解析C#网络编程中的Http请求

本篇分享简单介绍C#中的Http请求,前几天帮朋友的项目封装ApiHelper,我粗糙的结果就如下，想想我真的是差的太远了。还有一位架构师也在封装这个Helper , 所以最后的结果当然是使用大牛的封装，这篇分享后，准备学习下他的封装，配置，错误处理机制等思想。不过这次也使我对C#网络编程了解的更多，算是一次学习经历吧。真心喜欢和老司机合作，下一阶段将会持续跟这位朋友学习项目底层的封装，和他谦虚的态度，有这样的机会也是幸运的。

你可以将其封装成自己的HttpHelper，经朋友建议，统一Http请求的入参和出参。在HttpClient方面也参考了dudu的关于httpclient预热的文章。C#中HttpClient使用注意：预热与长连接。

为了做到统一入参和出参，定义了Req<T>泛型类和Resp<T>泛型类。你可以根据自己的需要进行拓展。

public class Req<T>
    {
        /// <summary>
        /// 传入数据
        /// </summary>
        public T Input { get; set; }
        /// <summary>
        /// 请求地址
        /// </summary>
        public string Url { get; set; }
    }

public class Resp<T>
    {
        /// <summary>
        /// 错误消息
        /// </summary>
        public string ErrorMsg { get; set; }
        /// <summary>
        /// 状态码
        /// </summary>
        public int StatusCode { get; set; }
        /// <summary>
        /// 返回数据
        /// </summary>
        public T RespData { get; set; }
    }

虽然保持了httpClient对象复用，但需要注意的是，在设置了httpClient，并且发生了一次请求之后，不能再对其属性进行重新设置。这也正是我又定义了一个fileClient的理由。

  #region HttpClient版本
         private static readonly string _baseAddress = ConfigurationManager.AppSettings["api-server"];//配置BaseUrl eg.http://localhost:1234
        private static readonly HttpClient _httpClient;
       private static readonly HttpClient _fileClient;
         static ApiHelper()
         {
              #region 初始化和预热 httpClient
             _httpClient = new HttpClient();
            _httpClient.BaseAddress = new Uri(_baseAddress);
             _httpClient.Timeout = TimeSpan.FromMilliseconds(2000);
            _httpClient.DefaultRequestHeaders.Add("Accept", "application/json");//application/xml  想Accept的数据格式
            _httpClient.SendAsync(new HttpRequestMessage
            {
                Method = new HttpMethod("HEAD"),
                 RequestUri = new Uri(_baseAddress + "/api/test/HttpClientHot")
             })
             .Result.EnsureSuccessStatusCode();
             #endregion
            #region 初始化和预热 fileClient
            _fileClient = new HttpClient();
             _fileClient.BaseAddress = new Uri(_baseAddress + "/api/test/HttpClientHot");
            _fileClient.MaxResponseContentBufferSize = 256000;
            #endregion
        }
         /// <summary>
         /// http Get请求
        /// </summary>
         /// <typeparam name="T">入参类型</typeparam>
        /// <typeparam name="TResult">出参类型</typeparam>
        /// <param name="req">入参对象</param>
        /// <returns></returns>
         public static async Task<Resp<TResult>> GetAsync<T, TResult>(Req<T> req)
        {
            try
                var result =await _httpClient.GetAsync(req.Url).Result.Content.ReadAsStringAsync();
                return new Resp<TResult>() { Data = JsonHelper.JsonDeserialize<TResult>(result) };
             }
            catch(Exception ex)
              }
                 return new Resp<TResult>() { Data = JsonHelper.JsonDeserialize<TResult>("") };
       }
          /// <summary>
          ///  http Post请求
          /// </summary>
          /// <typeparam name="T">入参类型</typeparam>
          /// <typeparam name="TResult">出参类型</typeparam>
          /// <param name="req">入参对象</param>
          /// <returns></returns>
          public static async Task<Resp<TResult>> PostAsJsonAsync<T, TResult>(Req<T> req)
              var result = await _httpClient.PostAsJsonAsync(req.Url, req.Input).Result.Content.ReadAsStringAsync();
              return new Resp<TResult>() { Data = JsonHelper.JsonDeserialize<TResult>(result) };
          }
         /// 上传文件
         /// <typeparam name="T"></typeparam>
         /// <typeparam name="TResult"></typeparam>
         /// <param name="req"></param>
         /// <param name="filePath"></param>
        public static async Task<Resp<TResult>> SendFile<T, TResult>(Req<T> req, string filePath)//D:\\white.webp
             //_fileClient.DefaultRequestHeaders.Add("user-agent", "User-Agent    Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; Touch; MALNJS; rv:11.0) like Gecko");//设置请求头
            // 读文件流
             FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
              HttpContent fileContent = new StreamContent(fs);//为文件流提供的HTTP容器
             fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");//设置媒体类型
            MultipartFormDataContent mulContent = new MultipartFormDataContent("----");//创建用于可传递文件的容器
              string fileName = filePath.Substring(filePath.LastIndexOf("/") + 1);
             mulContent.Add(fileContent, "form", fileName);//第二个参数是表单名，第三个是文件名。
              HttpResponseMessage response = await _fileClient.PostAsync(req.Url, mulContent);
             response.EnsureSuccessStatusCode();
             string result = await response.Content.ReadAsStringAsync();
             return new Resp<TResult>() { Data = JsonHelper.JsonDeserialize<TResult>(result) };
         }
         /// 下载
        /// <param name="url"></param>
         /// <returns></returns>
        public static async Task<Resp<byte[]>> HttpDownloadData<T>(Req<T> req)
             var byteres = await _fileClient.GetByteArrayAsync(req.Url);
             return new Resp<byte[]>() { Data = byteres };
        #endregion
 }

另外分享下HttpWebRequest来实现的请求。HttpWebRequest需要你自行设置很多内容，当然这也证明其内容丰富。下面代码包含了post,get，以及上传。

/// <summary>
        /// Post Http请求
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="postData">传输数据</param>
        /// <param name="timeout">超时时间</param>
        /// <param name="contentType">媒体格式</param>
        /// <param name="encode">编码</param>
        /// <returns>泛型集合</returns>
        public static List<T> PostAndRespList<T>(string url, string postData, int timeout = 5000, string contentType = "application/json;", string encode = "UTF-8")
        {
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode) && !string.IsNullOrEmpty(contentType) && postData != null)
            {
                // webRequest.Headers.Add("Authorization", "Bearer " + "SportApiAuthData");
                HttpWebResponse webResponse = null;
                Stream responseStream = null;
                Stream requestStream = null;
                StreamReader streamReader = null;
                try
                {
                    string respstr = GetStreamReader(url, responseStream, requestStream, streamReader, webResponse, timeout, encode, postData, contentType);
                    return JsonHelper.JsonDeserialize<List<T>>(respstr);
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    if (responseStream != null) responseStream.Dispose();
                    if (webResponse != null) webResponse.Dispose();
                    if (requestStream != null) requestStream.Dispose();
                    if (streamReader != null) streamReader.Dispose();
                }
            }
            return null;
        }
        /// <summary>
        /// Post Http请求
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="postData">传输数据</param>
        /// <param name="timeout">超时时间</param>
        /// <param name="contentType">媒体格式</param>
        /// <param name="encode">编码</param>
        /// <returns>泛型集合</returns>
        public static T PostAndRespSignle<T>(string url, int timeout = 5000, string postData = "", string contentType = "application/json;", string encode = "UTF-8")
        {
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode) && !string.IsNullOrEmpty(contentType) && postData != null)
            {
                // webRequest.Headers.Add("Authorization", "Bearer " + "SportApiAuthData");
                HttpWebResponse webResponse = null;
                Stream responseStream = null;
                Stream requestStream = null;
                StreamReader streamReader = null;
                try
                {
                    string respstr = GetStreamReader(url, responseStream, requestStream, streamReader, webResponse, timeout, encode, postData, contentType);
                    return JsonHelper.JsonDeserialize<T>(respstr);
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    if (responseStream != null) responseStream.Dispose();
                    if (webResponse != null) webResponse.Dispose();
                    if (requestStream != null) requestStream.Dispose();
                    if (streamReader != null) streamReader.Dispose();
                }
            }
            return default(T);
        }
        /// <summary>
        /// Post Http请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="postData"></param>
        /// <param name="timeout"></param>
        /// <param name="contentType"></param>
        /// <param name="encode"></param>
        /// <returns>响应流字符串</returns>
        public static string PostAndRespStr(string url, int timeout = 5000, string postData = "", string contentType = "application/json;", string encode = "UTF-8")
        {
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode) && !string.IsNullOrEmpty(contentType) && postData != null)
            {
                HttpWebResponse webResponse = null;
                Stream responseStream = null;
                Stream requestStream = null;
                StreamReader streamReader = null;
                try
                {
                    return GetStreamReader(url, responseStream, requestStream, streamReader, webResponse, timeout, encode, postData, contentType);
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    if (responseStream != null) responseStream.Dispose();
                    if (webResponse != null) webResponse.Dispose();
                    if (requestStream != null) requestStream.Dispose();
                    if (streamReader != null) streamReader.Dispose();
                }
            }
            return null;
        }
        private static string GetStreamReader(string url, Stream responseStream, Stream requestStream, StreamReader streamReader, WebResponse webResponse, int timeout, string encode, string postData, string contentType)
        {
            byte[] data = Encoding.GetEncoding(encode).GetBytes(postData);
            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);
            SetAuth(webRequest);
            webRequest.Method = "POST";
            webRequest.ContentType = contentType + ";" + encode;
            webRequest.ContentLength = data.Length;
            webRequest.Timeout = timeout;
            requestStream = webRequest.GetRequestStream();
            requestStream.Write(data, 0, data.Length);
            webResponse = (HttpWebResponse)webRequest.GetResponse();
            responseStream = webResponse.GetResponseStream();
            if (responseStream == null) { return ""; }
            streamReader = new StreamReader(responseStream, Encoding.GetEncoding(encode));
            return streamReader.ReadToEnd();
        }
        /// <summary>
        /// Post文件流给指定Url
        /// </summary>
        /// <param name="url">url</param>
        /// <param name="filePath">文件路径</param>
        /// <returns>响应流字符串</returns>
        public static string PostFile(string url, string filePath, string contentType = "application/octet-stream", string encode = "UTF-8")
        {
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode) && !string.IsNullOrEmpty(contentType) && !string.IsNullOrEmpty(filePath))
            {
                Stream requestStream = null;
                Stream responseStream = null;
                StreamReader streamReader = null;
                FileStream fileStream = null;
                try
                {
                    // 设置参数
                    HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
                    SetAuth(webRequest);
                    webRequest.AllowAutoRedirect = true;
                    webRequest.Method = "POST";
                    string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线
                    webRequest.ContentType = "multipart/form-data;charset=" + encode + ";boundary=" + boundary;
                    byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");//消息开始
                    byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");//消息结尾
                    var fileName = filePath.Substring(filePath.LastIndexOf("/") + 1);
                    //请求头部信息
                    string postHeader = string.Format("Content-Disposition:form-data;name=\"media\";filename=\"{0}\"\r\nContent-Type:{1}\r\n\r\n", fileName, contentType);
                    byte[] postHeaderBytes = Encoding.UTF8.GetBytes(postHeader);
                    fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
                    byte[] fileByteArr = new byte[fileStream.Length];
                    fileStream.Read(fileByteArr, 0, fileByteArr.Length);
                    fileStream.Close();
                    requestStream = webRequest.GetRequestStream();
                    requestStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                    requestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
                    requestStream.Write(fileByteArr, 0, fileByteArr.Length);
                    requestStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);
                    requestStream.Close();
                    responseStream = webRequest.GetResponse().GetResponseStream();//发送请求，得到响应流
                    if (responseStream == null) return string.Empty;
                    streamReader = new StreamReader(responseStream, Encoding.UTF8);
                    return streamReader.ReadToEnd();
                }
                catch (Exception ex)
                {
                }
                finally
                {
                }
            }
            return null;
        }
        /// <summary>
        /// Get http请求
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="timeout">超时时间</param>
        /// <param name="encode">编码</param>
        /// <returns>返回单个实体</returns>
        public static T GetSingle<T>(string url, int timeout = 5000, string encode = "UTF-8")
        {
            //HttpWebRequest对象
            //HttpClient->dudu 调用预热处理
            //Stream—>Model
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode))
            {
                Stream responseStream = null;
                StreamReader streamReader = null;
                WebResponse webResponse = null;
                try
                {
                    string respStr = GetRespStr(url, responseStream, streamReader, webResponse, timeout, encode);
                    return JsonHelper.JsonDeserialize<T>(respStr);
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    if (responseStream != null) responseStream.Dispose();
                    if (streamReader != null) streamReader.Dispose();
                    if (webResponse != null) webResponse.Dispose();
                }
            }
            return default(T);
        }
        /// <summary>
        ///  Get http请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="timeout"></param>
        /// <param name="encode"></param>
        /// <returns>响应流字符串</returns>
        public static string GetResponseString(string url, int timeout = 5000, string encode = "UTF-8")
        {
            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(encode))
            {
                Stream responseStream = null;
                StreamReader streamReader = null;
                WebResponse webResponse = null;
                try
                {
                    return GetRespStr(url, responseStream, streamReader, webResponse, timeout, encode);
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    if (responseStream != null) responseStream.Dispose();
                    if (streamReader != null) streamReader.Dispose();
                    if (webResponse != null) webResponse.Dispose();
                }
            }
            return null;
        }
        private static string GetRespStr(string url, Stream responseStream, StreamReader streamReader, WebResponse webResponse, int timeout, string encode)
        {
            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);
            webRequest.Method = "GET";
            webRequest.Timeout = timeout;
            webResponse = webRequest.GetResponse();
            responseStream = webResponse.GetResponseStream();
            if (responseStream == null) { return ""; }
            streamReader = new StreamReader(responseStream, Encoding.GetEncoding(encode));
            return streamReader.ReadToEnd();
         }

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