c# .net core 下的網絡請求

本文章是在VS2017的環境下，.net core 1.1版本以上。

在這期間，因爲.net core 並不基於IIS，咱們的過去的網絡請求代碼在.net core框架下，有可能會出現不兼容，報錯的現象。這裏大體介紹下在.net core 下如何進行http請求，主要仍然是GET和POST方法，有錯誤的地方，歡迎指正！

先來講POST,POST我實現了三種方法，前兩種基於的原理是徹底一致的，後面的有些小小的差別，但他們的本質都是http請求，本質上是無區別的，只是實現方法有所不一樣。

廢話很少說，上代碼：

POST異步方法：

 /// <summary>
        /// 異步請求post（鍵值對形式,可等待的）
        /// </summary>
        /// <param name="uri">網絡基址("http://localhost:59315")</param>
        /// <param name="url">網絡的地址("/api/UMeng")</param>
        /// <param name="formData">鍵值對List<KeyValuePair<string, string>> formData = new List<KeyValuePair<string, string>>();formData.Add(new KeyValuePair<string, string>("userid", "29122"));formData.Add(new KeyValuePair<string, string>("umengids", "29122"));</param>
        /// <param name="charset">編碼格式</param>
        /// <param name="mediaType">頭媒體類型</param>
        /// <returns></returns>
        public async  Task<string> HttpPostAsync(string uri, string url, List<KeyValuePair<string, string>> formData = null, string charset = "UTF-8", string mediaType = "application/x-www-form-urlencoded")
        {
           
            string tokenUri = url;
            var client = new HttpClient();
            client.BaseAddress = new Uri(uri);
            HttpContent content = new FormUrlEncodedContent(formData);
            content.Headers.ContentType = new MediaTypeHeaderValue(mediaType);
            content.Headers.ContentType.CharSet = charset;
            for (int i = 0; i < formData.Count; i++)
            {
                content.Headers.Add(formData[i].Key, formData[i].Value);
            }
            
            HttpResponseMessage resp = await client.PostAsync(tokenUri, content);
            resp.EnsureSuccessStatusCode();
            string token = await resp.Content.ReadAsStringAsync();
            return token;
        }

POST同步方法：

/// <summary>
        /// 同步請求post（鍵值對形式）
        /// </summary>
        /// <param name="uri">網絡基址("http://localhost:59315")</param>
        /// <param name="url">網絡的地址("/api/UMeng")</param>
        /// <param name="formData">鍵值對List<KeyValuePair<string, string>> formData = new List<KeyValuePair<string, string>>();formData.Add(new KeyValuePair<string, string>("userid", "29122"));formData.Add(new KeyValuePair<string, string>("umengids", "29122"));</param>
        /// <param name="charset">編碼格式</param>
        /// <param name="mediaType">頭媒體類型</param>
        /// <returns></returns>
        public string HttpPost(string uri, string url, List<KeyValuePair<string, string>> formData = null, string charset = "UTF-8", string mediaType = "application/x-www-form-urlencoded")
        {            
            string tokenUri = url;
            var client = new HttpClient();
            client.BaseAddress = new Uri(uri);
            HttpContent content = new FormUrlEncodedContent(formData);
            content.Headers.ContentType = new MediaTypeHeaderValue(mediaType);
            content.Headers.ContentType.CharSet = charset;
            for (int i = 0; i < formData.Count; i++)
            {
                content.Headers.Add(formData[i].Key, formData[i].Value);
            }

            var res = client.PostAsync(tokenUri, content);
            res.Wait();
            HttpResponseMessage resp = res.Result;
            
            var res2 = resp.Content.ReadAsStringAsync();
            res2.Wait();

            string token = res2.Result;
            return token;
        }

遺憾的是，同步方法也是基於異步實現的，我的認爲這樣作會加大系統開銷。若是各位有其餘的高效實現，請不吝賜教！

接下來是經過流的方式進行POST：

public string Post(string url, string data, Encoding encoding, int type)
        {
            try
            {
                HttpWebRequest req = WebRequest.CreateHttp(new Uri(url));
                if (type == 1)
                {
                    req.ContentType = "application/json;charset=utf-8";
                }
                else if (type == 2)
                {
                    req.ContentType = "application/xml;charset=utf-8";
                }
                else
                {
                    req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
                }

                req.Method = "POST";
                //req.Accept = "text/xml,text/javascript";
                req.ContinueTimeout = 60000;

                byte[] postData = encoding.GetBytes(data);
                Stream reqStream = req.GetRequestStreamAsync().Result;
                reqStream.Write(postData, 0, postData.Length);
                reqStream.Dispose();

                var rsp = (HttpWebResponse)req.GetResponseAsync().Result;
                var result = GetResponseAsString(rsp, encoding);
                return result;
                
            }
            catch (Exception ex)
            {
                throw;
            }
        }

 private string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            Stream stream = null;
            StreamReader reader = null;

            try
            {
                // 以字符流的方式讀取HTTP響應
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);
                return reader.ReadToEnd();
            }
            finally
            {
                // 釋放資源
                if (reader != null) reader.Dispose();
                if (stream != null) stream.Dispose();
                if (rsp != null) rsp.Dispose();
            }
        }

 

 

這種方式的POST仍是將數據寫入到流裏面，進行POST,之因此寫前兩個key-value的形式，是爲了符合java或者oc的風格，在c#書寫的webapi中，因爲接收形式是{=value}而不是{key=value}(由webapi的性質決定)，後續我會說如何在webapi中接收（key-value）的形式，適當避免.net後臺人員與android和ios的矛盾，從而達到社會主義民主社會的長治久安。

接下來是get，一樣同步異步都是由異步實現的，還請各位看官輕噴。

GET：

 /// <summary>
        /// 異步請求get(UTF-8)
        /// </summary>
        /// <param name="url">連接地址</param>       
        /// <param name="formData">寫在header中的內容</param>
        /// <returns></returns>
        public static async Task<string> HttpGetAsync(string url,  List<KeyValuePair<string, string>> formData = null)
        {
            HttpClient httpClient = new HttpClient();
            HttpContent content = new FormUrlEncodedContent(formData);
            if (formData != null)
            {
                content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
                content.Headers.ContentType.CharSet = "UTF-8";
                for (int i = 0; i < formData.Count; i++)
                {
                    content.Headers.Add(formData[i].Key, formData[i].Value);
                }
            }
            var request = new HttpRequestMessage()
            {
                RequestUri = new Uri(url),
                Method = HttpMethod.Get,
            };
            for (int i = 0; i < formData.Count; i++)
            {
                request.Headers.Add(formData[i].Key, formData[i].Value);
            }
            var resp = await httpClient.SendAsync(request);
            resp.EnsureSuccessStatusCode();
            string token = await resp.Content.ReadAsStringAsync();

            return token;
        }

 

 /// <summary>
        /// 同步get請求
        /// </summary>
        /// <param name="url">連接地址</param>       
        /// <param name="formData">寫在header中的鍵值對</param>
        /// <returns></returns>
        public  string HttpGet(string url, List<KeyValuePair<string, string>> formData = null)
        {
            HttpClient httpClient = new HttpClient();
            HttpContent content = new FormUrlEncodedContent(formData);
            if (formData != null)
            {
                content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
                content.Headers.ContentType.CharSet = "UTF-8";
                for (int i = 0; i < formData.Count; i++)
                {
                    content.Headers.Add(formData[i].Key, formData[i].Value);
                }
            }
            var request = new HttpRequestMessage()
            {
                RequestUri = new Uri(url),
                Method = HttpMethod.Get,
            };
            for (int i = 0; i < formData.Count; i++)
            {
                request.Headers.Add(formData[i].Key, formData[i].Value);
            }
            var res =  httpClient.SendAsync(request);
            res.Wait();
            var resp = res.Result;
            Task<string> temp = resp.Content.ReadAsStringAsync();
            temp.Wait();
            return temp.Result;
        }

以上就是這樣吧，還有，我是一個經不起批評的人，若是你批評我，我就罵你（玩笑）。請你們不吝賜教！感謝