MidiInDeviceProvider.java revision 10444:f08705540498 
1/*
2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.media.sound;
27
28import javax.sound.midi.MidiDevice;
29
30
31/**
32 * MIDI input device provider.
33 *
34 * @author Kara Kytle
35 * @author Florian Bomers
36 */
37public final class MidiInDeviceProvider extends AbstractMidiDeviceProvider {
38
39    /** Cache of info objects for all MIDI output devices on the system. */
40    private static Info[] infos = null;
41
42    /** Cache of open MIDI input devices on the system. */
43    private static MidiDevice[] devices = null;
44
45    private static final boolean enabled;
46
47    // STATIC
48
49    static {
50        // initialize
51        Platform.initialize();
52        enabled = Platform.isMidiIOEnabled();
53    }
54
55    // CONSTRUCTOR
56
57    /**
58     * Required public no-arg constructor.
59     */
60    public MidiInDeviceProvider() {
61        if (Printer.trace) Printer.trace("MidiInDeviceProvider: constructor");
62    }
63
64    // implementation of abstract methods in AbstractMidiDeviceProvider
65
66    AbstractMidiDeviceProvider.Info createInfo(int index) {
67        if (!enabled) {
68            return null;
69        }
70        return new MidiInDeviceInfo(index, MidiInDeviceProvider.class);
71    }
72
73    MidiDevice createDevice(AbstractMidiDeviceProvider.Info info) {
74        if (enabled && (info instanceof MidiInDeviceInfo)) {
75            return new MidiInDevice(info);
76        }
77        return null;
78    }
79
80    int getNumDevices() {
81        if (!enabled) {
82            if (Printer.debug)Printer.debug("MidiInDevice not enabled, returning 0 devices");
83            return 0;
84        }
85        int numDevices = nGetNumDevices();
86        if (Printer.debug)Printer.debug("MidiInDeviceProvider.getNumDevices(): devices: " + numDevices);
87        return numDevices;
88    }
89
90    MidiDevice[] getDeviceCache() { return devices; }
91    void setDeviceCache(MidiDevice[] devices) { MidiInDeviceProvider.devices = devices; }
92    Info[] getInfoCache() { return infos; }
93    void setInfoCache(Info[] infos) { MidiInDeviceProvider.infos = infos; }
94
95
96    // INNER CLASSES
97
98    /**
99     * Info class for MidiInDevices.  Adds the
100     * provider's Class to keep the provider class from being
101     * unloaded.  Otherwise, at least on JDK1.1.7 and 1.1.8,
102     * the provider class can be unloaded.  Then, then the provider
103     * is next invoked, the static block is executed again and a new
104     * instance of the device object is created.  Even though the
105     * previous instance may still exist and be open / in use / etc.,
106     * the new instance will not reflect that state...
107     */
108    static final class MidiInDeviceInfo extends AbstractMidiDeviceProvider.Info {
109        private final Class<?> providerClass;
110
111        private MidiInDeviceInfo(int index, Class<?> providerClass) {
112            super(nGetName(index), nGetVendor(index), nGetDescription(index), nGetVersion(index), index);
113            this.providerClass = providerClass;
114        }
115
116    } // class MidiInDeviceInfo
117
118
119    // NATIVE METHODS
120
121    private static native int nGetNumDevices();
122    private static native String nGetName(int index);
123    private static native String nGetVendor(int index);
124    private static native String nGetDescription(int index);
125    private static native String nGetVersion(int index);
126}
127