为什么bytedata.view(buffer)抛出nosuchmethoderror:class'string'没有实例方法'asbytedata'

我正在尝试读取udp数据并将其转换为浮点。

我知道我需要

1. 从rawdatagramsocket接收数据报
2. 从数据报中获取bytebuffer
3. 将bytebuffer转换为bytedata
4. 对bytedata使用getfloat32方法

这是坏代码:

import 'dart:io';
import 'dart:typed_data';
import 'dart:mirrors';

getTypeName(dynamic obj) {
  return reflect(obj).type.reflectedType.toString();
}

void main(List<String> args){
  RawDatagramSocket.bind("192.168.1.1", 4444).then((RawDatagramSocket socket){
    print('Datagram socket ready to receive');
    print('${socket.address.address}:${socket.port}');
    socket.listen((RawSocketEvent e){
      Datagram d = socket.receive();
      if (d == null) return;
      ByteBuffer buffer = getTypeName(d.data.buffer);
      ByteData bdata = new ByteData.view(buffer);
    });
  });
}

下面是调试代码:

import 'dart:io';
import 'dart:typed_data';
import 'dart:mirrors';

getTypeName(dynamic obj) {
  return reflect(obj).type.reflectedType.toString();
}

void main(List<String> args){
  RawDatagramSocket.bind("192.168.1.1", 4444).then((RawDatagramSocket socket){
    print('Datagram socket ready to receive');
    print('${socket.address.address}:${socket.port}');
    socket.listen((RawSocketEvent e){
      Datagram d = socket.receive();
      if (d == null) return;
      print(d.data);
    });
  });
}

如果我使用以下命令启动netcat nc -u 192.168.1.1 4444 然后发送数据“1111”,我从调试代码中得到以下输出:

[49, 49, 49, 49, 10]

我知道这些值是“1111”的assai字符,后跟回车。

问题是,当我运行“坏代码”时,我最终得到以下消息:

Unhandled exception:
NoSuchMethodError: Class 'String' has no instance method 'asByteData'.
Receiver: "_ByteBuffer"
Tried calling: asByteData(0, null)
#0      Object._noSuchMethod (dart:core-patch/object_patch.dart:43)
#1      Object.noSuchMethod (dart:core-patch/object_patch.dart:47)
#2      new ByteData.view (dart:typed_data:449)
#3      main.<anonymous closure>.<anonymous closure> (file:///Users/iProgram/test.dart:17:25)
#4      _RootZone.runUnaryGuarded (dart:async/zone.dart:1307)
#5      _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:330)
#6      _BufferingStreamSubscription._add (dart:async/stream_impl.dart:257)
#7      _StreamController&&_SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:796)
#8      _StreamController._add (dart:async/stream_controller.dart:667)
#9      _StreamController.add (dart:async/stream_controller.dart:613)
#10     new _RawDatagramSocket.<anonymous closure> (dart:io-patch/socket_patch.dart:1699)
#11     _NativeSocket.issueReadEvent.issue (dart:io-patch/socket_patch.dart:760)
#12     _microtaskLoop (dart:async/schedule_microtask.dart:41)
#13     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#14     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:99)
#15     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:152)

问题是,我为什么会犯错 Class 'String' has no instance method 'asByteData' 当我不使用字符串或asbytedata命令时?

我一直在使用以下文档: Dart - ByteData

谢谢