Java tutorial
/* * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sound.midi; import com.sun.media.sound.MidiUtils; /** * A {@code SysexMessage} object represents a MIDI system exclusive message. * <p> * When a system exclusive message is read from a MIDI file, it always has a * defined length. Data from a system exclusive message from a MIDI file should * be stored in the data array of a {@code SysexMessage} as follows: the system * exclusive message status byte (0xF0 or 0xF7), all message data bytes, and * finally the end-of-exclusive flag (0xF7). The length reported by the * {@code SysexMessage} object is therefore the length of the system exclusive * data plus two: one byte for the status byte and one for the end-of-exclusive * flag. * <p> * As dictated by the Standard MIDI Files specification, two status byte values * are legal for a {@code SysexMessage} read from a MIDI file: * <ul> * <li>0xF0: System Exclusive message (same as in MIDI wire protocol) * <li>0xF7: Special System Exclusive message * </ul> * When Java Sound is used to handle system exclusive data that is being * received using MIDI wire protocol, it should place the data in one or more * {@code SysexMessages}. In this case, the length of the system exclusive data * is not known in advance; the end of the system exclusive data is marked by an * end-of-exclusive flag (0xF7) in the MIDI wire byte stream. * <ul> * <li>0xF0: System Exclusive message (same as in MIDI wire protocol) * <li>0xF7: End of Exclusive (EOX) * </ul> * The first {@code SysexMessage} object containing data for a particular system * exclusive message should have the status value 0xF0. If this message contains * all the system exclusive data for the message, it should end with the status * byte 0xF7 (EOX). Otherwise, additional system exclusive data should be sent * in one or more {@code SysexMessages} with a status value of 0xF7. The * {@code SysexMessage} containing the last of the data for the system exclusive * message should end with the value 0xF7 (EOX) to mark the end of the system * exclusive message. * <p> * If system exclusive data from {@code SysexMessages} objects is being * transmitted using MIDI wire protocol, only the initial 0xF0 status byte, the * system exclusive data itself, and the final 0xF7 (EOX) byte should be * propagated; any 0xF7 status bytes used to indicate that a * {@code SysexMessage} contains continuing system exclusive data should not be * propagated via MIDI wire protocol. * * @author David Rivas * @author Kara Kytle * @author Florian Bomers */ public class SysexMessage extends MidiMessage { // Status byte defines /** * Status byte for System Exclusive message (0xF0, or 240). * * @see MidiMessage#getStatus */ public static final int SYSTEM_EXCLUSIVE = 0xF0; // 240 /** * Status byte for Special System Exclusive message (0xF7, or 247), which is * used in MIDI files. It has the same value as END_OF_EXCLUSIVE, which is * used in the real-time "MIDI wire" protocol. * * @see MidiMessage#getStatus */ public static final int SPECIAL_SYSTEM_EXCLUSIVE = 0xF7; // 247 /** * The data bytes for this system exclusive message. These are initialized * to {@code null} and are set explicitly by * {@link #setMessage(int, byte[], int, long) setMessage}. */ //protected byte[] data = null; /** * Constructs a new {@code SysexMessage}. The contents of the new message * are guaranteed to specify a valid MIDI message. Subsequently, you may set * the contents of the message using one of the {@code setMessage} methods. * * @see #setMessage */ public SysexMessage() { this(new byte[2]); // Default sysex message data: SOX followed by EOX data[0] = (byte) (SYSTEM_EXCLUSIVE & 0xFF); data[1] = (byte) (ShortMessage.END_OF_EXCLUSIVE & 0xFF); } /** * Constructs a new {@code SysexMessage} and sets the data for the message. * The first byte of the data array must be a valid system exclusive status * byte (0xF0 or 0xF7). The contents of the message can be changed by using * one of the {@code setMessage} methods. * * @param data the system exclusive message data including the status byte * @param length the length of the valid message data in the array, * including the status byte; it should be non-negative and less * than or equal to {@code data.length} * @throws InvalidMidiDataException if the parameter values do not specify a * valid MIDI meta message * @see #setMessage(byte[], int) * @see #setMessage(int, byte[], int) * @see #getData() * @since 1.7 */ public SysexMessage(byte[] data, int length) throws InvalidMidiDataException { super(null); setMessage(data, length); } /** * Constructs a new {@code SysexMessage} and sets the data for the message. * The contents of the message can be changed by using one of the * {@code setMessage} methods. * * @param status the status byte for the message; it must be a valid system * exclusive status byte (0xF0 or 0xF7) * @param data the system exclusive message data (without the status byte) * @param length the length of the valid message data in the array; it * should be non-negative and less than or equal to * {@code data.length} * @throws InvalidMidiDataException if the parameter values do not specify a * valid MIDI system exclusive message * @see #setMessage(byte[], int) * @see #setMessage(int, byte[], int) * @see #getData() * @since 1.7 */ public SysexMessage(int status, byte[] data, int length) throws InvalidMidiDataException { super(null); setMessage(status, data, length); } /** * Constructs a new {@code SysexMessage}. * * @param data an array of bytes containing the complete message. The * message data may be changed using the {@code setMessage} method. * @see #setMessage */ protected SysexMessage(byte[] data) { super(data); } /** * Sets the data for the system exclusive message. The first byte of the * data array must be a valid system exclusive status byte (0xF0 or 0xF7). * * @param data the system exclusive message data * @param length the length of the valid message data in the array, * including the status byte * @throws InvalidMidiDataException if the parameter values do not specify a * valid MIDI system exclusive message */ @Override public void setMessage(byte[] data, int length) throws InvalidMidiDataException { MidiUtils.checkSysexStatus(data, length); super.setMessage(data, length); } /** * Sets the data for the system exclusive message. * * @param status the status byte for the message (0xF0 or 0xF7) * @param data the system exclusive message data * @param length the length of the valid message data in the array * @throws InvalidMidiDataException if the status byte is invalid for a * system exclusive message */ public void setMessage(int status, byte[] data, int length) throws InvalidMidiDataException { MidiUtils.checkSysexStatus(status); if (length < 0 || length > data.length) { throw new IndexOutOfBoundsException("length out of bounds: " + length); } this.length = length + 1; if (this.data == null || this.data.length < this.length) { this.data = new byte[this.length]; } this.data[0] = (byte) (status & 0xFF); if (length > 0) { System.arraycopy(data, 0, this.data, 1, length); } } /** * Obtains a copy of the data for the system exclusive message. The returned * array of bytes does not include the status byte. * * @return array containing the system exclusive message data */ public byte[] getData() { byte[] returnedArray = new byte[length - 1]; System.arraycopy(data, 1, returnedArray, 0, (length - 1)); return returnedArray; } /** * Creates a new object of the same class and with the same contents as this * object. * * @return a clone of this instance */ @Override public Object clone() { byte[] newData = new byte[length]; System.arraycopy(data, 0, newData, 0, newData.length); return new SysexMessage(newData); } }