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Flutter Firebase性能-未处理的异常

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在跟踪HTTPMetric时出错。运行正常

检查以下追溯：

/flutter (10311): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(error,String index out of range: -1,null)
E/flutter (10311): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:569:7)
E/flutter (10311): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:316:33)
E/flutter (10311): <asynchronous suspension>
E/flutter (10311): #2      FirebasePerformance.newHttpMetric (package:firebase_performance/src/firebase_performance.dart:76:33)
E/flutter (10311): #3      _Client.send (package:<my_package>/api/api.dart:226:10)
E/flutter (10311): #4      _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:43:6)
E/flutter (10311): #5      _Client.send (package:<my_package>/api/api.dart:224:37)
E/flutter (10311): #6      Baseclient._sendUnstreamed (package:http/src/base_client.dart:169:38)
E/flutter (10311): #7      _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:43:6)
E/flutter (10311): #8      Baseclient._sendUnstreamed (package:http/src/base_client.dart:149:35)
E/flutter (10311): #9      Baseclient.post (package:http/src/base_client.dart:54:7)
E/flutter (10311): #10    MyAPI.post.<anonymous closure> (package:<my_package>/api/home.dart:17:33)
E/flutter (10311): #11     _asyncThenWrapperHelper.<anonymous closure> (dart:async-patch/async_patch.dart:71:64)
E/flutter (10311): #12     _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (10311): #13     _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (10311): #14     _FutureListener.handleValue (dart:async/future_impl.dart:137:18)
E/flutter (10311): #15     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:678:45)
E/flutter (10311): #16     Future._propagateToListeners (dart:async/future_impl.dart:707:32)
E/flutter (10311): #17     Future._completeWithValue (dart:async/future_impl.dart:522:5)
E/flutter (10311): #18     _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:30:15)
E/flutter (10311): #19     _completeonAsyncReturn (dart:async-patch/async_patch.dart:288:13)
E/flutter (10311): #20     BaseAPI.buildAuthHeaders (package:<my_package>/api/api.dart)
E/flutter (10311): #21     _asyncThenWrapperHelper.<anonymous closure> (dart:async-patch/async_patch.dart:71:64)
E/flutter (10311): #22     _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (10311): #23     _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (10311): #24     _FutureListener.handleValue (dart:async/future_impl.dart:137:18)
E/flutter (10311): #25     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:678:45)
E/flutter (10311): #26     Future._propagateToListeners (dart:async/future_impl.dart:707:32)
E/flutter (10311): #27     Future._completeWithValue (dart:async/future_impl.dart:522:5)
E/flutter (10311): #28     Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:552:7)
E/flutter (10311): #29     _rootRun (dart:async/zone.dart:1124:13)
E/flutter (10311): #30     _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter (10311): #31     _CustomZone.runGuarded (dart:async/zone.dart:923:7)
E/flutter (10311): #32     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:963:23)
E/flutter (10311): #33     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter (10311): #34     _startmicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
E/flutter (10311): 
I/flutter (10311): Error caught: MissingPluginException(No implementation found for method HttpMetric#start on channel plugins.flutter.io/firebase_performance)
I/flutter (10311): #0      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:314:7)
I/flutter (10311): <asynchronous suspension>
I/flutter (10311): #1      HttpMetric.start (package:firebase_performance/src/http_metric.dart:131:40)
I/flutter (10311): #2      _Client.send (package:<my_package>/api/api.dart:228:18)
I/flutter (10311): #3      _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:43:6)
I/flutter (10311): #4      _Client.send (<my_package>/api/api.dart:224:37)
I/flutter (10311): #5      Baseclient._sendUnstreamed (package:http/src/base_client.dart:169:38)
I/flutter (10311): #6      _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:43:6)
I/flutter (10311): #7      Baseclient._sendUnstreamed (package:http/src/base_client.dart:149:35)
I/flutter (10311): #8      Baseclient.post (package:http/src/base_client.dart:54:7)
I/flutter (10311): #9      MyAPI.post.<anonymous closure> (package<my_package>/api/home.dart:17:33)
I/flutter (10311): #10     _asyncThenWrapperHelper.<anonymous closure> (dart:async-patch/async_patch.dart:71:64)
I/flutter (10311): #11

以下是我的设置

abstract class BaseAPI {
  _Client client = _Client(http.Client());

  String encodeUrlParams(String url,Map<String,String> params) {
    Uri uri = Uri.parse(url);
    if (uri.hasQuery) params.addAll(uri.queryParameters);
    uri = uri.replace(queryParameters: params);
    return uri.toString();
  }

  String appendPath(String url,List pathSegments) {
    final pathSeg = pathSegments.map((ps) => ps.toString()).join("/");
    return url.endsWith("/") ? "$url$pathSeg/" : "$url/$pathSeg/";
  }

  Map<String,String> buildBasicHeaders() {
    return {
      HttpHeaders.contentTypeHeader: "application/json",HttpHeaders.acceptheader: "application/json",};
  }
}

class _Client extends http.Baseclient {
  _Client(this._inner);

  final http.Client _inner;

  HttpMethod _nameToEnum(String methodName) {
    switch (methodName) {
      case "GET":
        return HttpMethod.Get;
      case "POST":
        return HttpMethod.Post;
      case "HEAD":
        return HttpMethod.Head;
      case "PUT":
        return HttpMethod.Put;
      case "DELETE":
        return HttpMethod.Delete;
      default:
        return HttpMethod.Get;
    }
  }

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) async {
    final HttpMetric metric = FirebasePerformance.instance
        .newHttpMetric(request.url.toString(),_nameToEnum(request.method));

    await metric.start();

    http.StreamedResponse response;
    try {
      response = await _inner.send(request);
      metric
        ..responsePayloadSize = response.contentLength
        ..responseContentType = response.headers['Content-Type']
        ..requestPayloadSize = request.contentLength
        ..httpResponseCode = response.statusCode;
    } finally {
      await metric.stop();
    }

    return response;
  }
}

之前它运行正常，突然抛出了此错误。

zuiainibaonei 回答：Flutter Firebase性能-未处理的异常

这是已知问题：https://github.com/FirebaseExtended/flutterfire/issues/1136

正在发生这种情况，因为URL以“？”结尾。按照建议删除它可以解决问题。

来自问题：

  

要删除结尾吗？解决问题

     
    var strUri = request.url.toString();
    strUri = strUri.endsWith("?") ? strUri.substring(0,strUri.length - 1): strUri;

    final HttpMetric metric = FirebasePerformance.instance.newHttpMetric(strUri,...); ```

对于有问题的代码，解决方案应为：

String encodeUrlParams(String url,Map<String,dynamic> params) {
    Uri uri = Uri.parse(url);
    if (uri.hasQuery) params.addAll(uri.queryParameters);
    uri = uri.replace(queryParameters: params);
    final uriStr = uri.toString();
    return uriStr.endsWith("?")
        ? uriStr.substring(0,uriStr.length - 1)
        : uriStr;
  }
firebasefirebase-performanceflutter
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