C#：带有 POST 参数的 HttpClient

Question

我使用以下代码向服务器发送 POST 请求：

string url = "http://myserver/method?param1=1&param2=2"    
HttpClientHandler handler = new HttpClientHandler();
HttpClient httpClient = new HttpClient(handler);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, url);
HttpResponseMessage response = await httpClient.SendAsync(request);

我无权访问要调试的服务器，但我想知道，这个请求是作为 POST 还是 GET 发送的？

如果是 GET，我如何更改代码以将 param1 和 param2 作为 POST 数据（不在 URL 中）发送？

Answer 1

更简洁的替代方法是使用Dictionary 来处理参数。毕竟它们是键值对。

private static readonly HttpClient httpclient;

static MyClassName()
{
    // HttpClient is intended to be instantiated once and re-used throughout the life of an application. 
    // Instantiating an HttpClient class for every request will exhaust the number of sockets available under heavy loads. 
    // This will result in SocketException errors.
    // https://docs.microsoft.com/en-us/dotnet/api/system.net.http.httpclient?view=netframework-4.7.1
    httpclient = new HttpClient();    
} 

var url = "http://myserver/method";
var parameters = new Dictionary<string, string> { { "param1", "1" }, { "param2", "2" } };
var encodedContent = new FormUrlEncodedContent (parameters);

var response = await httpclient.PostAsync (url, encodedContent).ConfigureAwait (false);
if (response.StatusCode == HttpStatusCode.OK) {
    // Do something with response. Example get content:
    // var responseContent = await response.Content.ReadAsStringAsync ().ConfigureAwait (false);
}

另外别忘了Dispose()httpclient，如果你不使用关键字using

正如Microsoft docs 中 HttpClient 类的备注部分所述，HttpClient 应该被实例化一次并重复使用。

编辑：

您可能想查看response.EnsureSuccessStatusCode(); 而不是if (response.StatusCode == HttpStatusCode.OK)。

你可能想保留你的 httpclient 而不要Dispose() 它。见：Do HttpClient and HttpClientHandler have to be disposed?

编辑：

不用担心在 .NET Core 中使用 .ConfigureAwait(false)。更多详情请查看https://blog.stephencleary.com/2017/03/aspnetcore-synchronization-context.html

Answer 2

正如 Ben 所说，您正在发布您的请求（代码中指定了 HttpMethod.Post）

url 中包含的查询字符串（get）参数可能不会做任何事情。

试试这个：

string url = "http://myserver/method";    
string content = "param1=1&param2=2";
HttpClientHandler handler = new HttpClientHandler();
HttpClient httpClient = new HttpClient(handler);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, url);
HttpResponseMessage response = await httpClient.SendAsync(request,content);

HTH，

bovako