很长一段时间以来，我一直在尝试让 midi 音量控制在 MidiPlayer 类中工作。我已经在 stackoverflow 和整个 Internet 上搜索了完成此操作的示例，但我尝试的任何方法似乎都不起作用。音量保持不变！它不会像我想要的那样改变。
我在 Windows 7 专业版上运行 Java 1.6.0_32。
这里！拥有 SSCCE：
import java.io.*;
import javax.sound.midi.*;
import java.net.URL;
public class MidiSSCCE {
public static void main(String[] args)
{
// creates the midi player and sets up its sequencer and synthesizer.
MidiPlayer midiP = new MidiPlayer();
double volume = 1.0;
// loads a midi from a url into the sequencer, but doesn't start playing it yet.
midiP.load("http://www.vgmusic.com/music/computer/microsoft/windows/touhou_6_stage3_boss.mid",true);
// set the midi to loop indefinitely.
midiP.loop(-1);
// start playing the midi.
midiP.play(true);
// while loop changes the volume of the midi while it is playing.
while(true) {
midiP.setVolume(volume);
try { Thread.sleep(300); } catch(Exception e) {}
volume -= 0.1;
if(volume < 0) volume += 1.0;
}
}
}
/**
* MidiPlayer
* author: Stephen Lindberg
* Last modified: Oct 14, 2011
*
* A class that allows midi files to be loaded and played.
**/
class MidiPlayer {
private Sequence seq;
private Sequencer seqr;
private Synthesizer synth;
private Receiver receiver;
private File midiFile;
private String midiID;
private boolean loaded;
private boolean usingHardwareSoundbank;
// CONSTRUCTORS
public MidiPlayer() {
loaded = false;
try {
// obtain the sequencer and synthesizer.
seqr = MidiSystem.getSequencer();
synth = MidiSystem.getSynthesizer();
// print the user's midi device info
System.out.println("Setting up Midi Player...");
System.out.println("MidiDeviceInfo: ");
for(MidiDevice.Info info : MidiSystem.getMidiDeviceInfo()) {
System.out.println("\t" + info.getName() + ": " +info.getDescription());
}
System.out.println();
// obtain the soundbank and receiver.
Soundbank soundbank = synth.getDefaultSoundbank();
if(soundbank == null) {
receiver = MidiSystem.getReceiver();
usingHardwareSoundbank = true;
System.out.println("using hardware soundbank");
}
else {
synth.loadAllInstruments(soundbank);
receiver = synth.getReceiver();
usingHardwareSoundbank = false;
System.out.println("using default software soundbank:" + soundbank);
}
seqr.getTransmitter().setReceiver(receiver);
}
catch(Exception e) {
System.out.println("MIDI error: I just don't know what went wrong! 6_9");
}
}
// DATA METHODS
/**
* load(String fileName)
* loads a midi file into this MidiPlayer.
* Preconditions: fileName is the name of the midi file to be loaded.
* Postconditions: fileName is loaded and is ready to be played.
**/
public void load(String fileName, boolean isOnline) {
this.unload();
try {
URL midiURL;
if(isOnline) midiURL = new URL(fileName);
else midiURL = getClass().getClassLoader().getResource(fileName);
seq = MidiSystem.getSequence(midiURL);
seqr.open();
synth.open();
// load our sequence into the sequencer.
seqr.setSequence(seq);
loaded = true;
}
catch(IOException ioe) {
System.out.println("MIDI error: Problem occured while reading " + midiFile.getName() + ".");
}
catch(InvalidMidiDataException imde) {
System.out.println("MIDI error: " + midiFile.getName() + " is not a valid MIDI file or is unreadable.");
}
catch(Exception e) {
System.out.println("MIDI error: I just don't know what went wrong! 6_9");
}
}
/**
* unload()
* Unloads the current midi from the MidiPlayer and releases its resources from memory.
**/
public void unload() {
this.stop();
seqr.close();
synth.close();
midiFile = null;
loaded = false;
}
// OTHER METHODS
/**
* play(boolean reset)
* plays the currently loaded midi.
* Preconditions: reset tells our midi whether or nor to begin playing from the start of the midi file's current loop start point.
* Postconditions: If reset is true, then the loaded midi begins playing from its loop start point (default 0).
* If reset is false, then the loaded midi resumes playing from its current position.
**/
public void play(boolean reset) {
if(reset) seqr.setTickPosition(seqr.getLoopStartPoint());
seqr.start();
}
/**
* stop()
* Pauses the current midi if it was playing.
**/
public void stop() {
if(seqr.isOpen()) seqr.stop();
}
/**
* isRunning()
* Returns true if the current midi is playing. Returns false otherwise.
**/
public boolean isRunning() {
return seqr.isRunning();
}
/**
* loop(int times)
* Sets the current midi to loop from start to finish a specific number of times.
* Preconditions: times is the number of times we want our midi to loop.
* Postconditions: The current midi is set to loop times times.
* If times = -1, the current midi will be set to loop infinitely.
**/
public void loop(int times)
{
loop(times,0,-1);
}
/**
* loop(int times)
* Sets the current midi to loop from a specified start point to a specified end point a specific number of times.
* Preconditions: times is the number of times we want our midi to loop.
* start is our loop's start point in ticks.
* end is our loop's end point in ticks.
* Postconditions: The current midi is set to loop from tick start to tick end times times.
* If times = -1, the current midi will be set to loop infinitely.
**/
public void loop(int times, long start, long end) {
if(start < 0) start = 0;
if(end > seqr.getSequence().getTickLength() || end <= 0) end = seqr.getSequence().getTickLength();
if(start >= end && end != -1) start = end-1;
seqr.setLoopStartPoint(start);
seqr.setLoopEndPoint(end);
if(times == -1) seqr.setLoopCount(Sequencer.LOOP_CONTINUOUSLY);
else seqr.setLoopCount(times);
}
public void setVolume(double vol) {
System.out.println("Midi volume change request: " + vol);
try {
if(usingHardwareSoundbank) {
ShortMessage volumeMessage = new ShortMessage();
for ( int i = 0; i < 16; i++ ) {
volumeMessage.setMessage( ShortMessage.CONTROL_CHANGE, i, 7, (int)(vol*127) );
receiver.send( volumeMessage, -1 );
}
}
else {
MidiChannel[] channels = synth.getChannels();
for( int c = 0; c < channels.length; c++ ) {
if(channels[c] != null) channels[c].controlChange( 7, (int)( vol*127) );
}
}
}
catch ( Exception e ) {
e.printStackTrace();
}
}
}
我在以下来源尝试了示例但没有成功：
http://www.java2s.com/Code/Java/Development-Class/SettingtheVolumeofPlayingMidiAudio.htm
https://forums.oracle.com/forums/thread.jspa?messageID=5389030
http://www.codezealot.org/archives/27
http://www.exampledepot.com/egs/javax.sound.midi/Volume.html