我试图设置一个HttpClient对象的Content-Type头作为我调用的API所要求的。
我试着像下面这样设置内容类型:
using (var httpClient = new HttpClient())
{
httpClient.BaseAddress = new Uri("http://example.com/");
httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
httpClient.DefaultRequestHeaders.Add("Content-Type", "application/json");
// ...
}
它允许我添加Accept头，但当我尝试添加Content-Type时，它会抛出以下异常:
误用头名称。确保请求头与一起使用 HttpRequestMessage，带有HttpResponseMessage的响应头，以及 内容头与HttpContent对象。
如何在HttpClient请求中设置内容类型报头?
当前回答
尝试使用TryAddWithoutValidation
var client = new HttpClient();
client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
其他回答
尝试使用HttpClientFactory
services.AddSingleton<WebRequestXXX>()
.AddHttpClient<WebRequestXXX>("ClientX", config =>
{
config.BaseAddress = new System.Uri("https://jsonplaceholder.typicode.com");
config.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
config.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
});
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
public class WebRequestXXXX
{
private readonly IHttpClientFactory _httpClientFactory;
public WebRequestXXXX(IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
}
public List<Posts> GetAllPosts()
{
using (var _client = _httpClientFactory.CreateClient("ClientX"))
{
var response = _client.GetAsync("/posts").Result;
if (response.IsSuccessStatusCode)
{
var itemString = response.Content.ReadAsStringAsync().Result;
var itemJson = System.Text.Json.JsonSerializer.Deserialize<List<Posts>>(itemString,
new System.Text.Json.JsonSerializerOptions
{
PropertyNameCaseInsensitive = true
});
return itemJson;
}
else
{
return new List<Posts>();
}
}
}
}
内容类型是内容的头，而不是请求的头，这就是失败的原因。Robert Levy建议的AddWithoutValidation可以工作，但是你也可以在创建请求内容本身时设置内容类型(注意，代码片段在两个地方添加了application/json - Accept和content - type头):
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://example.com/");
client.DefaultRequestHeaders
.Accept
.Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "relativeAddress");
request.Content = new StringContent("{\"name\":\"John Doe\",\"age\":33}",
Encoding.UTF8,
"application/json");//CONTENT-TYPE header
client.SendAsync(request)
.ContinueWith(responseTask =>
{
Console.WriteLine("Response: {0}", responseTask.Result);
});
一些关于。net Core的额外信息(在阅读了erdomke关于设置私有字段以在没有内容的请求上提供内容类型的文章后)…
在调试我的代码之后，我无法通过反射看到要设置的私有字段-所以我想我应该尝试重新创建这个问题。
我使用。net 4.6尝试了以下代码:
HttpRequestMessage httpRequest = new HttpRequestMessage(HttpMethod.Get, @"myUrl");
httpRequest.Content = new StringContent(string.Empty, Encoding.UTF8, "application/json");
HttpClient client = new HttpClient();
Task<HttpResponseMessage> response = client.SendAsync(httpRequest); //I know I should have used async/await here!
var result = response.Result;
正如预期的那样，我得到了一个聚合异常，其内容为“无法发送具有此动词类型的内容体”。
然而，如果我用。net Core(1.1)做同样的事情-我不会得到异常。我的服务器应用程序非常高兴地回答了我的请求，并选择了内容类型。
我对此感到惊喜，我希望它能帮助到一些人!
Api返回
"不支持的媒体类型"，"状态":415
添加ContentType到jsonstring做了魔法，这是我的脚本工作100%到今天为止
using (var client = new HttpClient())
{
var endpoint = "api/endpoint;
var userName = "xxxxxxxxxx";
var passwd = "xxxxxxxxxx";
var content = new StringContent(jsonString, Encoding.UTF8, "application/json");
var authToken = Encoding.ASCII.GetBytes($"{userName}:{passwd}");
client.BaseAddress = new Uri("https://example.com/");
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(authToken));
HttpResponseMessage response = await client.PostAsync(endpoint, content);
if (response.IsSuccessStatusCode)
{
// Get the URI of the created resource.
Uri returnUrl = response.Headers.Location;
Console.WriteLine(returnUrl);
}
string responseBody = await response.Content.ReadAsStringAsync();
return responseBody;
}
对于那些想要专门将Content-Type设置为Json的人，你可以使用扩展方法PostAsJsonAsync。
using System.Net.Http.Json; //this is needed for PostAsJsonAsync to work
//....
HttpClient client = new HttpClient();
HttpResponseMessage response = await
client.PostAsJsonAsync("http://example.com/" + "relativeAddress",
new
{
name = "John Doe",
age = 33
});
//Do what you need to do with your response
这样做的好处是代码更简洁，并且可以避免字符串化的json。更多详情请访问:https://learn.microsoft.com/en-us/previous-versions/aspnet/hh944339(v=vs.118)
