接收音量变化的广播信号

public class BroadCastTest extends AppCompatActivity {

        private  IntentFilter intentFilter;
        private NetWorkChangeReceiver networkChangeReceiver;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_broad_cast_test);
            intentFilter=new IntentFilter();
            intentFilter.addAction("android.media.VOLUME_CHANGED_ACTION");
            networkChangeReceiver=new NetWorkChangeReceiver();
            registerReceiver(networkChangeReceiver,intentFilter);
    }

    //动态注册,最后一定要销毁
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(networkChangeReceiver);
    }

    class NetWorkChangeReceiver extends BroadcastReceiver {
        @Override
        //接收到广播后,要执行的代码
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(context, "音量改变 ", Toast.LENGTH_LONG).show();
        }
    }
}