简单地说，我在我的应用程序中使用 .ogg 文件，我需要循环播放几个背景音轨。
但是，我循环播放音频文件的方法只是重新加载音频文件并再次播放。这种方法会在每次循环播放之间产生延迟，这对于游戏所期望的无缝体验来说是不理想的。
有没有办法我不必每次都重新加载文件？如有必要，我愿意将音频文件保存在内存中。
这是我的 Sound 类，其功能有所减少，可以解决问题的核心：
import static javax.sound.sampled.AudioFormat.Encoding.PCM_SIGNED;
import static javax.sound.sampled.AudioSystem.getAudioInputStream;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine.Info;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
import javax.sound.sampled.UnsupportedAudioFileException;
/**
* The {@code Sound} class plays audio from a wav, ogg, or mp3 file with wav working the best in a new thread
* <p>
* Here are some examples of how the {@code Sound} object can be initialized:
* <blockquote><pre>
* Sound soundOne = new Sound("pathToFile/music.wav", true);
* Sound soundTwo = new Sound(new File("pathToFile/music.wav"), true);
* Sound soundThree = new Sound(ClassName.class.getResource(pathToFile/music.wav), true);
* </pre></blockquote>
* <p>
* The class {@code Sound} includes methods for playing audio, stopping audio, changing the volume, getting the duration if a wav, get whether the
* audio is stopped, get whether the audio is finished, and changing the input file
*
* @author Gigi Bayte 2
*/
public class Sound {
/**
* Whether or not the music should be playing in a loop
*/
private boolean loopable;
/**
* The String name of the file
*/
private String fileName;
/**
* The list of instances of this sound playing
*/
private ArrayList<PlayingSound> playingSounds = new ArrayList<>();
/**
* Initializes a newly created {@code Sound} object given a String file name
*
* @param fileName Path of the file to be played
* @param loopable Whether or not the audio should loop
*/
public Sound(String fileName, boolean loopable) {
this.fileName = fileName;
this.loopable = loopable;
}
/**
* Plays the audio from the given source
*/
public final void play() {
playingSounds.add(new PlayingSound());
}
/**
* Stops the audio from playing
*/
public final void stop() {
for(PlayingSound ps : playingSounds)
ps.stop();
}
/**
* The AudioFormat to specify the convention to represent the data
*
* @param inFormat The format of the audio file
* @return The necessary format information from the inFormat
*/
private AudioFormat getOutFormat(AudioFormat inFormat) {
final int ch = inFormat.getChannels();
final float rate = inFormat.getSampleRate();
return new AudioFormat(PCM_SIGNED, rate, 16, ch, ch * 2, rate, false);
}
/**
* Removes a {@code PlayingSound} object from the {@code ArrayList} of audio clips playing
*
* @param ps The {@code PlayingSound} instance to remove
*/
private void removeInternalSound(PlayingSound ps) {
playingSounds.remove(ps);
}
/**
* The {@code PlayingSound} class plays the audio file and allows for multiple files to be played and stopped
*/
private class PlayingSound {
private boolean stop = false;
PlayingSound() {
Thread playingSound = new Thread(() -> {
do {
try {
AudioInputStream in;
in = getAudioInputStream(new File(fileName));
final AudioFormat outFormat = getOutFormat(in.getFormat());
final Info info = new Info(SourceDataLine.class, outFormat);
try(final SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info)) {
if(line != null) {
line.open(outFormat);
line.start();
AudioInputStream inputMystream = AudioSystem.getAudioInputStream(outFormat, in);
stream(inputMystream, line);
line.drain();
line.stop();
}
}
}
catch(UnsupportedAudioFileException | LineUnavailableException | IOException e) {
throw new IllegalStateException(e);
}
} while(loopable && !stop);
removeInternalSound(this);
});
playingSound.start();
}
/**
* Streams the audio to the mixer
*
* @param in Input stream to audio file
* @param line Where the audio data can be written to
* @throws IOException Thrown if given file has any problems
*/
private void stream(AudioInputStream in, SourceDataLine line) throws IOException {
byte[] buffer = new byte[32];
for(int n = 0; n != -1 && !stop; n = in.read(buffer, 0, buffer.length)) {
byte[] bufferTemp = new byte[buffer.length];
for(int i = 0; i < bufferTemp.length; i += 2) {
short audioSample = (short) ((short) ((buffer[i + 1] & 0xff) << 8) | (buffer[i] & 0xff));
bufferTemp[i] = (byte) audioSample;
bufferTemp[i + 1] = (byte) (audioSample >> 8);
}
buffer = bufferTemp;
line.write(buffer, 0, n);
}
}
void stop() {
stop = true;
}
}
}
以下库可能是播放某些文件类型所必需的，应与上述文件一起编译：（链接）
对于未来的读者，以防上述链接过期，使用的库如下：
- jl1.0.1.jar
- 慢跑-0.0.7.jar
- jobis-0.0.17-1.jar
- mp3spi1.9.5.jar
- vorbisspi1.0.3.jar
使用这个 Sound 类和这个 ogg 文件（Undertale 中的 Spear of Justice），这是一个显示问题的简单类：
import javax.sound.sampled.UnsupportedAudioFileException;
import java.io.IOException;
public class Test {
public static void main(String[] args) throws IOException, UnsupportedAudioFileException, InterruptedException {
//Replace the path with the path to the downloaded soj.ogg file or another test file
Sound spearOfJustice = new Sound("C:\\Users\\gigibayte\\Desktop\\soj.ogg", true);
spearOfJustice.play();
//Ensure that this is greater than or equal than the length of the audio file chosen above in seconds.
int songSeconds = 240;
//Song is played twice to show looping issue
Thread.sleep(songSeconds * 2 * 1000);
}
}