Java Sound 可以用来控制系统音量吗? [英] Can Java Sound be used to control the system volume?
问题描述
Java Sound 为各种声线功能提供 FloatControl
实例,以及 MASTER_GAIN
&VOLUME
控制类型.
Java Sound offers FloatControl
instances for various sound line functionality, and both a MASTER_GAIN
& VOLUME
control type.
这些控件可以用来改变系统音量吗?
Can these controls be used to change the system volume?
推荐答案
不,不能.这是改编自 Adjusting master volume 的答案的来源代码牧场.源代码迭代可用的行,检查它们是否具有正确类型的控件,如果是,则将它们放在附加到 JSlider
No, it cannot. Here is source adapted from an answer to Adjusting master volume on coderanch. The source iterates the available lines, checks if they have a control of the right type, and if so, puts them in a GUI attached to a JSlider
import java.awt.*;
import javax.swing.*;
import javax.sound.sampled.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class SoundMixer {
public Component getGui() {
JPanel gui = new JPanel(new GridLayout(0,1));
Mixer.Info[] mixers = AudioSystem.getMixerInfo();
System.out.println(
"There are " + mixers.length + " mixer info objects");
for (Mixer.Info mixerInfo : mixers) {
System.out.println("mixer name: " + mixerInfo.getName());
Mixer mixer = AudioSystem.getMixer(mixerInfo);
Line.Info[] lineInfos = mixer.getSourceLineInfo();
for (Line.Info lineInfo : lineInfos) {
System.out.println(" Line.Info: " + lineInfo);
try {
Line line = mixer.getLine(lineInfo);
FloatControl volCtrl = (FloatControl)line.getControl(
FloatControl.Type.MASTER_GAIN);
VolumeSlider vs = new VolumeSlider(volCtrl);
gui.add( new JLabel(volCtrl.toString()) );
gui.add( vs.getVolume() );
System.out.println(
" volCtrl.getValue() = " + volCtrl.getValue());
} catch (LineUnavailableException e) {
e.printStackTrace();
} catch (IllegalArgumentException iaEx) {
System.out.println(" " + iaEx);
}
}
}
return gui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
SoundMixer sm = new SoundMixer();
Component c = sm.getGui();
JOptionPane.showMessageDialog(null, c);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
SwingUtilities.invokeLater(r);
}
}
class VolumeSlider {
JSlider volume;
VolumeSlider(final FloatControl volumeControl) {
volume = new JSlider(
(int) volumeControl.getMinimum() * 100,
(int) volumeControl.getMaximum() * 100,
(int) volumeControl.getValue() * 100);
ChangeListener listener = new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
float val = volume.getValue() / 100f;
volumeControl.setValue(val);
System.out.println(
"Setting volume of " + volumeControl.toString() +
" to " + val);
}
};
volume.addChangeListener(listener);
}
public JSlider getVolume() {
return volume;
}
}
在这台 Windows 7 机器上,我得到了两个控件,都来自Java Sound Audio Engine".两者都对当前系统音量没有任何影响.
On this Windows 7 machine I get two controls, both from the "Java Sound Audio Engine". Neither has any effect on the current system volume.
run:
There are 4 mixer info objects
mixer name: Primary Sound Driver
Line.Info: interface SourceDataLine supporting 8 audio formats, and buffers of at least 32 bytes
java.lang.IllegalArgumentException: Unsupported control type: Master Gain
Line.Info: interface Clip supporting 8 audio formats, and buffers of at least 32 bytes
java.lang.IllegalArgumentException: Unsupported control type: Master Gain
mixer name: Speakers (VIA High Definition Audio)
Line.Info: interface SourceDataLine supporting 8 audio formats, and buffers of at least 32 bytes
java.lang.IllegalArgumentException: Unsupported control type: Master Gain
Line.Info: interface Clip supporting 8 audio formats, and buffers of at least 32 bytes
java.lang.IllegalArgumentException: Unsupported control type: Master Gain
mixer name: Java Sound Audio Engine
Line.Info: interface SourceDataLine supporting 8 audio formats
volCtrl.getValue() = 0.0
Line.Info: interface Clip supporting 8 audio formats, and buffers of 0 to 4194304 bytes
volCtrl.getValue() = 0.0
mixer name: Port Speakers (VIA High Definition A
Setting volume of Master Gain with current value: 0.0 dB (range: -80.0 - 13.9794) to 0.0
Setting volume of Master Gain with current value: 0.0 dB (range: -80.0 - 13.9794) to -0.41
Setting volume of Master Gain with current value: 0.0 dB (range: -80.0 - 13.9794) to -0.68
...
将 FloatControl.Type.MASTER_GAIN
换成 FloatControl.Type.VOLUME
以查看.. 没有控件.
Swap FloatControl.Type.MASTER_GAIN
for FloatControl.Type.VOLUME
to see.. no controls.
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