今天研究了一天C#如何添加cookie到httpcient里面，从而发请求时，能把cookie作为头部发出，最后发现根本加不进去。Httpclient的cookie是来自上一个请求的响应，httpclient会自动把上一个请求的响应里面的cookie保存起来，所以当发送几个有关联的request，就必须要用同一个Httpclient示例：//第一个请求            HttpClient client = new HttpClient();            // 为JSON格式添加一个Accept报头            //client.DefaultRequestHeaders.Accept.Add(            //    new MediaTypeWithQualityHeaderValue("application/json"));            string strDecodeBody = HttpUtility.UrlEncode(strBody);            HttpContent content = new StringContent(strDecodeBody);            content.Headers.ContentType = new MediaTypeHeaderValue("application/json");            client.DefaultRequestHeaders.Add("user-agent", "Mozilla/5.0");            client.DefaultRequestHeaders.Add("Authentication", "123");            HttpResponseMessage response = null;            response = client.PostAsync(strIP, content).Result;            if (response != null)            {                if (expectCode == HttpStatusCode.OK)                {                    var resultValue = response.Content.ReadAsStringAsync().Result;                    string strResponse = HttpUtility.UrlDecode(resultValue.ToString());                    string[] strCookies = (string[])response.Headers.GetValues("Set-Cookie");                    if(strCookies.Length>0)                    {                        strCookie = strCookies[0].Substring(0, strCookies[0].IndexOf(';'));                    }                }            } //第二个请求，在这个请求里，没有设置cookie，由于跟第一个请求使用相同httpclient，所以cookie会自动放入请求头部发给服务器            string strEncodeBody = HttpUtility.UrlEncode(strBody);            HttpContent content = new StringContent(strEncodeBody);            content.Headers.ContentType = new MediaTypeHeaderValue("application/json");            HttpResponseMessage response = null;            response = client.PostAsync(strIP, content).Result;            if (response != null)            {                if (expectCode == HttpStatusCode.OK)                {                    var resultValue = response.Content.ReadAsStringAsync().Result;                    string strResponse = HttpUtility.UrlDecode(resultValue.ToString());                    return strResponse;                }            }顶