Java example source code file (SysexMessage.java)

This example Java source code file (SysexMessage.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

indexoutofboundsexception, invalid, invalidmididataexception, midimessage, object, special_system_exclusive, sysexmessage, system_exclusive

The SysexMessage.java Java example source code

/*
 * Copyright (c) 1998, 2013, 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;

/**
 * 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>
 * <p>
 * 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 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


    // Instance variables


    /*
     * 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 meta 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.
     */
    public void setMessage(byte[] data, int length) throws InvalidMidiDataException {
        int status = (data[0] & 0xFF);
        if ((status != 0xF0) && (status != 0xF7)) {
            throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
        }
        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 sysex message
     */
    public void setMessage(int status, byte[] data, int length) throws InvalidMidiDataException {
        if ( (status != 0xF0) && (status != 0xF7) ) {
            throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(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
     */
    public Object clone() {
        byte[] newData = new byte[length];
        System.arraycopy(data, 0, newData, 0, newData.length);
        SysexMessage event = new SysexMessage(newData);
        return event;
    }
}