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JavaTM 2 Platform Std. Ed. v1.3.1 |
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javax.sound.midi
Class MidiMessage
java.lang.Object | +--javax.sound.midi.MidiMessage
- All Implemented Interfaces:
- Cloneable
- Direct Known Subclasses:
- MetaMessage, ShortMessage, SysexMessage
MidiMessage is the base class for MIDI messages. They include
not only the standard MIDI messages that a synthesizer can respond to, but also
"meta-events" that can be used by sequencer programs. There are meta-events
for such information as lyrics, copyrights, tempo indications, time and key
signatures, markers, etc. For more information, see the Standard MIDI Files 1.0
specification, which is part of the Complete MIDI 1.0 Detailed Specification
published by the MIDI Manufacturer's Association
(http://www.midi.org).
The base MidiMessage class provides access to three types of
information about a MIDI message:
- The messages's status byte
- The total length of the message in bytes (the status byte plus any data bytes)
- A byte array containing the complete message
MidiMessage includes methods to get, but not set, these values.
Setting them is a subclass responsibility.
The MIDI standard expresses MIDI data in bytes. However, because
JavaTM uses signed bytes, the Java Sound API uses integers
instead of bytes when expressing MIDI data. For example, the
getStatus() method of
MidiMessage returns MIDI status bytes as integers. If you are
processing MIDI data that originated outside Java Sound and now
is encoded as signed bytes, the bytes can
can be converted to integers using this conversion:
int i = (int)(byte & 0xFF)
If you simply need to pass a known MIDI byte value as a method parameter,
it can be expressed directly as an integer, using (for example) decimal or
hexidecimal notation. For instance, to pass the "active sensing" status byte
as the first argument to ShortMessage's
setMessage(int)
method, you can express it as 254 or 0xFE.
| Field Summary | |
protected byte[] |
data
The MIDI message data. |
protected int |
length
The number of bytes in the MIDI message, including the status byte and any data bytes. |
| Constructor Summary | |
protected |
MidiMessage(byte[] data)
Constructs a new MidiMessage. |
| Method Summary | |
abstract Object |
clone()
Creates a new object of the same class and with the same contents as this object. |
int |
getLength()
Obtains the total length of the MIDI message in bytes. |
byte[] |
getMessage()
Obtains the MIDI message data. |
int |
getStatus()
Obtains the status byte for the MIDI message. |
protected void |
setMessage(byte[] data,
int length)
Sets the data for the MIDI message. |
| Methods inherited from class java.lang.Object |
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
data
protected byte[] data
- The MIDI message data. The first byte is the status
byte for the message; subsequent bytes up to the length
of the message are data bytes for this message.
- See Also:
getLength()
length
protected int length
- The number of bytes in the MIDI message, including the
status byte and any data bytes.
- See Also:
getLength()
| Constructor Detail |
MidiMessage
protected MidiMessage(byte[] data)
- Constructs a new
MidiMessage. This protected constructor is called by concrete subclasses, which should ensure that the data array specifies a complete, valid MIDI message.- Parameters:
data- an array of bytes containing the complete message. The message data may be changed using thesetMessagemethod.- See Also:
setMessage(byte[], int)
| Method Detail |
setMessage
protected void setMessage(byte[] data,
int length)
throws InvalidMidiDataException
- Sets the data for the MIDI message. This protected
method is called by concrete subclasses, which should
ensure that the data array specifies a complete, valid MIDI
message.
getMessage
public byte[] getMessage()
- Obtains the MIDI message data. The first byte of the returned byte
array is the status byte of the message. Any subsequent bytes up to
the length of the message are data bytes. The byte array may have a
length which is greater than that of the actual message; the total
length of the message in bytes is reported by the
getLength()- Returns:
- the byte array containing the complete
MidiMessagedata
getStatus
public int getStatus()
- Obtains the status byte for the MIDI message. The status "byte" is
represented as an integer; see the
discussion in the
MidiMessageclass description.- Returns:
- the integer representation of this event's status byte
getLength
public int getLength()
- Obtains the total length of the MIDI message in bytes. A
MIDI message consists of one status byte and zero or more
data bytes. The return value ranges from 1 for system real-time messages,
to 2 or 3 for channel messages, to any value for meta and system
exclusive messages.
- Returns:
- the length of the message in bytes
clone
public abstract Object clone()
- Creates a new object of the same class and with the same contents
as this object.
- Returns:
- a clone of this instance.
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JavaTM 2 Platform Std. Ed. v1.3.1 |
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