您需要在其中BroadcastReciever正在提供上下文传递（你不能使用这个 ）

You need to pass in the context in which the BroadcastReciever is supplying (you can't use this)

//---display the new SMS message---
Toast.makeText(context, str, Toast.LENGTH_SHORT).show();
if(testString.equals("#silent"))
{   
    intent.putExtra(EXTRA_MESSAGE, SILENT_MESSAGE);
    AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    am.setRingerMode(AudioManager.RINGER_MODE_SILENT);
}   
else if(testString.equals("#volume"))
{   
    AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    am.setRingerMode(AudioManager.RINGER_MODE_NORMAL);
    intent.putExtra(EXTRA_MESSAGE, VOLUME_MESSAGE);
}