JDK8/Java8源码在线阅读

/*
 * Copyright (c) 1999, 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
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 */

package com.sun.media.sound;

import javax.sound.midi.*;



/**
 * MidiInDevice class representing functionality of MidiIn devices.
 *
 * @author David Rivas
 * @author Kara Kytle
 * @author Florian Bomers
 */
final class MidiInDevice extends AbstractMidiDevice implements Runnable {

    private Thread midiInThread = null;

    // CONSTRUCTOR

    MidiInDevice(AbstractMidiDeviceProvider.Info info) {
        super(info);
        if(Printer.trace) Printer.trace("MidiInDevice CONSTRUCTOR");
    }


    // IMPLEMENTATION OF ABSTRACT MIDI DEVICE METHODS

    // $$kk: 06.24.99: i have this both opening and starting the midi in device.
    // may want to separate these??
    protected synchronized void implOpen() throws MidiUnavailableException {
        if (Printer.trace) Printer.trace("> MidiInDevice: implOpen()");

        int index = ((MidiInDeviceProvider.MidiInDeviceInfo)getDeviceInfo()).getIndex();
        id = nOpen(index); // can throw MidiUnavailableException

        if (id == 0) {
            throw new MidiUnavailableException("Unable to open native device");
        }

        // create / start a thread to get messages
        if (midiInThread == null) {
            midiInThread = JSSecurityManager.createThread(this,
                                                    "Java Sound MidiInDevice Thread",   // name
                                                    false,  // daemon
                                                    -1,    // priority
                                                    true); // doStart
        }

        nStart(id); // can throw MidiUnavailableException
        if (Printer.trace) Printer.trace("< MidiInDevice: implOpen() completed");
    }


    // $$kk: 06.24.99: i have this both stopping and closing the midi in device.
    // may want to separate these??
    protected synchronized void implClose() {
        if (Printer.trace) Printer.trace("> MidiInDevice: implClose()");
        long oldId = id;
        id = 0;

        super.implClose();

        // close the device
        nStop(oldId);
        if (midiInThread != null) {
            try {
                midiInThread.join(1000);
            } catch (InterruptedException e) {
                // IGNORE EXCEPTION
            }
        }
        nClose(oldId);
        if (Printer.trace) Printer.trace("< MidiInDevice: implClose() completed");
    }


    public long getMicrosecondPosition() {
        long timestamp = -1;
        if (isOpen()) {
            timestamp = nGetTimeStamp(id);
        }
        return timestamp;
    }


    // OVERRIDES OF ABSTRACT MIDI DEVICE METHODS


    protected boolean hasTransmitters() {
        return true;
    }


    protected Transmitter createTransmitter() {
        return new MidiInTransmitter();
    }

    /**
      * An own class to distinguish the class name from
      * the transmitter of other devices
      */
    private final class MidiInTransmitter extends BasicTransmitter {
        private MidiInTransmitter() {
            super();
        }
    }

    // RUNNABLE METHOD

    public void run() {
        // while the device is started, keep trying to get messages.
        // this thread returns from native code whenever stop() or close() is called
        while (id!=0) {
            // go into native code and retrieve messages
            nGetMessages(id);
            if (id!=0) {
                try {
                    Thread.sleep(1);
                } catch (InterruptedException e) {}
            }
        }
        if(Printer.verbose) Printer.verbose("MidiInDevice Thread exit");
        // let the thread exit
        midiInThread = null;
    }


    // CALLBACKS FROM NATIVE

    /**
     * Callback from native code when a short MIDI event is received from hardware.
     * @param packedMsg: status | data1 << 8 | data2 << 8
     * @param timeStamp time-stamp in microseconds
     */
    void callbackShortMessage(int packedMsg, long timeStamp) {
        if (packedMsg == 0 || id == 0) {
            return;
        }

        /*if(Printer.verbose) {
          int status = packedMsg & 0xFF;
          int data1 = (packedMsg & 0xFF00)>>8;
          int data2 = (packedMsg & 0xFF0000)>>16;
          Printer.verbose(">> MidiInDevice callbackShortMessage: status: " + status + " data1: " + data1 + " data2: " + data2 + " timeStamp: " + timeStamp);
          }*/


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