Flutter HTTP Post 返回 415

Question

我在使用 http dart 库的颤振应用程序上使用 Method.Post 时遇到问题。似乎当我尝试从我的 WebAPI 发布数据时，它给了我一个StatusCode 415。请参阅下面的代码：

代码登录：

Future<User> login(User user) async {
print(URLRequest.URL_LOGIN);
return await _netUtil.post(Uri.encodeFull(URLRequest.URL_LOGIN), body: {
  'username': user.username,
  'password': user.password
}, headers: {
  "Accept": "application/json",
}).then((dynamic res) {
  print(res.toString());
});
}

代码 NetworkUtils：

Future<dynamic> post(String url, {Map headers, body, encoding}) async {
return await http
    .post(url, body: body, headers: headers, encoding: encoding)
    .then((http.Response response) {
  final String res = response.body;
  final int statusCode = response.statusCode;

  if (statusCode < 200 || statusCode > 400 || json == null) {
    throw new Exception('Error while fetching data.');
  }

  return _decoder.convert(res);
});
}

有人知道我的代码发生了什么吗？

Answer 1

尝试添加这个新标题：

headers: {
  "Accept": "application/json",
  "content-type":"application/json"
}

更新

好的，现在你需要发送 json 数据，像这样：

        import 'dart:convert';


         var body = jsonEncode( {
          'username': user.username,
          'password': user.password
        });


        return await _netUtil.post(Uri.encodeFull(URLRequest.URL_LOGIN), body: body, headers: {
          "Accept": "application/json",
          "content-type": "application/json"
        }).then((dynamic res) {
          print(res.toString());
        });
        }

Answer 2

@阿尔文奎松

我遇到了和你一样的错误并修复它，请参见下文。

[错误]

StateError（错误状态：无法设置内容类型为“application/json”的请求的正文字段。）

[原因]

当你使用Flutter插件'http.dart'方法'http.post()'时，你应该详细阅读下面的文档（注意黑色字体）：

Sends an HTTP POST request with the given headers and body to the given URL.
[body] sets the body of the request. It can be a [String], a [List<int>] or
a [Map<String, String>]. If it's a String, it's encoded using [encoding] and
used as the body of the request. The content-type of the request will
default to "text/plain".

If [body] is a List, it's used as a list of bytes for the body of the
request.

如果 [body] 是 Map，则使用 [encoding] 将其编码为表单字段。请求的内容类型将设置为"application/x-www-form-urlencoded"；这不能被覆盖。

[encoding] defaults to [utf8].

For more fine-grained control over the request, use [Request] or
[StreamedRequest] instead.
Future<Response> post(Uri url,
{Map<String, String>? headers, Object? body, Encoding? encoding}) =>
_withClient((client) =>
    client.post(url, headers: headers, body: body, encoding: encoding));

[解决方案]

所以只需将您的正文编码为字符串，然后您可以将标头“内容类型”设置为“应用程序/json”。 看到@diegoveloper 的代码回答了！