标题（内容类型：应用程序/JSON）和请求有效负载/数据。

PATCH http://localhost:5000/users/61b6356454f499270755aee9
content-type: application/json

{
  "first_name": "John"
}

你必须在你的身体前面放一个空行

无效

POST http://localhost:3000/api/report/expense/create HTTP/1.1
Content-Type: application/json
{
    "source": "Business",
    "amount": 200
}

有效

POST http://localhost:3000/api/report/expense/create HTTP/1.1
Content-Type: application/json

{
    "source": "Business",
    "amount": 200
}

您将授权密钥放在标头参数中
{“授权：您的API密钥”}
从here查找更多信息

您可以改用http.Client（），如下所示：

class API_Manager {
      Future<Model> getData() async {
        var client = http.Client();
        var Model;
        String url =
            'https://examplelink.com';
        String basicAuth = 'Basic your_auth_key_here';
        try {
          var response = await client.get(url,
              headers: <String, String>{'authorization': basicAuth});
          print(response.statusCode);
          developer.log(response.body); //to get your json data
          if (response.statusCode == 200) {
            var jsonString = response.body;
            var jsonMap = json.decode(jsonString);
            Model = MyModel.fromJson(jsonMap);
          }
        } catch (Exception) {
          return Model;
        }
        return Model;
      }
    }

我找到了答案，我们必须在标题中手动写这部分：）