MidiUnavailableException在Java中？ [英] MidiUnavailableException in Java?

问题描述

我有一些麻烦，播放MIDI文件在Java中。我得到的是一个 MidiUnavailableException（MIDI OUT发射不可用）当我尝试播放它。我的code是标准的：

  {尝试
    midiseq = MidiSystem.getSequencer（）;
    midiseq.open（）;
    midiseq.setSequence（MidiSystem.getSequence（Sound1例子））;
    midiseq.setLoopCount（Sequencer.LOOP_CONTINUOUSLY）;
    midiseq.start（）;
}赶上（例外五）{e.printStackTrace（）;}
 

midiseq 是序; Sound1例子是的InputStream 。

这code适用于其他几台电脑，甚至是工作在Eclipse和JAR文件使用时，只是没有当我从命令提示符启动它。我下载了一个更稳定的Java MIDI应用程序，它抛出同样的异常。

这不可能是一个硬件问题，因为Eclipse可以运行没有问题的，既没有因为这可以正常运行在其他计算机上它可以是一个编码问题。即使code的这一行抛出此异常：

  javax.sound.midi.MidiSystem.getSequencer（）;
 

先谢谢了。

编辑：我的操作系统是Windows Vista中。之前我问这个问题我已经下载了最新的JRE和JDK（1.6.0_13我认为）。

编辑：code：

  ClassLoader.getSystemClassLoader（）的loadClass（com.sun.media.sound.RealTimeSequencer）;
的System.out.println（序类加载）; //否则的ClassNotFoundException
 

打印序类加载的。

但是，这code：

  {尝试
        的System.out.println（javax.sound.midi.MidiSystem.getSequencer（））;
        System.exit（0）;
      }赶上（例外五）{
        抛出新的RuntimeException（E）;
      }
      System.exit（1）;
 

投 MidiUnavailableException。

此外，这code：

  MidiDevice.Info [] =设备MidiSystem.getMidiDeviceInfo（）;
如果（devices.length == 0）{
的System.out.println（找不到MIDI设备）;
}其他{
对于（MidiDevice.Info开发：设备）{
的System.out.println（DEV）;
}
}
 

给我这样的：

    微软MIDI映射
    微软GS波形表合成器
    实时测序
    Java的声音合成器

解决方案

首先看一下你的系统的功能：

  MidiDevice.Info [] =设备MidiSystem.getMidiDeviceInfo（）;
如果（devices.length == 0）{
    的System.out.println（找不到MIDI设备）;
}其他{
    对于（MidiDevice.Info开发：设备）{
        的System.out.println（DEV）;
    }
}
 

如果有什么都没有，你可能需要安装音库以使
JVM来创建软件音序器。

另外，请检查MidiSystem.getReceiver（）的输出作为可怕MidiUnavailableException如果一个接收器无法创建也会发生（<一个href=\"http://java.sun.com/j2se/1.5.0/docs/api/javax/sound/midi/MidiSystem.html#getSequencer%28boolean%29\"相对=nofollow> MidiSystem的javadoc ）。

我希望安装音库文件将给JVM依傍合成接收器的机会，而不是需要硬件的访问了（这似乎是失败的：）

I'm having some trouble playing MIDI files in Java. What I get is a MidiUnavailableException (MIDI OUT transmitter not available) when I try to play it. My code is standard:

try {
    midiseq = MidiSystem.getSequencer();
    midiseq.open();
    midiseq.setSequence(MidiSystem.getSequence(sound1));
    midiseq.setLoopCount(Sequencer.LOOP_CONTINUOUSLY);
    midiseq.start();
} catch (Exception e) {e.printStackTrace();}

midiseq is a Sequencer; sound1 is an InputStream.

This code works on several other computers, and even works in Eclipse and when used in a JAR file, just not when I launch it from the command prompt. I've downloaded a more stable Java midi application, and it threw the same exception.

It can't be a hardware problem because Eclipse can run it without problems, neither can it be a coding problem because this runs correctly on other computers. Even this one line of code throws this exception:

javax.sound.midi.MidiSystem.getSequencer();

Thanks in advance.

edit: My operating system is Windows Vista. Before I asked this question I've downloaded the latest JRE and JDK (1.6.0_13 I think).

edit: The code:

ClassLoader.getSystemClassLoader().loadClass("com.sun.media.sound.RealTimeSequencer");
System.out.println( "Sequencer class loaded" );// Otherwise ClassNotFoundException

prints "Sequencer class loaded."

But this code:

  try{
        System.out.println(javax.sound.midi.MidiSystem.getSequencer());
        System.exit(0);
      } catch(Exception e) {
        throw new RuntimeException(e);
      }
      System.exit(1);

throws the MidiUnavailableException.

Also, this code:

	MidiDevice.Info[] devices = MidiSystem.getMidiDeviceInfo();
	if (devices.length == 0) {
	    System.out.println("No MIDI devices found");
	} else {
	    for (MidiDevice.Info dev : devices) {
	        System.out.println(dev);
	    }
	}

gives me this:

    Microsoft MIDI Mapper
    Microsoft GS Wavetable Synth
    Real Time Sequencer
    Java Sound Synthesizer

解决方案

First have a look at the capabilities of your system:

MidiDevice.Info[] devices = MidiSystem.getMidiDeviceInfo();
if (devices.length == 0) {
    System.out.println("No MIDI devices found");
} else {
    for (MidiDevice.Info dev : devices) {
        System.out.println(dev);
    }
}

If there is nothing there, you might need to install soundbanks to enable the jvm to create a software sequencer.

Also check the output of MidiSystem.getReceiver() as the dreaded MidiUnavailableException will also occur if a receiver can not be created (MidiSystem javadoc).

I expect that installing the soundbank file will give the jvm the opportunity to fall back on a synthesizer receiver, and not require hardware access anymore (which seems to fail:)

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