HttpClient请求的自定义标头

如何在HttpClient请求中添加自定义标头？我正在使用PostAsJsonAsync发布JSON的方法。我需要添加的自定义标头是

"X-Version: 1"

到目前为止，这是我所做的：

using (var client = new HttpClient()) {
    client.BaseAddress = new Uri("https://api.clickatell.com/");
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "xxxxxxxxxxxxxxxxxxxx");
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    var response = client.PostAsJsonAsync("rest/message", svm).Result;
}

var request = new HttpRequestMessage {
    RequestUri = new Uri("[your request url string]"),
    Method = HttpMethod.Post,
    Headers = {
        { "X-Version", "1" } // HERE IS HOW TO ADD HEADERS,
        { HttpRequestHeader.Authorization.ToString(), "[your authorization token]" },
        { HttpRequestHeader.ContentType.ToString(), "multipart/mixed" },//use this content type if you want to send more than one content type
    },
    Content = new MultipartContent { // Just example of request sending multipart request
        new ObjectContent<[YOUR JSON OBJECT TYPE]>(
            new [YOUR JSON OBJECT TYPE INSTANCE](...){...}, 
            new JsonMediaTypeFormatter(), 
            "application/json"), // this will add 'Content-Type' header for the first part of request
        new ByteArrayContent([BINARY DATA]) {
            Headers = { // this will add headers for the second part of request
                { "Content-Type", "application/Executable" },
                { "Content-Disposition", "form-data; filename=\"test.pdf\"" },
            },
        },
    },
};

我找到了我问题的答案。

client.DefaultRequestHeaders.Add("X-Version","1");

那应该在您的请求中添加一个自定义标头

这是基于Anubis的答案（这是一种更好的方法，因为它不会为每个请求修改标头），但与原始问题中的代码等效：

using Newtonsoft.Json;
...

    var client = new HttpClient();
    var httpRequestMessage = new HttpRequestMessage
        {
            Method = HttpMethod.Post,
            RequestUri = new Uri("https://api.clickatell.com/rest/message"),
            Headers = { 
                { HttpRequestHeader.Authorization.ToString(), "Bearer xxxxxxxxxxxxxxxxxxxx" },
                { HttpRequestHeader.Accept.ToString(), "application/json" },
                { "X-Version", "1" }
            },
            Content = new StringContent(JsonConvert.SerializeObject(svm))
        };

    var response = client.SendAsync(httpRequestMessage).Result;

该类中有一个Headers属性HttpRequestMessage。您可以在此处添加自定义标头，该标头将随每个HTTP请求一起发送。的DefaultRequestHeaders在HttpClient类，另一方面，设置为与每个请求一起发送报头使用该客户对象，因此得名发送默认请求头。

希望这使事情变得更清楚，至少对于将来看到这个答案的人来说。