C# HttpClient 流式响应

有些时候需要边请求边显示响应内容：

用httpClient.SendAsync(httpreq, HttpCompletionOption.ResponseHeadersRead);

 private async void TestHttp()
        {

            DateTime d = DateTime.Now;
            HttpClient httpClient = new HttpClient();
            httpClient.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36 Edg/114.0.1823.58");
            httpClient.DefaultRequestHeaders.Add("Origin", "https://xxxx.com");
            httpClient.DefaultRequestHeaders.Add("Referer", "https://xxxxx.com/");
            StringContent jsonContent = new StringContent(
                JsonConvert.SerializeObject(new
                {
                    data= "你们的发货地是哪里？",
                    userId = "1211334",
                    title = "test",
                    usesyy = false
                }),
             Encoding.UTF8,
             "application/json");
            var httpreq = new HttpRequestMessage(HttpMethod.Post, "https://xxxxxx") { Content = jsonContent };
            var response = await httpClient.SendAsync(httpreq, HttpCompletionOption.ResponseHeadersRead);
            //var response = await httpClient.PostAsync("https://api.xxxxx", jsonContent);

            // 确保请求成功
            //response.EnsureSuccessStatusCode();
            string allStr = "";
            // 读取响应内容的异步流
            using (var responseStream = await response.Content.ReadAsStreamAsync())
            {
                Debug.Print("============start response use minseconds=" + (DateTime.Now - d).TotalMilliseconds + "  =================\r\n");
                // 逐块读取并处理响应内容
                var buffer = new byte[102];
                int bytesRead;
                while ((bytesRead = await responseStream.ReadAsync(buffer, 0, buffer.Length)) > 0)
                {
                    // 处理响应内容
                    string content = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead);
                    allStr += content;
                    Debug.Print("---------------" + content + "\r\n");
                }
            }
            var useTime = (DateTime.Now - d).TotalMilliseconds;
            var t2 = (DateTime.Now - DateTime.Now.AddMilliseconds(-100)).TotalMilliseconds;
            TestHttp();
        }