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 @Override 138 void close(); 139 140 /** 141 * Reports whether the device is open. 142 * 143 * @return {@code true} if the device is open, otherwise {@code false} 144 * @see #open 145 * @see #close 146 */ 147 boolean isOpen(); 148 149 /** 150 * Obtains the current time-stamp of the device, in microseconds. If a 151 * device supports time-stamps, it should start counting at 0 when the 152 * device is opened and continue incrementing its time-stamp in microseconds 153 * until the device is closed. If it does not support time-stamps, it should 154 * always return -1. 155 * 156 * @return the current time-stamp of the device in microseconds, or -1 if 157 * time-stamping is not supported by the device 158 */ 159 long getMicrosecondPosition(); 160 161 /** 162 * Obtains the maximum number of MIDI IN connections available on this MIDI 163 * device for receiving MIDI data. 164 * 165 * @return maximum number of MIDI IN connections, or -1 if an unlimited 166 * number of connections is available 167 */ 168 int getMaxReceivers(); 169 170 /** 171 * Obtains the maximum number of MIDI OUT connections available on this MIDI 172 * device for transmitting MIDI data. 173 * 174 * @return maximum number of MIDI OUT connections, or -1 if an unlimited 175 * number of connections is available 176 */ 177 int getMaxTransmitters(); 178 179 /** 180 * Obtains a MIDI IN receiver through which the MIDI device may receive MIDI 181 * data. The returned receiver must be closed when the application has 182 * finished using it. 183 * <p> 184 * Usually the returned receiver implements the {@code MidiDeviceReceiver} 185 * interface. 186 * <p> 187 * Obtaining a {@code Receiver} with this method does not open the device. 188 * To be able to use the device, it has to be opened explicitly by calling 189 * {@link #open}. Also, closing the {@code Receiver} does not close the 190 * device. It has to be closed explicitly by calling {@link #close}. 191 * 192 * @return a receiver for the device 193 * @throws MidiUnavailableException thrown if a receiver is not available 194 * due to resource restrictions 195 * @see Receiver#close() 196 */ 197 Receiver getReceiver() throws MidiUnavailableException; 198 199 /** 200 * Returns all currently active, non-closed receivers connected with this 201 * MidiDevice. A receiver can be removed from the device by closing it. 202 * <p> 203 * Usually the returned receivers implement the {@code MidiDeviceReceiver} 204 * interface. 205 * 206 * @return an unmodifiable list of the open receivers 207 * @since 1.5 208 */ 209 List<Receiver> getReceivers(); 210 211 /** 212 * Obtains a MIDI OUT connection from which the MIDI device will transmit 213 * MIDI data. The returned transmitter must be closed when the application 214 * has finished using it. 215 * <p> 216 * Usually the returned transmitter implements the 217 * {@code MidiDeviceTransmitter} interface. 218 * <p> 219 * Obtaining a {@code Transmitter} with this method does not open the 220 * device. To be able to use the device, it has to be opened explicitly by 221 * calling {@link #open}. Also, closing the {@code Transmitter} does not 222 * close the device. It has to be closed explicitly by calling 223 * {@link #close}. 224 * 225 * @return a MIDI OUT transmitter for the device 226 * @throws MidiUnavailableException thrown if a transmitter is not available 227 * due to resource restrictions 228 * @see Transmitter#close() 229 */ 230 Transmitter getTransmitter() throws MidiUnavailableException; 231 232 /** 233 * Returns all currently active, non-closed transmitters connected with this 234 * MidiDevice. A transmitter can be removed from the device by closing it. 235 * <p> 236 * Usually the returned transmitters implement the 237 * {@code MidiDeviceTransmitter} interface. 238 * 239 * @return an unmodifiable list of the open transmitters 240 * @since 1.5 241 */ 242 List<Transmitter> getTransmitters(); 243 244 /** 245 * A {@code MidiDevice.Info} object contains assorted data about a 246 * {@link MidiDevice}, including its name, the company who created it, and 247 * descriptive text. 248 * 249 * @see MidiDevice#getDeviceInfo 250 */ 251 class Info { 252 253 /** 254 * The device's name. 255 */ 256 private final String name; 257 258 /** 259 * The name of the company who provides the device. 260 */ 261 private final String vendor; 262 263 /** 264 * A description of the device. 265 */ 266 private final String description; 267 268 /** 269 * Device version. 270 */ 271 private final String version; 272 273 /** 274 * Constructs a device info object. 275 * 276 * @param name the name of the device 277 * @param vendor the name of the company who provides the device 278 * @param description a description of the device 279 * @param version version information for the device 280 */ 281 protected Info(String name, String vendor, String description, 282 String version) { 283 284 this.name = name; 285 this.vendor = vendor; 286 this.description = description; 287 this.version = version; 288 } 289 290 /** 291 * Reports whether two objects are equal. Returns {@code true} if the 292 * objects are identical. 293 * 294 * @param obj the reference object with which to compare this object 295 * @return {@code true} if this object is the same as the {@code obj} 296 * argument; {@code false} otherwise 297 */ 298 @Override 299 public final boolean equals(Object obj) { 300 return super.equals(obj); 301 } 302 303 /** 304 * Finalizes the hashcode method. 305 */ 306 @Override 307 public final int hashCode() { 308 return super.hashCode(); 309 } 310 311 /** 312 * Obtains the name of the device. 313 * 314 * @return a string containing the device's name 315 */ 316 public final String getName() { 317 return name; 318 } 319 320 /** 321 * Obtains the name of the company who supplies the device. 322 * 323 * @return device the vendor's name 324 */ 325 public final String getVendor() { 326 return vendor; 327 } 328 329 /** 330 * Obtains the description of the device. 331 * 332 * @return a description of the device 333 */ 334 public final String getDescription() { 335 return description; 336 } 337 338 /** 339 * Obtains the version of the device. 340 * 341 * @return textual version information for the device 342 */ 343 public final String getVersion() { 344 return version; 345 } 346 347 /** 348 * Provides a string representation of the device information. 349 * 350 * @return a description of the info object 351 */ 352 @Override 353 public final String toString() { 354 return name; 355 } 356 } // class Info 357 }