Flutter NFC:如何防止/阻止“扫描新标签"Flutter Android Build中的默认活动? [英] Flutter NFC: How to prevent/stop "New Tag Scanned" default activity in Flutter Android Build?

问题描述

每个人我正在使用NFC插件"nfc_in_flutter"在我的flutter应用程序中，但是我面对的是已扫描新标签"android版本中的问题.每当我扫描标签时，第一次运行都很好，但是第二次自动/默认情况下，新标签已扫描"会自动运行.活动已打开.

Everyone I'm using NFC plugin "nfc_in_flutter" in my flutter app but I'm facing "New Tag Scanned" issue in android build. Whenever I scan tag, First time, it works good but on second time automatically/bydefault "New Tag Scanned" activity open.

这是我的代码:

Future<String> _nFCscan() async {
    String nfcdataString = "";
    setState(() {
      _inAsyncCall = true;
    });
    try {
      NDEFMessage message = await NFC
          .readNDEF(once: true, readerMode: NFCDispatchReaderMode())
          .timeout(Duration(seconds: 10))
          .first;
      if (message != null && message.payload != '') {
        setState(() => nfcdataString = message.data);
      }
    } on PlatformException catch (e) {
      if (e.code == BarcodeScanner.cameraAccessDenied) {
        Fluttertoast.showToast(
          msg: 'The user has\'t granted permission to the camera!',
        );
      } else {
        Fluttertoast.showToast(
          msg: 'Unknown error: ' + "$e",
        );
      }
    } on FormatException {} catch (e) {}

    setState(() {
      _inAsyncCall = false;
    });

    print(nfcdataString);
    if (nfcdataString != null) {
      return nfcdataString;
    } else {
      Fluttertoast.showToast(
        msg: 'NFC data issue',
      );
      return null;
    }
  }

Android Manifest.xml:

Android Manifest.xml:

  <intent-filter>
          <action android:name="android.nfc.action.NDEF_DISCOVERED" />
          <category android:name="android.intent.category.DEFAULT" />
          <data android:scheme="*" />
  </intent-filter>


 <uses-permission android:name="android.permission.NFC" /> 
    <uses-feature android:name="android.hardware.nfc" android:required="false" />

推荐答案

您已将该插件配置为仅读取一张卡

You have configured the plugin to only read one card

尝试更改 .readNDEF(一次:true，readerMode:NFCDispatchReaderMode())

到 .readNDEF(一次:false，readerMode:NFCDispatchReaderMode())

因此您不要求插件仅读取一张卡.

so you don't ask the plugin to only read one card.

更新

我不是专家，但是在 await 上使用 timeout 和 first 意味着您将取消等待标签的操作10秒，仅在取消等待NFC事件之前等待第一个事件.这两个原因可能是它仅对第一张NFC卡做出响应的原因.

I'm not a flutter expert but the use of timeout and first on the await means you will cancel waiting for a tag after 10 seconds and only wait for the first event before cancelling waiting for NFC events. Both of these might be a reason why it only responds to the first NFC card.

这篇关于Flutter NFC:如何防止/阻止“扫描新标签"Flutter Android Build中的默认活动?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！