更改连接时在来自BroadcastReceiver的活动消息中显示

// 在活动中注册BroadcastReceiver
private BroadcastReceiver networkChangeReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // 获取网络连接状态的变化
        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        
        // 判断网络连接状态
        if (networkInfo != null && networkInfo.isConnected()) {
            // 网络已连接
            Toast.makeText(context, "网络已连接", Toast.LENGTH_SHORT).show();
        } else {
            // 网络未连接
            Toast.makeText(context, "网络未连接", Toast.LENGTH_SHORT).show();
        }
    }
};

@Override
protected void onResume() {
    super.onResume();
    // 注册BroadcastReceiver
    IntentFilter intentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
    registerReceiver(networkChangeReceiver, intentFilter);
}

@Override
protected void onPause() {
    super.onPause();
    // 取消注册BroadcastReceiver
    unregisterReceiver(networkChangeReceiver);
}