private class BatteryLevelReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {
                Log.d(TAG, "收到了电量变化的广播   action is  ---" + action);
                Log.d(TAG, "当前电量 ：" + intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0));
                if (textView != null) {
                    textView.setText("当前电量：" + intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0));
                }
            } else if (Intent.ACTION_POWER_CONNECTED.equals(action)) {
                Log.d(TAG, "USB线连接上了。。。");
                Toast.makeText(MainActivity.this, "USB线连接了。。。", Toast.LENGTH_SHORT).show();
            } else if (Intent.ACTION_POWER_DISCONNECTED.equals(action)) {
                Log.d(TAG, "USB线断开了。。。");
                Toast.makeText(MainActivity.this, "USB线断开了。。。", Toast.LENGTH_SHORT).show();
            }
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (receiver != null) {
            this.unregisterReceiver(receiver);
        }
    }
}

就是跟锯老师写的一毛一样的，就是监听不了 Intent.ACTION_POWER_DISCONNECTED。

用了TOAST也不显示，看了好久，代码没问题，Logcat 代替之显示的是以下信息：

2020-08-29 15:36:40.929 8478-8497/com.example.batterylevel D/EGL_emulation: eglMakeCurrent: 0xb1305060: ver 3 1 (tinfo 0xb13031e0)