如何正确设置MediaPlayer的音频流类型 [英] How to correctly set MediaPlayer audio stream type

问题描述

我想创建一个方式来调整音量设置为每个不同的数据流（媒体，通知，铃声等）和有办法preVIEW每个流的输出音量。我相信我有正确执行，但是当我设置输出流类型，没有任何声音播放。

I'm trying to create a way to adjust volume settings for each of the different streams (media, notification, ringtone, etc) and have a way to preview the output sound level of each stream. I believe I have the correct implementation, but when I set the output stream type, there is no sound that plays.

下面是code，它可以正常播放用户选择的报警声：

Here is the code that correctly plays the user's selected alarm sound:

Uri mediaUri=RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
MediaPlayer mp=MediaPlayer.create(getApplicationContext(), mediaUri);
//mp.setAudioStreamType(AudioManager.STREAM_ALARM);
mp.start();`

这注释掉行是什么原因造成了我的问题。我想听到警报声在不同的音频流的音量电平，但是当我包括行STREAM_ALARM或任何其他音频流，根本没有声音播放。任何想法可能是怎么回事？

That commented out line is what is causing me problems. I would like to hear the alarm sound at the volume levels of the different audio streams, but when I include that line for STREAM_ALARM or any other audio stream, no sound at all plays. Any ideas what could be going on here?

推荐答案

好吧，我发现后，更多的测试解决方案，它看起来像这样，万一别人运行到同样的问题，我有。该MODIFY_AUDIO_SETTINGS权限需要在清单中的这个工作。

Okay, I found the solution after a bit more testing and it looks like this, in case anyone else runs into the same problem I was having. The MODIFY_AUDIO_SETTINGS permission is needed in the Manifest for this to work.

AudioManager am=(AudioManager)getSystemService(Context.AUDIO_SERVICE);
am.setMode(AudioManager.MODE_NORMAL);
MediaPlayer mp=new MediaPlayer();
Uri ringtoneUri=RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
try
{
    mp.setDataSource(getApplicationContext(), ringtoneUri);
    mp.setAudioStreamType(AudioManager.STREAM_NOTIFICATION);
    mp.prepare();
    mp.start();
}
catch(Exception e)
{
    //exception caught in the end zone
}

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