我正在尝试读取UDP数据并将其转换为float。
我知道我需要
这是损坏的代码:
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);
});
});
}
这是调试代码:
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
nc -u 192.168.1.1 4444
初始化netcat并发送数据“1111”,则会从调试代码中打印出以下内容:[49, 49, 49, 49, 10]
我知道这些值是assai字符“1111”,后跟回车符。
问题是,当我运行“代码破损”时,最终收到以下消息:
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,当我不使用字符串或asByteData命令时为什么会出现错误
Class 'String' has no instance method 'asByteData'
?我一直在使用以下文档:Dart - ByteData
谢谢
最佳答案
调用堆栈显示了这里发生的事情:
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)
您正在调用
new ByteData.view
,而在内部调用asByteData
。ByteData.view
构造函数采用ByteBuffer
,但您正在将其传递给字符串:ByteBuffer buffer = getTypeName(d.data.buffer);
尽管您在此处编写了
ByteBuffer
,但是getTypeName()
函数实际上返回的是String
:return reflect(obj).type.reflectedType.toString();