flutter can't import lpinyin.dart

[itlwy]

flutter can't import lpinyin.dart，error as below:

Try correcting the name to the name of an existing getter, or defining a getter or field named 'PinyinHelper'.
String pinyin = PinyinHelper.getPinyinE(user.userName);
^^^^^^^^^^^^
Unhandled exception:
FileSystemException(uri=org-dartlang-untranslatable-uri:package%3Alpinyin%2Flpinyin.dart; message=StandardFileSystem only supports file:*
and data:* URIs)
#0 StandardFileSystem.entityForUri (package:front_end/src/api_prototype/standard_file_system.dart:33:7)

#1 asFileUri (package:vm/kernel_front_end.dart:601:37)

#2
FrontendCompiler._outputDependenciesDelta (package:vm/frontend_server.dart:401:39)

#3 FrontendCompiler.compile (package:vm/frontend_server.dart:375:
13)

#4 _FlutterFrontendCompiler.compile (package:frontend_ser
ver/server.dart:31:22)

#5 starter (package:frontend_server/s
erver.dart:128:27)

#6 main (file:///C:/b/s/w/ir/k/src/flutter/frontend_ser
ver/bin/starter.dart:8:30)

#7 _startIsolate. (
dart:isolate-patch/isolate_patch.dart:299:32)
#8 _RawReceivePortImpl._handleMessage (dart:i
solate-patch/isolate_patch.dart:172:12)

[itlwy]

Flutter 1.7.8+hotfix.4
please help,thanks

[Sky24n]

Step 1：
dependencies:
  lpinyin: ^1.0.7

Step 2：
flutter packages get  
  
Step 3：
import 'package:lpinyin/lpinyin.dart';

String pinyin = PinyinHelper.getPinyinE(user.userName);