dio put操作无法正常工作

Question

我正在尝试使用休息中心 api 将 flutter web 应用程序与 mongodb 连接起来。 在 mongoDB 中创建新集合需要 PUT 操作。 我检查了 Postman 中的请求，它工作正常。 我可以从已经存在的集合中获取数据（GET、POST 工作正常）。

代码：

Dio dio = new Dio();
  dio.interceptors.add(InterceptorsWrapper(onRequest:
   (RequestOptions options) async {
    var customHeaders = {
      'content-type': 'application/json',
      HttpHeaders.authorizationHeader: "Basic $encoded"
    };
    options.headers.addAll(customHeaders);
    return options;      
  }));  
  String url = "http://localhost:8080/toofo";
  response2 = await dio.put(url);
  print("############## ${response2.statusCode} ##########");
  print("############## ${response2.data} ##########");

错误：

 Error: DioError [DioErrorType.RESPONSE]: XMLHttpRequest error.
    at Object.throw_ [as throw] (http://localhost:52789/dart_sdk.js:4773:11)
    at dio_for_browser.DioForBrowser.new.<anonymous> (http://localhost:52789/packages/dio/src/entry/dio_for_browser.dart.lib.js:359:27)
    at Generator.next (<anonymous>)
    at onValue (http://localhost:52789/dart_sdk.js:35655:33)
    at _RootZone.runUnary (http://localhost:52789/dart_sdk.js:35540:58)
    at _FutureListener.thenAwait.handleValue (http://localhost:52789/dart_sdk.js:30956:29)
    at handleValueCallback (http://localhost:52789/dart_sdk.js:31466:49)
    at Function._propagateToListeners (http://localhost:52789/dart_sdk.js:31498:17)
    at _Future.new.[_completeWithValue] (http://localhost:52789/dart_sdk.js:31357:23)
    at async._AsyncCallbackEntry.new.callback (http://localhost:52789/dart_sdk.js:31377:35)
    at Object._microtaskLoop (http://localhost:52789/dart_sdk.js:35756:13)
    at _startMicrotaskLoop (http://localhost:52789/dart_sdk.js:35762:13)

我还在 flutter 中尝试了 http package，得到了类似的错误。

这是 PUT 请求201Created的邮递员状态

Answer 1

交叉原点出现 XMLHttpRequest 错误。 使用此监听器

  headers: {
  'content-type': 'application/json',
 "Access-Control-Allow-Origin": "*", // Required for CORS support to work
 "Access-Control-Allow-Credentials": true, // Required for cookies, authorization   headers with HTTPS
   "Access-Control-Allow-Headers": "Origin,Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token,locale",
  "Access-Control-Allow-Methods": "POST, OPTIONS"
 },