8201279: javax.sound tests should not set java.home system property
Reviewed-by: prr, rriggs
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package javax.sound.sampled;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Properties;
import java.util.Set;
import java.util.Vector;
import javax.sound.sampled.spi.AudioFileReader;
import javax.sound.sampled.spi.AudioFileWriter;
import javax.sound.sampled.spi.FormatConversionProvider;
import javax.sound.sampled.spi.MixerProvider;
import com.sun.media.sound.JDK13Services;
/* $fb TODO:
* - consistent usage of (typed) collections
*/
/**
* The {@code AudioSystem} class acts as the entry point to the sampled-audio
* system resources. This class lets you query and access the mixers that are
* installed on the system. {@code AudioSystem} includes a number of methods for
* converting audio data between different formats, and for translating between
* audio files and streams. It also provides a method for obtaining a
* {@link Line} directly from the {@code AudioSystem} without dealing explicitly
* with mixers.
* <p>
* Properties can be used to specify the default mixer for specific line types.
* Both system properties and a properties file are considered. The
* "sound.properties" properties file is read from an implementation-specific
* location (typically it is the {@code conf} directory in the Java installation
* directory). The optional "javax.sound.config.file" system property can be
* used to specify the properties file that will be read as the initial
* configuration. If a property exists both as a system property and in the
* properties file, the system property takes precedence. If none is specified,
* a suitable default is chosen among the available devices. The syntax of the
* properties file is specified in
* {@link Properties#load(InputStream) Properties.load}. The following table
* lists the available property keys and which methods consider them:
*
* <table class="striped">
* <caption>Audio System Property Keys</caption>
* <thead>
* <tr>
* <th scope="col">Property Key
* <th scope="col">Interface
* <th scope="col">Affected Method(s)
* </thead>
* <tbody>
* <tr>
* <th scope="row">{@code javax.sound.sampled.Clip}
* <td>{@link Clip}
* <td>{@link #getLine}, {@link #getClip}
* <tr>
* <th scope="row">{@code javax.sound.sampled.Port}
* <td>{@link Port}
* <td>{@link #getLine}
* <tr>
* <th scope="row">{@code javax.sound.sampled.SourceDataLine}
* <td>{@link SourceDataLine}
* <td>{@link #getLine}, {@link #getSourceDataLine}
* <tr>
* <th scope="row">{@code javax.sound.sampled.TargetDataLine}
* <td>{@link TargetDataLine}
* <td>{@link #getLine}, {@link #getTargetDataLine}
* </tbody>
* </table>
*
* The property value consists of the provider class name and the mixer name,
* separated by the hash mark ("#"). The provider class name is the
* fully-qualified name of a concrete {@link MixerProvider mixer provider}
* class. The mixer name is matched against the {@code String} returned by the
* {@code getName} method of {@code Mixer.Info}. Either the class name, or the
* mixer name may be omitted. If only the class name is specified, the trailing
* hash mark is optional.
* <p>
* If the provider class is specified, and it can be successfully retrieved from
* the installed providers, the list of {@code Mixer.Info} objects is retrieved
* from the provider. Otherwise, or when these mixers do not provide a
* subsequent match, the list is retrieved from {@link #getMixerInfo} to contain
* all available {@code Mixer.Info} objects.
* <p>
* If a mixer name is specified, the resulting list of {@code Mixer.Info}
* objects is searched: the first one with a matching name, and whose
* {@code Mixer} provides the respective line interface, will be returned. If no
* matching {@code Mixer.Info} object is found, or the mixer name is not
* specified, the first mixer from the resulting list, which provides the
* respective line interface, will be returned.
* <p>
* For example, the property {@code javax.sound.sampled.Clip} with a value
* {@code "com.sun.media.sound.MixerProvider#SunClip"} will have the following
* consequences when {@code getLine} is called requesting a {@code Clip}
* instance: if the class {@code com.sun.media.sound.MixerProvider} exists in
* the list of installed mixer providers, the first {@code Clip} from the first
* mixer with name {@code "SunClip"} will be returned. If it cannot be found,
* the first {@code Clip} from the first mixer of the specified provider will be
* returned, regardless of name. If there is none, the first {@code Clip} from
* the first {@code Mixer} with name {@code "SunClip"} in the list of all mixers
* (as returned by {@code getMixerInfo}) will be returned, or, if not found, the
* first {@code Clip} of the first {@code Mixer} that can be found in the list
* of all mixers is returned. If that fails, too, an
* {@code IllegalArgumentException} is thrown.
*
* @author Kara Kytle
* @author Florian Bomers
* @author Matthias Pfisterer
* @author Kevin P. Smith
* @see AudioFormat
* @see AudioInputStream
* @see Mixer
* @see Line
* @see Line.Info
* @since 1.3
*/
public class AudioSystem {
/**
* An integer that stands for an unknown numeric value. This value is
* appropriate only for signed quantities that do not normally take negative
* values. Examples include file sizes, frame sizes, buffer sizes, and
* sample rates. A number of Java Sound constructors accept a value of
* {@code NOT_SPECIFIED} for such parameters. Other methods may also accept
* or return this value, as documented.
*/
public static final int NOT_SPECIFIED = -1;
/**
* Private no-args constructor for ensuring against instantiation.
*/
private AudioSystem() {
}
/**
* Obtains an array of mixer info objects that represents the set of audio
* mixers that are currently installed on the system.
*
* @return an array of info objects for the currently installed mixers. If
* no mixers are available on the system, an array of length 0 is
* returned.
* @see #getMixer
*/
public static Mixer.Info[] getMixerInfo() {
List<Mixer.Info> infos = getMixerInfoList();
Mixer.Info[] allInfos = infos.toArray(new Mixer.Info[infos.size()]);
return allInfos;
}
/**
* Obtains the requested audio mixer.
*
* @param info a {@code Mixer.Info} object representing the desired mixer,
* or {@code null} for the system default mixer
* @return the requested mixer
* @throws SecurityException if the requested mixer is unavailable because
* of security restrictions
* @throws IllegalArgumentException if the info object does not represent a
* mixer installed on the system
* @see #getMixerInfo
*/
public static Mixer getMixer(final Mixer.Info info) {
for (final MixerProvider provider : getMixerProviders()) {
try {
return provider.getMixer(info);
} catch (IllegalArgumentException | NullPointerException ignored) {
// The MixerProvider.getMixer(null) should return default Mixer,
// This behaviour was assumed from the beginning, but strictly
// specified only in the jdk9. Since the jdk1.1.5 we skipped
// NPE for some reason and therefore skipped some
// implementations of MixerProviders, which throw NPE. To keep
// support of such implementations, we still ignore NPE.
}
}
throw new IllegalArgumentException(
String.format("Mixer not supported: %s", info));
}
//$$fb 2002-11-26: fix for 4757930: DOC: AudioSystem.getTarget/SourceLineInfo() is ambiguous
/**
* Obtains information about all source lines of a particular type that are
* supported by the installed mixers.
*
* @param info a {@code Line.Info} object that specifies the kind of lines
* about which information is requested
* @return an array of {@code Line.Info} objects describing source lines
* matching the type requested. If no matching source lines are
* supported, an array of length 0 is returned.
* @see Mixer#getSourceLineInfo(Line.Info)
*/
public static Line.Info[] getSourceLineInfo(Line.Info info) {
Vector<Line.Info> vector = new Vector<>();
Line.Info[] currentInfoArray;
Mixer mixer;
Line.Info fullInfo = null;
Mixer.Info[] infoArray = getMixerInfo();
for (int i = 0; i < infoArray.length; i++) {
mixer = getMixer(infoArray[i]);
currentInfoArray = mixer.getSourceLineInfo(info);
for (int j = 0; j < currentInfoArray.length; j++) {
vector.addElement(currentInfoArray[j]);
}
}
Line.Info[] returnedArray = new Line.Info[vector.size()];
for (int i = 0; i < returnedArray.length; i++) {
returnedArray[i] = vector.get(i);
}
return returnedArray;
}
/**
* Obtains information about all target lines of a particular type that are
* supported by the installed mixers.
*
* @param info a {@code Line.Info} object that specifies the kind of lines
* about which information is requested
* @return an array of {@code Line.Info} objects describing target lines
* matching the type requested. If no matching target lines are
* supported, an array of length 0 is returned.
* @see Mixer#getTargetLineInfo(Line.Info)
*/
public static Line.Info[] getTargetLineInfo(Line.Info info) {
Vector<Line.Info> vector = new Vector<>();
Line.Info[] currentInfoArray;
Mixer mixer;
Line.Info fullInfo = null;
Mixer.Info[] infoArray = getMixerInfo();
for (int i = 0; i < infoArray.length; i++) {
mixer = getMixer(infoArray[i]);
currentInfoArray = mixer.getTargetLineInfo(info);
for (int j = 0; j < currentInfoArray.length; j++) {
vector.addElement(currentInfoArray[j]);
}
}
Line.Info[] returnedArray = new Line.Info[vector.size()];
for (int i = 0; i < returnedArray.length; i++) {
returnedArray[i] = vector.get(i);
}
return returnedArray;
}
/**
* Indicates whether the system supports any lines that match the specified
* {@code Line.Info} object. A line is supported if any installed mixer
* supports it.
*
* @param info a {@code Line.Info} object describing the line for which
* support is queried
* @return {@code true} if at least one matching line is supported,
* otherwise {@code false}
* @see Mixer#isLineSupported(Line.Info)
*/
public static boolean isLineSupported(Line.Info info) {
Mixer mixer;
Mixer.Info[] infoArray = getMixerInfo();
for (int i = 0; i < infoArray.length; i++) {
if( infoArray[i] != null ) {
mixer = getMixer(infoArray[i]);
if (mixer.isLineSupported(info)) {
return true;
}
}
}
return false;
}
/**
* Obtains a line that matches the description in the specified
* {@code Line.Info} object.
* <p>
* If a {@code DataLine} is requested, and {@code info} is an instance of
* {@code DataLine.Info} specifying at least one fully qualified audio
* format, the last one will be used as the default format of the returned
* {@code DataLine}.
* <p>
* If system properties
* {@code javax.sound.sampled.Clip},
* {@code javax.sound.sampled.Port},
* {@code javax.sound.sampled.SourceDataLine} and
* {@code javax.sound.sampled.TargetDataLine} are defined or they are
* defined in the file "sound.properties", they are used to retrieve default
* lines. For details, refer to the {@link AudioSystem class description}.
*
* If the respective property is not set, or the mixer requested in the
* property is not installed or does not provide the requested line, all
* installed mixers are queried for the requested line type. A Line will be
* returned from the first mixer providing the requested line type.
*
* @param info a {@code Line.Info} object describing the desired kind of
* line
* @return a line of the requested kind
* @throws LineUnavailableException if a matching line is not available due
* to resource restrictions
* @throws SecurityException if a matching line is not available due to
* security restrictions
* @throws IllegalArgumentException if the system does not support at least
* one line matching the specified {@code Line.Info} object through
* any installed mixer
*/
public static Line getLine(Line.Info info) throws LineUnavailableException {
LineUnavailableException lue = null;
List<MixerProvider> providers = getMixerProviders();
// 1: try from default mixer for this line class
try {
Mixer mixer = getDefaultMixer(providers, info);
if (mixer != null && mixer.isLineSupported(info)) {
return mixer.getLine(info);
}
} catch (LineUnavailableException e) {
lue = e;
} catch (IllegalArgumentException iae) {
// must not happen... but better to catch it here,
// if plug-ins are badly written
}
// 2: if that doesn't work, try to find any mixing mixer
for(int i = 0; i < providers.size(); i++) {
MixerProvider provider = providers.get(i);
Mixer.Info[] infos = provider.getMixerInfo();
for (int j = 0; j < infos.length; j++) {
try {
Mixer mixer = provider.getMixer(infos[j]);
// see if this is an appropriate mixer which can mix
if (isAppropriateMixer(mixer, info, true)) {
return mixer.getLine(info);
}
} catch (LineUnavailableException e) {
lue = e;
} catch (IllegalArgumentException iae) {
// must not happen... but better to catch it here,
// if plug-ins are badly written
}
}
}
// 3: if that didn't work, try to find any non-mixing mixer
for(int i = 0; i < providers.size(); i++) {
MixerProvider provider = providers.get(i);
Mixer.Info[] infos = provider.getMixerInfo();
for (int j = 0; j < infos.length; j++) {
try {
Mixer mixer = provider.getMixer(infos[j]);
// see if this is an appropriate mixer which can mix
if (isAppropriateMixer(mixer, info, false)) {
return mixer.getLine(info);
}
} catch (LineUnavailableException e) {
lue = e;
} catch (IllegalArgumentException iae) {
// must not happen... but better to catch it here,
// if plug-ins are badly written
}
}
}
// if this line was supported but was not available, throw the last
// LineUnavailableException we got (??).
if (lue != null) {
throw lue;
}
// otherwise, the requested line was not supported, so throw
// an Illegal argument exception
throw new IllegalArgumentException("No line matching " +
info.toString() + " is supported.");
}
/**
* Obtains a clip that can be used for playing back an audio file or an
* audio stream. The returned clip will be provided by the default system
* mixer, or, if not possible, by any other mixer installed in the system
* that supports a {@code Clip} object.
* <p>
* The returned clip must be opened with the {@code open(AudioFormat)} or
* {@code open(AudioInputStream)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
* <p>
* If the system property {@code javax.sound.sampled.Clip} is defined or it
* is defined in the file "sound.properties", it is used to retrieve the
* default clip. For details, refer to the
* {@link AudioSystem class description}.
*
* @return the desired clip object
* @throws LineUnavailableException if a clip object is not available due to
* resource restrictions
* @throws SecurityException if a clip object is not available due to
* security restrictions
* @throws IllegalArgumentException if the system does not support at least
* one clip instance through any installed mixer
* @see #getClip(Mixer.Info)
* @since 1.5
*/
public static Clip getClip() throws LineUnavailableException{
AudioFormat format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,
AudioSystem.NOT_SPECIFIED,
16, 2, 4,
AudioSystem.NOT_SPECIFIED, true);
DataLine.Info info = new DataLine.Info(Clip.class, format);
return (Clip) AudioSystem.getLine(info);
}
/**
* Obtains a clip from the specified mixer that can be used for playing back
* an audio file or an audio stream.
* <p>
* The returned clip must be opened with the {@code open(AudioFormat)} or
* {@code open(AudioInputStream)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
*
* @param mixerInfo a {@code Mixer.Info} object representing the desired
* mixer, or {@code null} for the system default mixer
* @return a clip object from the specified mixer
* @throws LineUnavailableException if a clip is not available from this
* mixer due to resource restrictions
* @throws SecurityException if a clip is not available from this mixer due
* to security restrictions
* @throws IllegalArgumentException if the system does not support at least
* one clip through the specified mixer
* @see #getClip()
* @since 1.5
*/
public static Clip getClip(Mixer.Info mixerInfo) throws LineUnavailableException{
AudioFormat format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,
AudioSystem.NOT_SPECIFIED,
16, 2, 4,
AudioSystem.NOT_SPECIFIED, true);
DataLine.Info info = new DataLine.Info(Clip.class, format);
Mixer mixer = AudioSystem.getMixer(mixerInfo);
return (Clip) mixer.getLine(info);
}
/**
* Obtains a source data line that can be used for playing back audio data
* in the format specified by the {@code AudioFormat} object. The returned
* line will be provided by the default system mixer, or, if not possible,
* by any other mixer installed in the system that supports a matching
* {@code SourceDataLine} object.
* <p>
* The returned line should be opened with the {@code open(AudioFormat)} or
* {@code open(AudioFormat, int)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
* <p>
* The returned {@code SourceDataLine}'s default audio format will be
* initialized with {@code format}.
* <p>
* If the system property {@code javax.sound.sampled.SourceDataLine} is
* defined or it is defined in the file "sound.properties", it is used to
* retrieve the default source data line. For details, refer to the
* {@link AudioSystem class description}.
*
* @param format an {@code AudioFormat} object specifying the supported
* audio format of the returned line, or {@code null} for any audio
* format
* @return the desired {@code SourceDataLine} object
* @throws LineUnavailableException if a matching source data line is not
* available due to resource restrictions
* @throws SecurityException if a matching source data line is not available
* due to security restrictions
* @throws IllegalArgumentException if the system does not support at least
* one source data line supporting the specified audio format
* through any installed mixer
* @see #getSourceDataLine(AudioFormat, Mixer.Info)
* @since 1.5
*/
public static SourceDataLine getSourceDataLine(AudioFormat format)
throws LineUnavailableException{
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
return (SourceDataLine) AudioSystem.getLine(info);
}
/**
* Obtains a source data line that can be used for playing back audio data
* in the format specified by the {@code AudioFormat} object, provided by
* the mixer specified by the {@code Mixer.Info} object.
* <p>
* The returned line should be opened with the {@code open(AudioFormat)} or
* {@code open(AudioFormat, int)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
* <p>
* The returned {@code SourceDataLine}'s default audio format will be
* initialized with {@code format}.
*
* @param format an {@code AudioFormat} object specifying the supported
* audio format of the returned line, or {@code null} for any audio
* format
* @param mixerinfo a {@code Mixer.Info} object representing the desired
* mixer, or {@code null} for the system default mixer
* @return the desired {@code SourceDataLine} object
* @throws LineUnavailableException if a matching source data line is not
* available from the specified mixer due to resource restrictions
* @throws SecurityException if a matching source data line is not available
* from the specified mixer due to security restrictions
* @throws IllegalArgumentException if the specified mixer does not support
* at least one source data line supporting the specified audio
* format
* @see #getSourceDataLine(AudioFormat)
* @since 1.5
*/
public static SourceDataLine getSourceDataLine(AudioFormat format,
Mixer.Info mixerinfo)
throws LineUnavailableException{
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
Mixer mixer = AudioSystem.getMixer(mixerinfo);
return (SourceDataLine) mixer.getLine(info);
}
/**
* Obtains a target data line that can be used for recording audio data in
* the format specified by the {@code AudioFormat} object. The returned line
* will be provided by the default system mixer, or, if not possible, by any
* other mixer installed in the system that supports a matching
* {@code TargetDataLine} object.
* <p>
* The returned line should be opened with the {@code open(AudioFormat)} or
* {@code open(AudioFormat, int)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
* <p>
* The returned {@code TargetDataLine}'s default audio format will be
* initialized with {@code format}.
* <p>
* If the system property {@code javax.sound.sampled.TargetDataLine} is
* defined or it is defined in the file "sound.properties", it is used to
* retrieve the default target data line. For details, refer to the
* {@link AudioSystem class description}.
*
* @param format an {@code AudioFormat} object specifying the supported
* audio format of the returned line, or {@code null} for any audio
* format
* @return the desired {@code TargetDataLine} object
* @throws LineUnavailableException if a matching target data line is not
* available due to resource restrictions
* @throws SecurityException if a matching target data line is not available
* due to security restrictions
* @throws IllegalArgumentException if the system does not support at least
* one target data line supporting the specified audio format
* through any installed mixer
* @see #getTargetDataLine(AudioFormat, Mixer.Info)
* @see AudioPermission
* @since 1.5
*/
public static TargetDataLine getTargetDataLine(AudioFormat format)
throws LineUnavailableException{
DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
return (TargetDataLine) AudioSystem.getLine(info);
}
/**
* Obtains a target data line that can be used for recording audio data in
* the format specified by the {@code AudioFormat} object, provided by the
* mixer specified by the {@code Mixer.Info} object.
* <p>
* The returned line should be opened with the {@code open(AudioFormat)} or
* {@code open(AudioFormat, int)} method.
* <p>
* This is a high-level method that uses {@code getMixer} and
* {@code getLine} internally.
* <p>
* The returned {@code TargetDataLine}'s default audio format will be
* initialized with {@code format}.
*
* @param format an {@code AudioFormat} object specifying the supported
* audio format of the returned line, or {@code null} for any audio
* format
* @param mixerinfo a {@code Mixer.Info} object representing the desired
* mixer, or {@code null} for the system default mixer
* @return the desired {@code TargetDataLine} object
* @throws LineUnavailableException if a matching target data line is not
* available from the specified mixer due to resource restrictions
* @throws SecurityException if a matching target data line is not available
* from the specified mixer due to security restrictions
* @throws IllegalArgumentException if the specified mixer does not support
* at least one target data line supporting the specified audio
* format
* @see #getTargetDataLine(AudioFormat)
* @see AudioPermission
* @since 1.5
*/
public static TargetDataLine getTargetDataLine(AudioFormat format,
Mixer.Info mixerinfo)
throws LineUnavailableException {
DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
Mixer mixer = AudioSystem.getMixer(mixerinfo);
return (TargetDataLine) mixer.getLine(info);
}
// $$fb 2002-04-12: fix for 4662082: behavior of AudioSystem.getTargetEncodings() methods doesn't match the spec
/**
* Obtains the encodings that the system can obtain from an audio input
* stream with the specified encoding using the set of installed format
* converters.
*
* @param sourceEncoding the encoding for which conversion support is
* queried
* @return array of encodings. If {@code sourceEncoding} is not supported,
* an array of length 0 is returned. Otherwise, the array will have
* a length of at least 1, representing {@code sourceEncoding}
* (no conversion).
* @throws NullPointerException if {@code sourceEncoding} is {@code null}
*/
public static AudioFormat.Encoding[] getTargetEncodings(AudioFormat.Encoding sourceEncoding) {
Objects.requireNonNull(sourceEncoding);
List<FormatConversionProvider> codecs = getFormatConversionProviders();
Vector<AudioFormat.Encoding> encodings = new Vector<>();
AudioFormat.Encoding encs[] = null;
// gather from all the codecs
for(int i=0; i<codecs.size(); i++ ) {
FormatConversionProvider codec = codecs.get(i);
if( codec.isSourceEncodingSupported( sourceEncoding ) ) {
encs = codec.getTargetEncodings();
for (int j = 0; j < encs.length; j++) {
encodings.addElement( encs[j] );
}
}
}
if (!encodings.contains(sourceEncoding)) {
encodings.addElement(sourceEncoding);
}
return encodings.toArray(new AudioFormat.Encoding[encodings.size()]);
}
// $$fb 2002-04-12: fix for 4662082: behavior of AudioSystem.getTargetEncodings() methods doesn't match the spec
/**
* Obtains the encodings that the system can obtain from an audio input
* stream with the specified format using the set of installed format
* converters.
*
* @param sourceFormat the audio format for which conversion is queried
* @return array of encodings. If {@code sourceFormat}is not supported, an
* array of length 0 is returned. Otherwise, the array will have a
* length of at least 1, representing the encoding of
* {@code sourceFormat} (no conversion).
* @throws NullPointerException if {@code sourceFormat} is {@code null}
*/
public static AudioFormat.Encoding[] getTargetEncodings(AudioFormat sourceFormat) {
Objects.requireNonNull(sourceFormat);
List<FormatConversionProvider> codecs = getFormatConversionProviders();
List<AudioFormat.Encoding> encs = new ArrayList<>();
// gather from all the codecs
for (final FormatConversionProvider codec : codecs) {
Collections.addAll(encs, codec.getTargetEncodings(sourceFormat));
}
if (!encs.contains(sourceFormat.getEncoding())) {
encs.add(sourceFormat.getEncoding());
}
return encs.toArray(new AudioFormat.Encoding[encs.size()]);
}
/**
* Indicates whether an audio input stream of the specified encoding can be
* obtained from an audio input stream that has the specified format.
*
* @param targetEncoding the desired encoding after conversion
* @param sourceFormat the audio format before conversion
* @return {@code true} if the conversion is supported, otherwise
* {@code false}
* @throws NullPointerException if {@code targetEncoding} or
* {@code sourceFormat} are {@code null}
*/
public static boolean isConversionSupported(AudioFormat.Encoding targetEncoding, AudioFormat sourceFormat) {
Objects.requireNonNull(targetEncoding);
Objects.requireNonNull(sourceFormat);
if (sourceFormat.getEncoding().equals(targetEncoding)) {
return true;
}
List<FormatConversionProvider> codecs = getFormatConversionProviders();
for(int i=0; i<codecs.size(); i++ ) {
FormatConversionProvider codec = codecs.get(i);
if(codec.isConversionSupported(targetEncoding,sourceFormat) ) {
return true;
}
}
return false;
}
/**
* Obtains an audio input stream of the indicated encoding, by converting
* the provided audio input stream.
*
* @param targetEncoding the desired encoding after conversion
* @param sourceStream the stream to be converted
* @return an audio input stream of the indicated encoding
* @throws IllegalArgumentException if the conversion is not supported
* @throws NullPointerException if {@code targetEncoding} or
* {@code sourceStream} are {@code null}
* @see #getTargetEncodings(AudioFormat.Encoding)
* @see #getTargetEncodings(AudioFormat)
* @see #isConversionSupported(AudioFormat.Encoding, AudioFormat)
* @see #getAudioInputStream(AudioFormat, AudioInputStream)
*/
public static AudioInputStream getAudioInputStream(AudioFormat.Encoding targetEncoding,
AudioInputStream sourceStream) {
Objects.requireNonNull(targetEncoding);
Objects.requireNonNull(sourceStream);
if (sourceStream.getFormat().getEncoding().equals(targetEncoding)) {
return sourceStream;
}
List<FormatConversionProvider> codecs = getFormatConversionProviders();
for(int i = 0; i < codecs.size(); i++) {
FormatConversionProvider codec = codecs.get(i);
if( codec.isConversionSupported( targetEncoding, sourceStream.getFormat() ) ) {
return codec.getAudioInputStream( targetEncoding, sourceStream );
}
}
// we ran out of options, throw an exception
throw new IllegalArgumentException("Unsupported conversion: " + targetEncoding + " from " + sourceStream.getFormat());
}
/**
* Obtains the formats that have a particular encoding and that the system
* can obtain from a stream of the specified format using the set of
* installed format converters.
*
* @param targetEncoding the desired encoding after conversion
* @param sourceFormat the audio format before conversion
* @return array of formats. If no formats of the specified encoding are
* supported, an array of length 0 is returned.
* @throws NullPointerException if {@code targetEncoding} or
* {@code sourceFormat} are {@code null}
*/
public static AudioFormat[] getTargetFormats(AudioFormat.Encoding targetEncoding, AudioFormat sourceFormat) {
Objects.requireNonNull(targetEncoding);
Objects.requireNonNull(sourceFormat);
List<FormatConversionProvider> codecs = getFormatConversionProviders();
List<AudioFormat> formats = new ArrayList<>();
boolean matchFound = false;
// gather from all the codecs
for (final FormatConversionProvider codec : codecs) {
AudioFormat[] elements = codec
.getTargetFormats(targetEncoding, sourceFormat);
for (AudioFormat format : elements) {
formats.add(format);
if (sourceFormat.matches(format)) {
matchFound = true;
}
}
}
if (targetEncoding.equals(sourceFormat.getEncoding())) {
if (!matchFound) {
formats.add(sourceFormat);
}
}
return formats.toArray(new AudioFormat[formats.size()]);
}
/**
* Indicates whether an audio input stream of a specified format can be
* obtained from an audio input stream of another specified format.
*
* @param targetFormat the desired audio format after conversion
* @param sourceFormat the audio format before conversion
* @return {@code true} if the conversion is supported, otherwise
* {@code false}
* @throws NullPointerException if {@code targetFormat} or
* {@code sourceFormat} are {@code null}
*/
public static boolean isConversionSupported(AudioFormat targetFormat, AudioFormat sourceFormat) {
Objects.requireNonNull(targetFormat);
Objects.requireNonNull(sourceFormat);
if (sourceFormat.matches(targetFormat)) {
return true;
}
List<FormatConversionProvider> codecs = getFormatConversionProviders();
for(int i=0; i<codecs.size(); i++ ) {
FormatConversionProvider codec = codecs.get(i);
if(codec.isConversionSupported(targetFormat, sourceFormat) ) {
return true;
}
}
return false;
}
/**
* Obtains an audio input stream of the indicated format, by converting the
* provided audio input stream.
*
* @param targetFormat the desired audio format after conversion
* @param sourceStream the stream to be converted
* @return an audio input stream of the indicated format
* @throws IllegalArgumentException if the conversion is not supported
* @throws NullPointerException if {@code targetFormat} or
* {@code sourceStream} are {@code null}
* @see #getTargetEncodings(AudioFormat)
* @see #getTargetFormats(AudioFormat.Encoding, AudioFormat)
* @see #isConversionSupported(AudioFormat, AudioFormat)
* @see #getAudioInputStream(AudioFormat.Encoding, AudioInputStream)
*/
public static AudioInputStream getAudioInputStream(AudioFormat targetFormat,
AudioInputStream sourceStream) {
if (sourceStream.getFormat().matches(targetFormat)) {
return sourceStream;
}
List<FormatConversionProvider> codecs = getFormatConversionProviders();
for(int i = 0; i < codecs.size(); i++) {
FormatConversionProvider codec = codecs.get(i);
if(codec.isConversionSupported(targetFormat,sourceStream.getFormat()) ) {
return codec.getAudioInputStream(targetFormat,sourceStream);
}
}
// we ran out of options...
throw new IllegalArgumentException("Unsupported conversion: " + targetFormat + " from " + sourceStream.getFormat());
}
/**
* Obtains the audio file format of the provided input stream. The stream
* must point to valid audio file data. The implementation of this method
* may require multiple parsers to examine the stream to determine whether
* they support it. These parsers must be able to mark the stream, read
* enough data to determine whether they support the stream, and reset the
* stream's read pointer to its original position. If the input stream does
* not support these operations, this method may fail with an
* {@code IOException}.
*
* @param stream the input stream from which file format information should
* be extracted
* @return an {@code AudioFileFormat} object describing the stream's audio
* file format
* @throws UnsupportedAudioFileException if the stream does not point to
* valid audio file data recognized by the system
* @throws IOException if an input/output exception occurs
* @throws NullPointerException if {@code stream} is {@code null}
* @see InputStream#markSupported
* @see InputStream#mark
*/
public static AudioFileFormat getAudioFileFormat(final InputStream stream)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(stream);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioFileFormat(stream);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("Stream of unsupported format");
}
/**
* Obtains the audio file format of the specified {@code URL}. The
* {@code URL} must point to valid audio file data.
*
* @param url the {@code URL} from which file format information should be
* extracted
* @return an {@code AudioFileFormat} object describing the audio file
* format
* @throws UnsupportedAudioFileException if the {@code URL} does not point
* to valid audio file data recognized by the system
* @throws IOException if an input/output exception occurs
* @throws NullPointerException if {@code url} is {@code null}
*/
public static AudioFileFormat getAudioFileFormat(final URL url)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(url);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioFileFormat(url);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("URL of unsupported format");
}
/**
* Obtains the audio file format of the specified {@code File}. The
* {@code File} must point to valid audio file data.
*
* @param file the {@code File} from which file format information should
* be extracted
* @return an {@code AudioFileFormat} object describing the audio file
* format
* @throws UnsupportedAudioFileException if the {@code File} does not point
* to valid audio file data recognized by the system
* @throws IOException if an I/O exception occurs
* @throws NullPointerException if {@code file} is {@code null}
*/
public static AudioFileFormat getAudioFileFormat(final File file)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(file);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioFileFormat(file);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("File of unsupported format");
}
/**
* Obtains an audio input stream from the provided input stream. The stream
* must point to valid audio file data. The implementation of this method
* may require multiple parsers to examine the stream to determine whether
* they support it. These parsers must be able to mark the stream, read
* enough data to determine whether they support the stream, and reset the
* stream's read pointer to its original position. If the input stream does
* not support these operation, this method may fail with an
* {@code IOException}.
*
* @param stream the input stream from which the {@code AudioInputStream}
* should be constructed
* @return an {@code AudioInputStream} object based on the audio file data
* contained in the input stream
* @throws UnsupportedAudioFileException if the stream does not point to
* valid audio file data recognized by the system
* @throws IOException if an I/O exception occurs
* @throws NullPointerException if {@code stream} is {@code null}
* @see InputStream#markSupported
* @see InputStream#mark
*/
public static AudioInputStream getAudioInputStream(final InputStream stream)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(stream);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioInputStream(stream);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("Stream of unsupported format");
}
/**
* Obtains an audio input stream from the {@code URL} provided. The
* {@code URL} must point to valid audio file data.
*
* @param url the {@code URL} for which the {@code AudioInputStream} should
* be constructed
* @return an {@code AudioInputStream} object based on the audio file data
* pointed to by the {@code URL}
* @throws UnsupportedAudioFileException if the {@code URL} does not point
* to valid audio file data recognized by the system
* @throws IOException if an I/O exception occurs
* @throws NullPointerException if {@code url} is {@code null}
*/
public static AudioInputStream getAudioInputStream(final URL url)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(url);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioInputStream(url);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("URL of unsupported format");
}
/**
* Obtains an audio input stream from the provided {@code File}. The
* {@code File} must point to valid audio file data.
*
* @param file the {@code File} for which the {@code AudioInputStream}
* should be constructed
* @return an {@code AudioInputStream} object based on the audio file data
* pointed to by the {@code File}
* @throws UnsupportedAudioFileException if the {@code File} does not point
* to valid audio file data recognized by the system
* @throws IOException if an I/O exception occurs
* @throws NullPointerException if {@code file} is {@code null}
*/
public static AudioInputStream getAudioInputStream(final File file)
throws UnsupportedAudioFileException, IOException {
Objects.requireNonNull(file);
for (final AudioFileReader reader : getAudioFileReaders()) {
try {
return reader.getAudioInputStream(file);
} catch (final UnsupportedAudioFileException ignored) {
}
}
throw new UnsupportedAudioFileException("File of unsupported format");
}
/**
* Obtains the file types for which file writing support is provided by the
* system.
*
* @return array of unique file types. If no file types are supported, an
* array of length 0 is returned.
*/
public static AudioFileFormat.Type[] getAudioFileTypes() {
List<AudioFileWriter> providers = getAudioFileWriters();
Set<AudioFileFormat.Type> returnTypesSet = new HashSet<>();
for(int i=0; i < providers.size(); i++) {
AudioFileWriter writer = providers.get(i);
AudioFileFormat.Type[] fileTypes = writer.getAudioFileTypes();
for(int j=0; j < fileTypes.length; j++) {
returnTypesSet.add(fileTypes[j]);
}
}
AudioFileFormat.Type returnTypes[] =
returnTypesSet.toArray(new AudioFileFormat.Type[0]);
return returnTypes;
}
/**
* Indicates whether file writing support for the specified file type is
* provided by the system.
*
* @param fileType the file type for which write capabilities are queried
* @return {@code true} if the file type is supported, otherwise
* {@code false}
* @throws NullPointerException if {@code fileType} is {@code null}
*/
public static boolean isFileTypeSupported(AudioFileFormat.Type fileType) {
Objects.requireNonNull(fileType);
List<AudioFileWriter> providers = getAudioFileWriters();
for(int i=0; i < providers.size(); i++) {
AudioFileWriter writer = providers.get(i);
if (writer.isFileTypeSupported(fileType)) {
return true;
}
}
return false;
}
/**
* Obtains the file types that the system can write from the audio input
* stream specified.
*
* @param stream the audio input stream for which audio file type support
* is queried
* @return array of file types. If no file types are supported, an array of
* length 0 is returned.
* @throws NullPointerException if {@code stream} is {@code null}
*/
public static AudioFileFormat.Type[] getAudioFileTypes(AudioInputStream stream) {
Objects.requireNonNull(stream);
List<AudioFileWriter> providers = getAudioFileWriters();
Set<AudioFileFormat.Type> returnTypesSet = new HashSet<>();
for(int i=0; i < providers.size(); i++) {
AudioFileWriter writer = providers.get(i);
AudioFileFormat.Type[] fileTypes = writer.getAudioFileTypes(stream);
for(int j=0; j < fileTypes.length; j++) {
returnTypesSet.add(fileTypes[j]);
}
}
AudioFileFormat.Type returnTypes[] =
returnTypesSet.toArray(new AudioFileFormat.Type[0]);
return returnTypes;
}
/**
* Indicates whether an audio file of the specified file type can be written
* from the indicated audio input stream.
*
* @param fileType the file type for which write capabilities are queried
* @param stream the stream for which file-writing support is queried
* @return {@code true} if the file type is supported for this audio input
* stream, otherwise {@code false}
* @throws NullPointerException if {@code fileType} or {@code stream} are
* {@code null}
*/
public static boolean isFileTypeSupported(AudioFileFormat.Type fileType,
AudioInputStream stream) {
Objects.requireNonNull(fileType);
Objects.requireNonNull(stream);
List<AudioFileWriter> providers = getAudioFileWriters();
for(int i=0; i < providers.size(); i++) {
AudioFileWriter writer = providers.get(i);
if(writer.isFileTypeSupported(fileType, stream)) {
return true;
}
}
return false;
}
/**
* Writes a stream of bytes representing an audio file of the specified file
* type to the output stream provided. Some file types require that the
* length be written into the file header; such files cannot be written from
* start to finish unless the length is known in advance. An attempt to
* write a file of such a type will fail with an {@code IOException} if the
* length in the audio file type is {@code AudioSystem.NOT_SPECIFIED}.
*
* @param stream the audio input stream containing audio data to be written
* to the file
* @param fileType the kind of audio file to write
* @param out the stream to which the file data should be written
* @return the number of bytes written to the output stream
* @throws IOException if an input/output exception occurs
* @throws IllegalArgumentException if the file type is not supported by the
* system
* @throws NullPointerException if {@code stream} or {@code fileType} or
* {@code out} are {@code null}
* @see #isFileTypeSupported
* @see #getAudioFileTypes
*/
public static int write(final AudioInputStream stream,
final AudioFileFormat.Type fileType,
final OutputStream out) throws IOException {
Objects.requireNonNull(stream);
Objects.requireNonNull(fileType);
Objects.requireNonNull(out);
for (final AudioFileWriter writer : getAudioFileWriters()) {
try {
return writer.write(stream, fileType, out);
} catch (final IllegalArgumentException ignored) {
// thrown if this provider cannot write the stream, try next
}
}
// "File type " + type + " not supported."
throw new IllegalArgumentException(
"could not write audio file: file type not supported: "
+ fileType);
}
/**
* Writes a stream of bytes representing an audio file of the specified file
* type to the external file provided.
*
* @param stream the audio input stream containing audio data to be written
* to the file
* @param fileType the kind of audio file to write
* @param out the external file to which the file data should be written
* @return the number of bytes written to the file
* @throws IOException if an I/O exception occurs
* @throws IllegalArgumentException if the file type is not supported by the
* system
* @throws NullPointerException if {@code stream} or {@code fileType} or
* {@code out} are {@code null}
* @see #isFileTypeSupported
* @see #getAudioFileTypes
*/
public static int write(final AudioInputStream stream,
final AudioFileFormat.Type fileType,
final File out) throws IOException {
Objects.requireNonNull(stream);
Objects.requireNonNull(fileType);
Objects.requireNonNull(out);
for (final AudioFileWriter writer : getAudioFileWriters()) {
try {
return writer.write(stream, fileType, out);
} catch (final IllegalArgumentException ignored) {
// thrown if this provider cannot write the stream, try next
}
}
throw new IllegalArgumentException(
"could not write audio file: file type not supported: "
+ fileType);
}
// METHODS FOR INTERNAL IMPLEMENTATION USE
/**
* Obtains the list of MixerProviders currently installed on the system.
*
* @return the list of MixerProviders currently installed on the system
*/
@SuppressWarnings("unchecked")
private static List<MixerProvider> getMixerProviders() {
return (List<MixerProvider>) getProviders(MixerProvider.class);
}
/**
* Obtains the set of format converters (codecs, transcoders, etc.) that are
* currently installed on the system.
*
* @return an array of {@link FormatConversionProvider} objects representing
* the available format converters. If no format converters readers
* are available on the system, an array of length 0 is returned.
*/
@SuppressWarnings("unchecked")
private static List<FormatConversionProvider> getFormatConversionProviders() {
return (List<FormatConversionProvider>) getProviders(FormatConversionProvider.class);
}
/**
* Obtains the set of audio file readers that are currently installed on the
* system.
*
* @return a List of {@link AudioFileReader} objects representing the
* installed audio file readers. If no audio file readers are
* available on the system, an empty List is returned.
*/
@SuppressWarnings("unchecked")
private static List<AudioFileReader> getAudioFileReaders() {
return (List<AudioFileReader>)getProviders(AudioFileReader.class);
}
/**
* Obtains the set of audio file writers that are currently installed on the
* system.
*
* @return a List of {@link AudioFileWriter} objects representing the
* available audio file writers. If no audio file writers are
* available on the system, an empty List is returned.
*/
@SuppressWarnings("unchecked")
private static List<AudioFileWriter> getAudioFileWriters() {
return (List<AudioFileWriter>)getProviders(AudioFileWriter.class);
}
/**
* Attempts to locate and return a default Mixer that provides lines of the
* specified type.
*
* @param providers the installed mixer providers
* @param info The requested line type TargetDataLine.class, Clip.class or
* Port.class
* @return a Mixer that matches the requirements, or null if no default
* mixer found
*/
private static Mixer getDefaultMixer(List<MixerProvider> providers, Line.Info info) {
Class<?> lineClass = info.getLineClass();
String providerClassName = JDK13Services.getDefaultProviderClassName(lineClass);
String instanceName = JDK13Services.getDefaultInstanceName(lineClass);
Mixer mixer;
if (providerClassName != null) {
MixerProvider defaultProvider = getNamedProvider(providerClassName, providers);
if (defaultProvider != null) {
if (instanceName != null) {
mixer = getNamedMixer(instanceName, defaultProvider, info);
if (mixer != null) {
return mixer;
}
} else {
mixer = getFirstMixer(defaultProvider, info,
false /* mixing not required*/);
if (mixer != null) {
return mixer;
}
}
}
}
/*
* - Provider class not specified, or
* - provider class cannot be found, or
* - provider class and instance specified and instance cannot be found
* or is not appropriate
*/
if (instanceName != null) {
mixer = getNamedMixer(instanceName, providers, info);
if (mixer != null) {
return mixer;
}
}
/*
* No defaults are specified, or if something is specified, everything
* failed
*/
return null;
}
/**
* Return a MixerProvider of a given class from the list of MixerProviders.
* This method never requires the returned Mixer to do mixing.
*
* @param providerClassName The class name of the provider to be returned
* @param providers The list of MixerProviders that is searched
* @return A MixerProvider of the requested class, or null if none is found
*/
private static MixerProvider getNamedProvider(String providerClassName,
List<MixerProvider> providers) {
for(int i = 0; i < providers.size(); i++) {
MixerProvider provider = providers.get(i);
if (provider.getClass().getName().equals(providerClassName)) {
return provider;
}
}
return null;
}
/**
* Return a Mixer with a given name from a given MixerProvider. This method
* never requires the returned Mixer to do mixing.
*
* @param mixerName The name of the Mixer to be returned
* @param provider The MixerProvider to check for Mixers
* @param info The type of line the returned Mixer is required to support
* @return A Mixer matching the requirements, or null if none is found
*/
private static Mixer getNamedMixer(String mixerName,
MixerProvider provider,
Line.Info info) {
Mixer.Info[] infos = provider.getMixerInfo();
for (int i = 0; i < infos.length; i++) {
if (infos[i].getName().equals(mixerName)) {
Mixer mixer = provider.getMixer(infos[i]);
if (isAppropriateMixer(mixer, info, false)) {
return mixer;
}
}
}
return null;
}
/**
* From a List of MixerProviders, return a Mixer with a given name. This
* method never requires the returned Mixer to do mixing.
*
* @param mixerName The name of the Mixer to be returned
* @param providers The List of MixerProviders to check for Mixers
* @param info The type of line the returned Mixer is required to support
* @return A Mixer matching the requirements, or null if none is found
*/
private static Mixer getNamedMixer(String mixerName,
List<MixerProvider> providers,
Line.Info info) {
for(int i = 0; i < providers.size(); i++) {
MixerProvider provider = providers.get(i);
Mixer mixer = getNamedMixer(mixerName, provider, info);
if (mixer != null) {
return mixer;
}
}
return null;
}
/**
* From a given MixerProvider, return the first appropriate Mixer.
*
* @param provider The MixerProvider to check for Mixers
* @param info The type of line the returned Mixer is required to support
* @param isMixingRequired If true, only Mixers that support mixing are
* returned for line types of SourceDataLine and Clip
* @return A Mixer that is considered appropriate, or null if none is found
*/
private static Mixer getFirstMixer(MixerProvider provider,
Line.Info info,
boolean isMixingRequired) {
Mixer.Info[] infos = provider.getMixerInfo();
for (int j = 0; j < infos.length; j++) {
Mixer mixer = provider.getMixer(infos[j]);
if (isAppropriateMixer(mixer, info, isMixingRequired)) {
return mixer;
}
}
return null;
}
/**
* Checks if a Mixer is appropriate. A Mixer is considered appropriate if it
* support the given line type. If isMixingRequired is {@code true} and the
* line type is an output one (SourceDataLine, Clip), the mixer is
* appropriate if it supports at least 2 (concurrent) lines of the given
* type.
*
* @param mixer The mixer to check
* @param lineInfo The line to check
* @param isMixingRequired Is the mixing required or not
* @return {@code true} if the mixer is considered appropriate according to
* the rules given above, {@code false} otherwise
*/
private static boolean isAppropriateMixer(Mixer mixer,
Line.Info lineInfo,
boolean isMixingRequired) {
if (! mixer.isLineSupported(lineInfo)) {
return false;
}
Class<?> lineClass = lineInfo.getLineClass();
if (isMixingRequired
&& (SourceDataLine.class.isAssignableFrom(lineClass) ||
Clip.class.isAssignableFrom(lineClass))) {
int maxLines = mixer.getMaxLines(lineInfo);
return ((maxLines == NOT_SPECIFIED) || (maxLines > 1));
}
return true;
}
/**
* Like getMixerInfo, but return List.
*
* @return a List of info objects for the currently installed mixers. If no
* mixers are available on the system, an empty List is returned.
* @see #getMixerInfo()
*/
private static List<Mixer.Info> getMixerInfoList() {
List<MixerProvider> providers = getMixerProviders();
return getMixerInfoList(providers);
}
/**
* Like getMixerInfo, but return List.
*
* @param providers The list of MixerProviders
* @return a List of info objects for the currently installed mixers. If no
* mixers are available on the system, an empty List is returned.
* @see #getMixerInfo()
*/
private static List<Mixer.Info> getMixerInfoList(List<MixerProvider> providers) {
List<Mixer.Info> infos = new ArrayList<>();
Mixer.Info[] someInfos; // per-mixer
Mixer.Info[] allInfos; // for all mixers
for(int i = 0; i < providers.size(); i++ ) {
someInfos = providers.get(i).getMixerInfo();
for (int j = 0; j < someInfos.length; j++) {
infos.add(someInfos[j]);
}
}
return infos;
}
/**
* Obtains the set of services currently installed on the system using the
* SPI mechanism in 1.3.
*
* @param providerClass The type of providers requested. This should be one
* of AudioFileReader.class, AudioFileWriter.class,
* FormatConversionProvider.class, MixerProvider.class,
* MidiDeviceProvider.class, MidiFileReader.class,
* MidiFileWriter.class or SoundbankReader.class.
* @return a List of instances of providers for the requested service. If no
* providers are available, a vector of length 0 will be returned.
*/
private static List<?> getProviders(Class<?> providerClass) {
return JDK13Services.getProviders(providerClass);
}
}