從 HttpWebRequest 轉移到 HttpClient

Question

我想將一些遺留代碼從使用 HttpWebRequest 更新為使用 HttpClient，但我不太確定如何將字符串發送到我正在訪問的 REST API。

遺留代碼：

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.Method = "POST";
request.ContentType = "text/xml";
request.ContentLength = payload.Length;
if (credentials != null)
{
     request.Credentials = credentials;
}

// Send the request
Stream requestStream = request.GetRequestStream();
requestStream.Write(payload, 0, payload.Length);
requestStream.Close();

// Get the response
response = (HttpWebResponse)request.GetResponse();

我可以像處理 web 請求那樣使用 HttpClient.GetStreamAsync 方法並使用 stream 嗎？ 或者有沒有辦法對內容使用 SendAsync 然后得到響應？

Answer 1

你不需要訪問請求stream，你可以直接發送payload，但如果背后有原因，那么這也是可以的。

//Do not instantiate httpclient like that, use dependency injection instead
var httpClient = new HttpClient();
var httpRequest = new HttpRequestMessage();

//Set the request method (e.g. GET, POST, DELETE ..etc.)
httpRequest.Method = HttpMethod.Post;
//Set the headers of the request
httpRequest.Headers.Add("Content-Type", "text/xml");

//A memory stream which is a temporary buffer that holds the payload of the request
using (var memoryStream = new MemoryStream())
{
    //Write to the memory stream
    memoryStream.Write(payload, 0, payload.Length);

    //A stream content that represent the actual request stream
    using (var stream = new StreamContent(memoryStream))
    {
        httpRequest.Content = stream;

        //Send the request
        var response = await httpClient.SendAsync(httpRequest);


        //Ensure we got success response from the server
        response.EnsureSuccessStatusCode();
        //you can access the response like that
        //response.Content
    }
}

關於憑據，你需要知道這些是什么憑據？ 是基本授權嗎？

如果它是基本身份驗證，那么您可以（在HttpRequestMessage object 中設置請求 URI 時，您也可以在那里構建憑據。

var requestUri = new UriBuilder(yourEndPoint)
                        {
                            UserName = UsernameInCredentials,
                            Password = PasswordInCredentials,
                        }
                        .Uri;

然后您只需將其設置為請求 URI。 在此處閱讀有關為什么我們不應該像這樣實例化HttpClient的更多信息

Answer 2

using var handler = new HttpClientHandler { Credentials = ... };
using var client = new HttpClient(handler);

var content = new StringContent(payload, Encoding.UTF8, "text/xml");
var response = await client.PostAsync(uri, content);

我假設payload是一個string 。