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
26 package javax.sound.midi;
27
28 import java.util.List;
29
30 /**
31 * {@code MidiDevice} is the base interface for all MIDI devices. Common devices
32 * include synthesizers, sequencers, MIDI input ports, and MIDI output ports.
33 * <p>
34 * A {@code MidiDevice} can be a transmitter or a receiver of MIDI events, or
35 * both. Therefore, it can provide {@link Transmitter} or {@link Receiver}
36 * instances (or both). Typically, MIDI IN ports provide transmitters, MIDI OUT
37 * ports and synthesizers provide receivers. A Sequencer typically provides
38 * transmitters for playback and receivers for recording.
39 * <p>
40 * A {@code MidiDevice} can be opened and closed explicitly as well as
41 * implicitly. Explicit opening is accomplished by calling {@link #open},
42 * explicit closing is done by calling {@link #close} on the {@code MidiDevice}
43 * instance. If an application opens a {@code MidiDevice} explicitly, it has to
44 * close it explicitly to free system resources and enable the application to
45 * exit cleanly. Implicit opening is done by calling
46 * {@link MidiSystem#getReceiver} and {@link MidiSystem#getTransmitter}. The
47 * {@code MidiDevice} used by {@code MidiSystem.getReceiver} and
48 * {@code MidiSystem.getTransmitter} is implementation-dependant unless the
49 * properties {@code javax.sound.midi.Receiver} and
50 * {@code javax.sound.midi.Transmitter} are used (see the description of
51 * properties to select default providers in {@link MidiSystem}). A
52 * {@code MidiDevice} that was opened implicitly, is closed implicitly by
53 * closing the {@code Receiver} or {@code Transmitter} that resulted in opening
54 * it. If more than one implicitly opening {@code Receiver} or
55 * {@code Transmitter} were obtained by the application, the device is closed
56 * after the last {@code Receiver} or {@code Transmitter} has been closed. On
57 * the other hand, calling {@code getReceiver} or {@code getTransmitter} on the
58 * device instance directly does not open the device implicitly. Closing these
59 * {@code Transmitter}s and {@code Receiver}s does not close the device
60 * implicitly. To use a device with {@code Receiver}s or {@code Transmitter}s
61 * obtained this way, the device has to be opened and closed explicitly.
62 * <p>
63 * If implicit and explicit opening and closing are mixed on the same
64 * {@code MidiDevice} instance, the following rules apply:
65 *
66 * <ul>
67 * <li>After an explicit open (either before or after implicit opens), the
68 * device will not be closed by implicit closing. The only way to close an
69 * explicitly opened device is an explicit close.</li>
70 * <li>An explicit close always closes the device, even if it also has been
71 * opened implicitly. A subsequent implicit close has no further effect.</li>
72 * </ul>
73 *
74 * To detect if a MidiDevice represents a hardware MIDI port, the following
75 * programming technique can be used:
76 *
77 * <pre>{@code
78 * MidiDevice device = ...;
79 * if ( ! (device instanceof Sequencer) && ! (device instanceof Synthesizer)) {
80 * // we're now sure that device represents a MIDI port
81 * // ...
82 * }
83 * }</pre>
84 *
85 * <p>
86 * A {@code MidiDevice} includes a {@link Info} object to provide manufacturer
87 * information and so on.
88 *
89 * @author Kara Kytle
90 * @author Florian Bomers
91 * @see Synthesizer
92 * @see Sequencer
93 * @see Receiver
94 * @see Transmitter
95 */
96 public interface MidiDevice extends AutoCloseable {
97
98 /**
99 * Obtains information about the device, including its Java class and
100 * {@code Strings} containing its name, vendor, and description.
101 *
102 * @return device info
103 */
104 Info getDeviceInfo();
105
106 /**
107 * Opens the device, indicating that it should now acquire any system
108 * resources it requires and become operational.
109 * <p>
110 * An application opening a device explicitly with this call has to close
111 * the device by calling {@link #close}. This is necessary to release system
112 * resources and allow applications to exit cleanly.
113 * <p>
114 * Note that some devices, once closed, cannot be reopened. Attempts to
115 * reopen such a device will always result in a MidiUnavailableException.
116 *
117 * @throws MidiUnavailableException thrown if the device cannot be opened
118 * due to resource restrictions
119 * @throws SecurityException thrown if the device cannot be opened due to
120 * security restrictions
121 * @see #close
122 * @see #isOpen
123 */
124 void open() throws MidiUnavailableException;
125
126 /**
127 * Closes the device, indicating that the device should now release any
128 * system resources it is using.
129 * <p>
130 * All {@code Receiver} and {@code Transmitter} instances open from this
131 * device are closed. This includes instances retrieved via
132 * {@code MidiSystem}.
133 *
134 * @see #open
135 * @see #isOpen
136 */
137 void close();
138
139 /**
140 * Reports whether the device is open.
141 *
142 * @return {@code true} if the device is open, otherwise {@code false}
143 * @see #open
144 * @see #close
145 */
146 boolean isOpen();
147
148 /**
149 * Obtains the current time-stamp of the device, in microseconds. If a
150 * device supports time-stamps, it should start counting at 0 when the
151 * device is opened and continue incrementing its time-stamp in microseconds
152 * until the device is closed. If it does not support time-stamps, it should
153 * always return -1.
154 *
155 * @return the current time-stamp of the device in microseconds, or -1 if
156 * time-stamping is not supported by the device
157 */
158 long getMicrosecondPosition();
159
160 /**
161 * Obtains the maximum number of MIDI IN connections available on this MIDI
162 * device for receiving MIDI data.
163 *
164 * @return maximum number of MIDI IN connections, or -1 if an unlimited
165 * number of connections is available
166 */
167 int getMaxReceivers();
168
169 /**
170 * Obtains the maximum number of MIDI OUT connections available on this MIDI
171 * device for transmitting MIDI data.
172 *
173 * @return maximum number of MIDI OUT connections, or -1 if an unlimited
174 * number of connections is available
175 */
176 int getMaxTransmitters();
177
178 /**
179 * Obtains a MIDI IN receiver through which the MIDI device may receive MIDI
180 * data. The returned receiver must be closed when the application has
181 * finished using it.
182 * <p>
183 * Usually the returned receiver implements the {@code MidiDeviceReceiver}
184 * interface.
185 * <p>
186 * Obtaining a {@code Receiver} with this method does not open the device.
187 * To be able to use the device, it has to be opened explicitly by calling
188 * {@link #open}. Also, closing the {@code Receiver} does not close the
189 * device. It has to be closed explicitly by calling {@link #close}.
190 *
191 * @return a receiver for the device
192 * @throws MidiUnavailableException thrown if a receiver is not available
193 * due to resource restrictions
194 * @see Receiver#close()
195 */
196 Receiver getReceiver() throws MidiUnavailableException;
197
198 /**
199 * Returns all currently active, non-closed receivers connected with this
200 * MidiDevice. A receiver can be removed from the device by closing it.
201 * <p>
202 * Usually the returned receivers implement the {@code MidiDeviceReceiver}
203 * interface.
204 *
205 * @return an unmodifiable list of the open receivers
206 * @since 1.5
207 */
208 List<Receiver> getReceivers();
209
210 /**
211 * Obtains a MIDI OUT connection from which the MIDI device will transmit
212 * MIDI data. The returned transmitter must be closed when the application
213 * has finished using it.
214 * <p>
215 * Usually the returned transmitter implements the
216 * {@code MidiDeviceTransmitter} interface.
217 * <p>
218 * Obtaining a {@code Transmitter} with this method does not open the
219 * device. To be able to use the device, it has to be opened explicitly by
220 * calling {@link #open}. Also, closing the {@code Transmitter} does not
221 * close the device. It has to be closed explicitly by calling
222 * {@link #close}.
223 *
224 * @return a MIDI OUT transmitter for the device
225 * @throws MidiUnavailableException thrown if a transmitter is not available
226 * due to resource restrictions
227 * @see Transmitter#close()
228 */
229 Transmitter getTransmitter() throws MidiUnavailableException;
230
231 /**
232 * Returns all currently active, non-closed transmitters connected with this
233 * MidiDevice. A transmitter can be removed from the device by closing it.
234 * <p>
235 * Usually the returned transmitters implement the
236 * {@code MidiDeviceTransmitter} interface.
237 *
238 * @return an unmodifiable list of the open transmitters
239 * @since 1.5
240 */
241 List<Transmitter> getTransmitters();
242
243 /**
244 * A {@code MidiDevice.Info} object contains assorted data about a
245 * {@link MidiDevice}, including its name, the company who created it, and
246 * descriptive text.
247 *
248 * @see MidiDevice#getDeviceInfo
249 */
250 class Info {
251
252 /**
253 * The device's name.
254 */
255 private String name;
256
257 /**
258 * The name of the company who provides the device.
259 */
260 private String vendor;
261
262 /**
263 * A description of the device.
264 */
265 private String description;
266
267 /**
268 * Device version.
269 */
270 private String version;
271
272 /**
273 * Constructs a device info object.
274 *
275 * @param name the name of the device
276 * @param vendor the name of the company who provides the device
277 * @param description a description of the device
278 * @param version version information for the device
279 */
280 protected Info(String name, String vendor, String description,
281 String version) {
282
283 this.name = name;
284 this.vendor = vendor;
285 this.description = description;
286 this.version = version;
287 }
288
289 /**
290 * Reports whether two objects are equal. Returns {@code true} if the
291 * objects are identical.
292 *
293 * @param obj the reference object with which to compare this object
294 * @return {@code true} if this object is the same as the {@code obj}
295 * argument; {@code false} otherwise
296 */
297 public final boolean equals(Object obj) {
298 return super.equals(obj);
299 }
300
301 /**
302 * Finalizes the hashcode method.
303 */
304 public final int hashCode() {
305 return super.hashCode();
306 }
307
308 /**
309 * Obtains the name of the device.
310 *
311 * @return a string containing the device's name
312 */
313 public final String getName() {
314 return name;
315 }
316
317 /**
318 * Obtains the name of the company who supplies the device.
319 *
320 * @return device the vendor's name
321 */
322 public final String getVendor() {
323 return vendor;
324 }
325
326 /**
327 * Obtains the description of the device.
328 *
329 * @return a description of the device
330 */
331 public final String getDescription() {
332 return description;
333 }
334
335 /**
336 * Obtains the version of the device.
337 *
338 * @return textual version information for the device
339 */
340 public final String getVersion() {
341 return version;
342 }
343
344 /**
345 * Provides a string representation of the device information.
346 *
347 * @return a description of the info object
348 */
349 public final String toString() {
350 return name;
351 }
352 } // class Info
353 }