JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2002, 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
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 */

package com.sun.media.sound;

import javax.sound.sampled.Mixer;
import javax.sound.sampled.spi.MixerProvider;

/**
 * DirectAudioDevice provider.
 *
 * @author Florian Bomers
 */
public final class DirectAudioDeviceProvider extends MixerProvider {

    /**
     * Set of info objects for all port input devices on the system.
     */
    private static DirectAudioDeviceInfo[] infos;

    /**
     * Set of all port input devices on the system.
     */
    private static DirectAudioDevice[] devices;

    static {
        // initialize
        Platform.initialize();
    }

    /**
     * Required public no-arg constructor.
     */
    public DirectAudioDeviceProvider() {
        synchronized (DirectAudioDeviceProvider.class) {
            if (Platform.isDirectAudioEnabled()) {
                init();
            } else {
                infos = new DirectAudioDeviceInfo[0];
                devices = new DirectAudioDevice[0];
            }
        }
    }

    private static void init() {
        // get the number of input devices
        int numDevices = nGetNumDevices();

        if (infos == null || infos.length != numDevices) {
            // initialize the arrays
            infos = new DirectAudioDeviceInfo[numDevices];
            devices = new DirectAudioDevice[numDevices];

            // fill in the info objects now.
            for (int i = 0; i < infos.length; i++) {
                infos[i] = nNewDirectAudioDeviceInfo(i);
            }
        }
    }

    @Override
    public Mixer.Info[] getMixerInfo() {
        synchronized (DirectAudioDeviceProvider.class) {
            Mixer.Info[] localArray = new Mixer.Info[infos.length];
            System.arraycopy(infos, 0, localArray, 0, infos.length);
            return localArray;
        }
    }

    @Override
    public Mixer getMixer(Mixer.Info info) {
        synchronized (DirectAudioDeviceProvider.class) {
            // if the default device is asked, we provide the mixer
            // with SourceDataLine's
            if (info == null) {
                for (int i = 0; i < infos.length; i++) {
                    Mixer mixer = getDevice(infos[i]);
                    if (mixer.getSourceLineInfo().length > 0) {
                        return mixer;
                    }
                }
            }
            // otherwise get the first mixer that matches
            // the requested info object
            for (int i = 0; i < infos.length; i++) {
                if (infos[i].equals(info)) {
                    return getDevice(infos[i]);
                }
            }
        }
        throw new IllegalArgumentException(
                String.format("Mixer %s not supported by this provider", info));
    }

    private static Mixer getDevice(DirectAudioDeviceInfo info) {
        int index = info.getIndex();
        if (devices[index] == null) {
            devices[index] = new DirectAudioDevice(info);
        }
        return devices[index];
    }

    /**
     * Info class for DirectAudioDevices.  Adds an index value and a string for
     * making native references to a particular device.
     * This constructor is called from native.
     */
    static final class DirectAudioDeviceInfo extends Mixer.Info {
        private final int index;
        private final int maxSimulLines;

        // For ALSA, the deviceID contains the encoded card index, device index, and sub-device-index
        private final int deviceID;

        private DirectAudioDeviceInfo(int index, int deviceID, int maxSimulLines,
                                      String name, String vendor,
                                      String description, String version) {
            super(name, vendor, "Direct Audio Device: "+description, version);

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