使用MultipartFormDataContent生成错误的Content-Type标头

我有以下代码：

private static string boundary = "----CustomBoundary" + DateTime.Now.Ticks.ToString("x"); private static async Task PostTest() { string servResp = ""; using (var content = new MultipartFormDataContent(boundary)) { content.Add(new StringContent("105212"), "case-id"); content.Add(new StringContent("1/14/2014"), "dateFrom"); content.Add(new StringContent("1/15/2014"), "dateTo"); HttpClientHandler handler = new HttpClientHandler(); cookieContainer = new CookieContainer(); handler.CookieContainer = cookieContainer; HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "http://somewebsite.com/form"); request.Headers.ExpectContinue = false; request.Content = content; httpClient = new HttpClient(handler); HttpResponseMessage response = await httpClient.SendAsync(request); response.EnsureSuccessStatusCode(); servResp = await response.Content.ReadAsStringAsync(); } return servResp; } 

当我运行它时，我在Fiddler中看到了Content-Type标头：

 Content-Type: multipart/form-data; boundary="----CustomBoundary8d0f01e6b3b5daf" 

由于边界值在引号中，服务器会忽略请求正文。 如果我删除引号并在Fiddler Composer中运行请求，则正在正确处理请求。

我尝试添加内容标题：

 //request.Content.Headers.Add("Content-Type", "multipart/form-data; boundary=" + boundary); //request.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("multipart/form-data; boundary=" + boundary); 

…但它不起作用，错误消息是：“无法添加值，因为标题’Content-Type’不支持多个值。” 和“格式值’multipart / form-data，boundary = —- CustomBoundary8d0f024297b32d5’无效。”，相应地。

如何将正确的Content-Type标头添加到请求中，以便边界值不会用引号括起来？

 Content-Type: multipart/form-data; boundary=----CustomBoundary8d0f01e6b3b5daf 

Answer 1

通过从MultipartFormDataContent中删除标头并重新添加它而不进行validation来解决此问题：

 content.Headers.Remove("Content-Type"); content.Headers.TryAddWithoutValidation("Content-Type", "multipart/form-data; boundary=" + boundary);