating that the device should now release
* any system resources it is using.
*
* <p>All <code>Receiver</code> and <code>Transmitter</code> instances
* open from this device are closed. This includes instances retrieved
* via <code>MidiSystem</code>.
*
* @see #open
* @see #isOpen
*/
public void close();
Reports whether the device is open.
See Also: Returns: true if the device is open, otherwise
false
/**
* Reports whether the device is open.
*
* @return <code>true</code> if the device is open, otherwise
* <code>false</code>
* @see #open
* @see #close
*/
public boolean isOpen();
Obtains the current time-stamp of the device, in microseconds.
If a device supports time-stamps, it should start counting at
0 when the device is opened and continue incrementing its
time-stamp in microseconds until the device is closed.
If it does not support time-stamps, it should always return
-1.
Returns: the current time-stamp of the device in microseconds,
or -1 if time-stamping is not supported by the device.
/**
* Obtains the current time-stamp of the device, in microseconds.
* If a device supports time-stamps, it should start counting at
* 0 when the device is opened and continue incrementing its
* time-stamp in microseconds until the device is closed.
* If it does not support time-stamps, it should always return
* -1.
* @return the current time-stamp of the device in microseconds,
* or -1 if time-stamping is not supported by the device.
*/
public long getMicrosecondPosition();
Obtains the maximum number of MIDI IN connections available on this
MIDI device for receiving MIDI data.
Returns: maximum number of MIDI IN connections,
or -1 if an unlimited number of connections is available.
/**
* Obtains the maximum number of MIDI IN connections available on this
* MIDI device for receiving MIDI data.
* @return maximum number of MIDI IN connections,
* or -1 if an unlimited number of connections is available.
*/
public int getMaxReceivers();
Obtains the maximum number of MIDI OUT connections available on this
MIDI device for transmitting MIDI data.
Returns: maximum number of MIDI OUT connections,
or -1 if an unlimited number of connections is available.
/**
* Obtains the maximum number of MIDI OUT connections available on this
* MIDI device for transmitting MIDI data.
* @return maximum number of MIDI OUT connections,
* or -1 if an unlimited number of connections is available.
*/
public int getMaxTransmitters();
Obtains a MIDI IN receiver through which the MIDI device may receive
MIDI data. The returned receiver must be closed when the application
has finished using it.
Obtaining a Receiver with this method does not open the device. To be able to use the device, it has to be opened explicitly by calling open. Also, closing the Receiver does not close the device. It has to be closed explicitly by calling close.
Throws: - MidiUnavailableException – thrown if a receiver is not available
due to resource restrictions
See Also: Returns: a receiver for the device.
/**
* Obtains a MIDI IN receiver through which the MIDI device may receive
* MIDI data. The returned receiver must be closed when the application
* has finished using it.
*
* <p>Obtaining a <code>Receiver</code> with this method does not
* open the device. To be able to use the device, it has to be
* opened explicitly by calling {@link #open}. Also, closing the
* <code>Receiver</code> does not close the device. It has to be
* closed explicitly by calling {@link #close}.
*
* @return a receiver for the device.
* @throws MidiUnavailableException thrown if a receiver is not available
* due to resource restrictions
* @see Receiver#close()
*/
public Receiver getReceiver() throws MidiUnavailableException;
Returns all currently active, non-closed receivers
connected with this MidiDevice.
A receiver can be removed
from the device by closing it.
Returns: an unmodifiable list of the open receivers Since: 1.5
/**
* Returns all currently active, non-closed receivers
* connected with this MidiDevice.
* A receiver can be removed
* from the device by closing it.
* @return an unmodifiable list of the open receivers
* @since 1.5
*/
List<Receiver> getReceivers();
Obtains a MIDI OUT connection from which the MIDI device will transmit
MIDI data The returned transmitter must be closed when the application
has finished using it.
Obtaining a Transmitter with this method does not open the device. To be able to use the device, it has to be opened explicitly by calling open. Also, closing the Transmitter does not close the device. It has to be closed explicitly by calling close.
Throws: - MidiUnavailableException – thrown if a transmitter is not available
due to resource restrictions
See Also: Returns: a MIDI OUT transmitter for the device.
/**
* Obtains a MIDI OUT connection from which the MIDI device will transmit
* MIDI data The returned transmitter must be closed when the application
* has finished using it.
*
* <p>Obtaining a <code>Transmitter</code> with this method does not
* open the device. To be able to use the device, it has to be
* opened explicitly by calling {@link #open}. Also, closing the
* <code>Transmitter</code> does not close the device. It has to be
* closed explicitly by calling {@link #close}.
*
* @return a MIDI OUT transmitter for the device.
* @throws MidiUnavailableException thrown if a transmitter is not available
* due to resource restrictions
* @see Transmitter#close()
*/
public Transmitter getTransmitter() throws MidiUnavailableException;
Returns all currently active, non-closed transmitters
connected with this MidiDevice.
A transmitter can be removed
from the device by closing it.
Returns: an unmodifiable list of the open transmitters Since: 1.5
/**
* Returns all currently active, non-closed transmitters
* connected with this MidiDevice.
* A transmitter can be removed
* from the device by closing it.
* @return an unmodifiable list of the open transmitters
* @since 1.5
*/
List<Transmitter> getTransmitters();
A MidiDevice.Info object contains assorted
data about a MidiDeviceSee Also:
/**
* A <code>MidiDevice.Info</code> object contains assorted
* data about a <code>{@link MidiDevice}</code>, including its
* name, the company who created it, and descriptive text.
*
* @see MidiDevice#getDeviceInfo
*/
public static class Info {
The device's name.
/**
* The device's name.
*/
private String name;
The name of the company who provides the device.
/**
* The name of the company who provides the device.
*/
private String vendor;
A description of the device.
/**
* A description of the device.
*/
private String description;
Device version.
/**
* Device version.
*/
private String version;
Constructs a device info object.
Params: - name – the name of the device
- vendor – the name of the company who provides the device
- description – a description of the device
- version – version information for the device
/**
* Constructs a device info object.
*
* @param name the name of the device
* @param vendor the name of the company who provides the device
* @param description a description of the device
* @param version version information for the device
*/
protected Info(String name, String vendor, String description, String version) {
this.name = name;
this.vendor = vendor;
this.description = description;
this.version = version;
}
Reports whether two objects are equal.
Returns true if the objects are identical.
Params: - obj – the reference object with which to compare this
object
Returns: true if this object is the same as the
obj argument; false otherwise
/**
* Reports whether two objects are equal.
* Returns <code>true</code> if the objects are identical.
* @param obj the reference object with which to compare this
* object
* @return <code>true</code> if this object is the same as the
* <code>obj</code> argument; <code>false</code> otherwise
*/
public final boolean equals(Object obj) {
return super.equals(obj);
}
Finalizes the hashcode method.
/**
* Finalizes the hashcode method.
*/
public final int hashCode() {
return super.hashCode();
}
Obtains the name of the device.
Returns: a string containing the device's name
/**
* Obtains the name of the device.
*
* @return a string containing the device's name
*/
public final String getName() {
return name;
}
Obtains the name of the company who supplies the device.
Returns: device the vendor's name
/**
* Obtains the name of the company who supplies the device.
* @return device the vendor's name
*/
public final String getVendor() {
return vendor;
}
Obtains the description of the device.
Returns: a description of the device
/**
* Obtains the description of the device.
* @return a description of the device
*/
public final String getDescription() {
return description;
}
Obtains the version of the device.
Returns: textual version information for the device.
/**
* Obtains the version of the device.
* @return textual version information for the device.
*/
public final String getVersion() {
return version;
}
Provides a string representation of the device information.
Returns: a description of the info object
/**
* Provides a string representation of the device information.
* @return a description of the info object
*/
public final String toString() {
return name;
}
} // class Info
}