C# Httpclient编程

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;
                }
            }