使用C#如何使用HttpClient发送JSON数据？

Question

我不知道如何使用HttpClient POST JSON。我找到了一些解决方案，像这样，但是我必须使用HttpClient，因为它是异步的，并且必须添加一个标头。

以下是我的代码。有什么想法如何修复它？

List<Order> list = new List<Order> { new Order() { Name = "CreatedTime", OrderBy = 1 } };

Queues items = new Queues { Orders = list };

var values = new Dictionary<string, string> { { "Orders", JsonConvert.SerializeObject(list) } };

var content = new FormUrlEncodedContent(values);

//HttpContent cc = new StringContent(JsonConvert.SerializeObject(items));

_msg = await _client.PostAsync(input, content);

//_msg = await _client.PostAsync(input, cc);

var response = await _msg.Content.ReadAsStringAsync();

- Louis

Answer 1

你可以使用方法PostAsJsonAsync，该方法可以在扩展程序集中找到：

System.Net.Http.Formatting.dll

例子

public static async Task SendJsonDemo(object content)
{
    using(var client = new HttpClient())
    {
        var response = await client.PostAsJsonAsync("https://example.com", content);
    }
}

如果您想要向请求中添加自定义标头，请将其添加到DefaultRequestHeaders中：

client.DefaultRequestHeaders.Add("mycustom", "header1");

- Peter Mols

Answer 2

您可以发送任何类型的请求，例如

public static async Task<HttpResponseMessage> SendRequest(HttpMethod method, string endPoint, string accessToken,  dynamic content = null)
        {
            HttpResponseMessage response = null;
            using (var client = new HttpClient())
            {
                using (var request = new HttpRequestMessage(method, endPoint))
                {
                    request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
                    if (content != null)
                    {
                        string c;
                        if (content is string)
                            c = content;
                        else
                            c = JsonConvert.SerializeObject(content);
                        request.Content = new StringContent(c, Encoding.UTF8, "application/json");
                    }

                    response = await client.SendAsync(request).ConfigureAwait(false);
                }
            }
            return response;

        }

- Md. Abdul Alim

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我记得读过一篇文章，几乎可以确定不应该为每个调用实例化一个HttpClient。 - mwardm