很多同学可能在flutter中国网站上学习的时候，创建了cacheConfig.json、profile.json、repo.json、user.json等json的时候，然后再执行  flutter packages pub run json_model就报错，报错信息如下：

Unhandled exception:
FormatException: Unexpected character (at line 2, character 18)
  "enable":true, // 是否启用缓存
                 ^

#0      _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1392:5)
#1      _ChunkedJsonParser.parse (dart:convert-patch/convert_patch.dart:922:48)
#2      _parseJson (dart:convert-patch/convert_patch.dart:29:10)
#3      JsonDecoder.convert (dart:convert/json.dart:493:36)
#4      JsonCodec.decode (dart:convert/json.dart:151:41)
#5      walk.<anonymous closure> (file:///D:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/json_model-0.0.2/bin/json_model.dart:46:22)
#6      List.forEach (dart:core-patch/growable_array.dart:283:8)
#7      walk (file:///D:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/json_model-0.0.2/bin/json_model.dart:38:8)
#8      main (file:///D:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/json_model-0.0.2/bin/json_model.dart:18:6)
#9      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:303:32)
#10     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12)
 

解决办法：

去掉json中所有的注释后再执行：flutter packages pub run json_model