Asp.Net 核心 HttpClient 收到响应 411 长度要求错误

Question

我正在尝试使用 C# HttpClient 创建一个将一些数据发布到 API 端点的服务。代码如下

public class HttpClientService : IHttpClientService
{
    static HttpClient client = new HttpClient();

    public HttpClientService()
    {
        client.BaseAddress = new Uri("http://xx.xx.xx.xx/");
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    }

    public async Task<Uri> MakeLogEntry(CnsLog log)
    {
        HttpResponseMessage response = await client.PostAsJsonAsync("api/logs", log);
        return response.Headers.Location;
    }

}

问题是终点returns错误411 Length Required。我发现这是因为我的请求没有 content-length header 集，我在使用 Fiddler 检查请求时发现这是真的。

我尝试在客户端的构造函数中设置内容长度 header，但此后代码无法编译。我被困住了，将不胜感激任何帮助。谢谢

Answer 1

或者您可以使用 HttpWebRequest。

byte[] postBytes = Encoding.ASCII.GetBytes(log);
request.ContentLength = postBytes.Length;

HttpWebRequest 示例如下：

ASCIIEncoding encoder = new ASCIIEncoding();
byte[] data = encoder.GetBytes(serializedObject); // a json object, or xml, whatever...

HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = data.Length;
request.Expect = "application/json";

request.GetRequestStream().Write(data, 0, data.Length);

HttpWebResponse response = request.GetResponse() as HttpWebResponse;

Answer 2

您不想在客户端上设置 Content-Length header，尤其是因为它是静态实例。您想根据个人要求进行设置。

PostAsJsonAsync 是一个很好的快捷方式，它从 poco 构建 HttpContent，从该内容构建 HttpRequestMessage，然后发送 POST 请求。很方便，但是所有这些抽象都不会给您设置 request-level header 的机会。因此，您需要为 build/send 请求做更多的工作：

var json = JsonConvert.SerializeObject(log);
var content = new StringContent(json, Encoding.UTF8, "application/json");
content.Headers.ContentLength = json.Length;
var response = await client.PostAsync("api/logs", content);

Asp.Net 核心 HttpClient 收到响应 411 长度要求错误

Asp.Net core HttpClient gets response 411 length required error

c#

asp.net

dotnet-httpclient