public class MidiSystem extends Object
The MidiSystem
class provides access to the installed MIDI system resources, including devices such as synthesizers, sequencers, and MIDI input and output ports. A typical simple MIDI application might begin by invoking one or more MidiSystem
methods to learn what devices are installed and to obtain the ones needed in that application.
The class also has methods for reading files, streams, and URLs that contain standard MIDI file data or soundbanks. You can query the MidiSystem
for the format of a specified MIDI file.
You cannot instantiate a MidiSystem
; all the methods are static.
Properties can be used to specify default MIDI devices. Both system properties and a properties file are considered. The sound.properties
properties file is read from an implementation-specific location (typically it is the lib
directory in the Java installation directory). If a property exists both as a system property and in the properties file, the system property takes precedence. If none is specified, a suitable default is chosen among the available devices. The syntax of the properties file is specified in Properties.load
. The following table lists the available property keys and which methods consider them:
Property Key | Interface | Affected Method |
---|---|---|
javax.sound.midi.Receiver | Receiver | getReceiver() |
javax.sound.midi.Sequencer | Sequencer | getSequencer() |
javax.sound.midi.Synthesizer | Synthesizer | getSynthesizer() |
javax.sound.midi.Transmitter | Transmitter | getTransmitter() |
MIDI device provider
class. The device name is matched against the String
returned by the getName
method of MidiDevice.Info
. Either the class name, or the device name may be omitted. If only the class name is specified, the trailing hash mark is optional. If the provider class is specified, and it can be successfully retrieved from the installed providers, the list of MidiDevice.Info
objects is retrieved from the provider. Otherwise, or when these devices do not provide a subsequent match, the list is retrieved from getMidiDeviceInfo()
to contain all available MidiDevice.Info
objects.
If a device name is specified, the resulting list of MidiDevice.Info
objects is searched: the first one with a matching name, and whose MidiDevice
implements the respective interface, will be returned. If no matching MidiDevice.Info
object is found, or the device name is not specified, the first suitable device from the resulting list will be returned. For Sequencer and Synthesizer, a device is suitable if it implements the respective interface; whereas for Receiver and Transmitter, a device is suitable if it implements neither Sequencer nor Synthesizer and provides at least one Receiver or Transmitter, respectively. For example, the property javax.sound.midi.Receiver
with a value "com.sun.media.sound.MidiProvider#SunMIDI1"
will have the following consequences when getReceiver
is called: if the class com.sun.media.sound.MidiProvider
exists in the list of installed MIDI device providers, the first Receiver
device with name "SunMIDI1"
will be returned. If it cannot be found, the first Receiver
from that provider will be returned, regardless of name. If there is none, the first Receiver
with name "SunMIDI1"
in the list of all devices (as returned by getMidiDeviceInfo
) will be returned, or, if not found, the first Receiver
that can be found in the list of all devices is returned. If that fails, too, a MidiUnavailableException
is thrown.
public static MidiDevice.Info[] getMidiDeviceInfo()
Obtains an array of information objects representing the set of all MIDI devices available on the system. A returned information object can then be used to obtain the corresponding device object, by invoking getMidiDevice
.
MidiDevice.Info
objects, one for each installed MIDI device. If no such devices are installed, an array of length 0 is returned.public static MidiDevice getMidiDevice(MidiDevice.Info info) throws MidiUnavailableException
Obtains the requested MIDI device.
info
- a device information object representing the desired device.MidiUnavailableException
- if the requested device is not available due to resource restrictionsIllegalArgumentException
- if the info object does not represent a MIDI device installed on the systemgetMidiDeviceInfo()
public static Receiver getReceiver() throws MidiUnavailableException
Obtains a MIDI receiver from an external MIDI port or other default device. The returned receiver always implements the MidiDeviceReceiver
interface.
If the system property javax.sound.midi.Receiver
is defined or it is defined in the file "sound.properties", it is used to identify the device that provides the default receiver. For details, refer to the class description
. If a suitable MIDI port is not available, the Receiver is retrieved from an installed synthesizer.
If a native receiver provided by the default device does not implement the MidiDeviceReceiver
interface, it will be wrapped in a wrapper class that implements the MidiDeviceReceiver
interface. The corresponding Receiver
method calls will be forwarded to the native receiver.
If this method returns successfully, the MidiDevice
the Receiver
belongs to is opened implicitly, if it is not already open. It is possible to close an implicitly opened device by calling close
on the returned Receiver
. All open Receiver
instances have to be closed in order to release system resources hold by the MidiDevice
. For a detailed description of open/close behaviour see the class description of MidiDevice
.
MidiUnavailableException
- if the default receiver is not available due to resource restrictions, or no device providing receivers is installed in the systempublic static Transmitter getTransmitter() throws MidiUnavailableException
Obtains a MIDI transmitter from an external MIDI port or other default source. The returned transmitter always implements the MidiDeviceTransmitter
interface.
If the system property javax.sound.midi.Transmitter
is defined or it is defined in the file "sound.properties", it is used to identify the device that provides the default transmitter. For details, refer to the class description
.
If a native transmitter provided by the default device does not implement the MidiDeviceTransmitter
interface, it will be wrapped in a wrapper class that implements the MidiDeviceTransmitter
interface. The corresponding Transmitter
method calls will be forwarded to the native transmitter.
If this method returns successfully, the MidiDevice
the Transmitter
belongs to is opened implicitly, if it is not already open. It is possible to close an implicitly opened device by calling close
on the returned Transmitter
. All open Transmitter
instances have to be closed in order to release system resources hold by the MidiDevice
. For a detailed description of open/close behaviour see the class description of MidiDevice
.
MidiUnavailableException
- if the default transmitter is not available due to resource restrictions, or no device providing transmitters is installed in the systempublic static Synthesizer getSynthesizer() throws MidiUnavailableException
Obtains the default synthesizer.
If the system property javax.sound.midi.Synthesizer
is defined or it is defined in the file "sound.properties", it is used to identify the default synthesizer. For details, refer to the class description
.
MidiUnavailableException
- if the synthesizer is not available due to resource restrictions, or no synthesizer is installed in the systempublic static Sequencer getSequencer() throws MidiUnavailableException
Obtains the default Sequencer
, connected to a default device. The returned Sequencer
instance is connected to the default Synthesizer
, as returned by getSynthesizer()
. If there is no Synthesizer
available, or the default Synthesizer
cannot be opened, the sequencer
is connected to the default Receiver
, as returned by getReceiver()
. The connection is made by retrieving a Transmitter
instance from the Sequencer
and setting its Receiver
. Closing and re-opening the sequencer will restore the connection to the default device.
This method is equivalent to calling getSequencer(true)
.
If the system property javax.sound.midi.Sequencer
is defined or it is defined in the file "sound.properties", it is used to identify the default sequencer. For details, refer to the class description
.
MidiUnavailableException
- if the sequencer is not available due to resource restrictions, or there is no Receiver
available by any installed MidiDevice
, or no sequencer is installed in the system.getSequencer(boolean)
, getSynthesizer()
, getReceiver()
public static Sequencer getSequencer(boolean connected) throws MidiUnavailableException
Obtains the default Sequencer
, optionally connected to a default device.
If connected
is true, the returned Sequencer
instance is connected to the default Synthesizer
, as returned by getSynthesizer()
. If there is no Synthesizer
available, or the default Synthesizer
cannot be opened, the sequencer
is connected to the default Receiver
, as returned by getReceiver()
. The connection is made by retrieving a Transmitter
instance from the Sequencer
and setting its Receiver
. Closing and re-opening the sequencer will restore the connection to the default device.
If connected
is false, the returned Sequencer
instance is not connected, it has no open Transmitters
. In order to play the sequencer on a MIDI device, or a Synthesizer
, it is necessary to get a Transmitter
and set its Receiver
.
If the system property javax.sound.midi.Sequencer
is defined or it is defined in the file "sound.properties", it is used to identify the default sequencer. For details, refer to the class description
.
connected
- whether or not the returned Sequencer
is connected to the default Synthesizer
MidiUnavailableException
- if the sequencer is not available due to resource restrictions, or no sequencer is installed in the system, or if connected
is true, and there is no Receiver
available by any installed MidiDevice
getSynthesizer()
, getReceiver()
public static Soundbank getSoundbank(InputStream stream) throws InvalidMidiDataException, IOException
Constructs a MIDI sound bank by reading it from the specified stream. The stream must point to a valid MIDI soundbank file. In general, MIDI soundbank providers may need to read some data from the stream before determining whether they support it. These parsers must be able to mark the stream, read enough data to determine whether they support the stream, and, if not, reset the stream's read pointer to its original position. If the input stream does not support this, this method may fail with an IOException.
stream
- the source of the sound bank data.InvalidMidiDataException
- if the stream does not point to valid MIDI soundbank data recognized by the systemIOException
- if an I/O error occurred when loading the soundbankInputStream.markSupported()
, InputStream.mark(int)
public static Soundbank getSoundbank(URL url) throws InvalidMidiDataException, IOException
Constructs a Soundbank
by reading it from the specified URL. The URL must point to a valid MIDI soundbank file.
url
- the source of the sound bank dataInvalidMidiDataException
- if the URL does not point to valid MIDI soundbank data recognized by the systemIOException
- if an I/O error occurred when loading the soundbankpublic static Soundbank getSoundbank(File file) throws InvalidMidiDataException, IOException
Constructs a Soundbank
by reading it from the specified File
. The File
must point to a valid MIDI soundbank file.
file
- the source of the sound bank dataInvalidMidiDataException
- if the File
does not point to valid MIDI soundbank data recognized by the systemIOException
- if an I/O error occurred when loading the soundbankpublic static MidiFileFormat getMidiFileFormat(InputStream stream) throws InvalidMidiDataException, IOException
Obtains the MIDI file format of the data in the specified input stream. The stream must point to valid MIDI file data for a file type recognized by the system.
This method and/or the code it invokes may need to read some data from the stream to determine whether its data format is supported. The implementation may therefore need to mark the stream, read enough data to determine whether it is in a supported format, and reset the stream's read pointer to its original position. If the input stream does not permit this set of operations, this method may fail with an IOException
.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while determining the file format.
stream
- the input stream from which file format information should be extractedMidiFileFormat
object describing the MIDI file formatInvalidMidiDataException
- if the stream does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurs while accessing the streamgetMidiFileFormat(URL)
, getMidiFileFormat(File)
, InputStream.markSupported()
, InputStream.mark(int)
public static MidiFileFormat getMidiFileFormat(URL url) throws InvalidMidiDataException, IOException
Obtains the MIDI file format of the data in the specified URL. The URL must point to valid MIDI file data for a file type recognized by the system.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while determining the file format.
url
- the URL from which file format information should be extractedMidiFileFormat
object describing the MIDI file formatInvalidMidiDataException
- if the URL does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurs while accessing the URLgetMidiFileFormat(InputStream)
, getMidiFileFormat(File)
public static MidiFileFormat getMidiFileFormat(File file) throws InvalidMidiDataException, IOException
Obtains the MIDI file format of the specified File
. The File
must point to valid MIDI file data for a file type recognized by the system.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while determining the file format.
file
- the File
from which file format information should be extractedMidiFileFormat
object describing the MIDI file formatInvalidMidiDataException
- if the File
does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurs while accessing the filegetMidiFileFormat(InputStream)
, getMidiFileFormat(URL)
public static Sequence getSequence(InputStream stream) throws InvalidMidiDataException, IOException
Obtains a MIDI sequence from the specified input stream. The stream must point to valid MIDI file data for a file type recognized by the system.
This method and/or the code it invokes may need to read some data from the stream to determine whether its data format is supported. The implementation may therefore need to mark the stream, read enough data to determine whether it is in a supported format, and reset the stream's read pointer to its original position. If the input stream does not permit this set of operations, this method may fail with an IOException
.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while constructing the Sequence
object from the file data.
stream
- the input stream from which the Sequence
should be constructedSequence
object based on the MIDI file data contained in the input streamInvalidMidiDataException
- if the stream does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurs while accessing the streamInputStream.markSupported()
, InputStream.mark(int)
public static Sequence getSequence(URL url) throws InvalidMidiDataException, IOException
Obtains a MIDI sequence from the specified URL. The URL must point to valid MIDI file data for a file type recognized by the system.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while constructing the Sequence
object from the file data.
url
- the URL from which the Sequence
should be constructedSequence
object based on the MIDI file data pointed to by the URLInvalidMidiDataException
- if the URL does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurs while accessing the URLpublic static Sequence getSequence(File file) throws InvalidMidiDataException, IOException
Obtains a MIDI sequence from the specified File
. The File
must point to valid MIDI file data for a file type recognized by the system.
This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while constructing the Sequence
object from the file data.
file
- the File
from which the Sequence
should be constructedSequence
object based on the MIDI file data pointed to by the FileInvalidMidiDataException
- if the File does not point to valid MIDI file data recognized by the systemIOException
- if an I/O exception occurspublic static int[] getMidiFileTypes()
Obtains the set of MIDI file types for which file writing support is provided by the system.
public static boolean isFileTypeSupported(int fileType)
Indicates whether file writing support for the specified MIDI file type is provided by the system.
fileType
- the file type for which write capabilities are queriedtrue
if the file type is supported, otherwise false
public static int[] getMidiFileTypes(Sequence sequence)
Obtains the set of MIDI file types that the system can write from the sequence specified.
sequence
- the sequence for which MIDI file type support is queriedpublic static boolean isFileTypeSupported(int fileType, Sequence sequence)
Indicates whether a MIDI file of the file type specified can be written from the sequence indicated.
fileType
- the file type for which write capabilities are queriedsequence
- the sequence for which file writing support is queriedtrue
if the file type is supported for this sequence, otherwise false
public static int write(Sequence in, int fileType, OutputStream out) throws IOException
Writes a stream of bytes representing a file of the MIDI file type indicated to the output stream provided.
in
- sequence containing MIDI data to be written to the filefileType
- the file type of the file to be written to the output streamout
- stream to which the file data should be writtenIOException
- if an I/O exception occursIllegalArgumentException
- if the file format is not supported by the systemisFileTypeSupported(int, Sequence)
, getMidiFileTypes(Sequence)
public static int write(Sequence in, int type, File out) throws IOException
Writes a stream of bytes representing a file of the MIDI file type indicated to the external file provided.
in
- sequence containing MIDI data to be written to the filetype
- the file type of the file to be written to the output streamout
- external file to which the file data should be writtenIOException
- if an I/O exception occursIllegalArgumentException
- if the file type is not supported by the systemisFileTypeSupported(int, Sequence)
, getMidiFileTypes(Sequence)
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