新的项目需要监听android声音的变化，再做出对应的操作，从网上找了个demo验证。记录于此。

参考链接

https://my.oschina.net/yuanxulong/blog/372268

package com.example.volumetest;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.media.AudioManager;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    AudioManager audioManager;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        audioManager = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE);

        myRegisterReceiver();

    }

    private void myRegisterReceiver() {

        MyVolumeReceiver mVolumeReceiver = new MyVolumeReceiver();

        IntentFilter filter = new IntentFilter();

        filter.addAction("android.media.VOLUME_CHANGED_ACTION");

        registerReceiver(mVolumeReceiver, filter);

    }

    private class MyVolumeReceiver extends BroadcastReceiver {

        @Override

        public void onReceive(Context context, Intent intent) {

            if (intent.getAction().equals("android.media.VOLUME_CHANGED_ACTION")) {

                int currVolume = audioManager.getStreamVolume(AudioManager.STREAM_SYSTEM);

                //int currVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);

                Toast.makeText(getApplicationContext(), currVolume + "", Toast.LENGTH_SHORT).show();

            }

        }

    }

}

一开始通过按键调整的是系统声音STREAM_SYSTEM，读取的是STREAM_MUSIC。一直读取不到数据，更改之后就可以了。

STREAM_ALARM 警报

STREAM_MUSIC 音乐回放即媒体音量

STREAM_NOTIFICATION 窗口顶部状态栏Notification,

STREAM_RING 铃声

STREAM_SYSTEM 系统

STREAM_VOICE_CALL 通话

STREAM_DTMF 双音多频,不是很明白什么东西

Tony Liu

2017-5-9, Shenzhen