C# 通过 HttpWebRequest发送数据以及服务器通过Request请求获取数据

C# 通过 HttpWebRequest发送数据以及服务器通过Request请求获取数据, 后台请求的三种类型"application/x-www-form-urlencoded"和"multipart/form-data"以及"application/json"，对应的服务器端应该获取数据参数的方法

C#中HttpWebRequest的用法详解 可参考：

C#中HttpWebRequest的用法详解
C# HttpWebRequest详解
C# 服务器通过Request获取参数 可参考：
C# WebService 接口 通过Request请求获取json参数

一、客户端和服务器传输数据的类

1、后台程序发送HTTP请求的Class，服务器端也要添加该类

namespace WebApiInvoke
{
    /// <summary>
    /// 后台程序发送HTTP请求数据的类
    /// </summary>
    class RequestDataModel
    {
        /// <summary>
        /// 姓名
        /// </summary>
        public string DataName { get; set; }
        /// <summary>
        /// 性别
        /// </summary>
        public string DataSex { get; set; }
        /// <summary>
        /// 结果
        /// </summary>
        public string DataResult { get; set; }
        /// <summary>
        /// 年龄
        /// </summary>
        public int DataAge { get; set; }
    }
}

2、服务端返回HTTP请求的数据class，客户端也要有

namespace ServiceTest
{
    /// <summary>
    /// WebService 服务端返回的类
    /// </summary>
    public class WebServiceWriteBack
    {
        public bool Success { get; set; } = true;
        public string Data { get; set; } = string.Empty;
    }
}

二、“application/json”：

1、后台程序(客户端)发送HTTP请求(request.Method = “POST”、request.ContentType = “application/json”),

a.客户端代码：

namespace WebApiInvoke
{
    class HttpApiRequestHelper
    {
        /// <summary>
        /// 使用HttpWebRequest发送一个POST请求 
        /// </summary>
        /// <param name="url">请求的地址</param>
        /// <param name="dto">发送的数据对象</param>
        /// <returns></returns>
        public static string HttpJsonPost(string url, object dto)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

            request.Method = "POST";
            request.KeepAlive = false;
            request.AllowAutoRedirect = true;
            request.Accept = "application/json";
            request.ContentType = "application/json";
            string strContent = JsonConvert.SerializeObject(dto); //序列化为字符串，可以使用自己项目中封装的json方法
            using (StreamWriter dataStream = new StreamWriter(request.GetRequestStream()))
            {
                dataStream.Write(strContent);
            }
            //  获取服务器返回的响应体
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string encoding = response.ContentEncoding;
            if (encoding == null || encoding.Length < 1)
            {
                encoding = "UTF-8"; //默认编码  
            }
            StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding(encoding));
            string retString = reader.ReadToEnd();
            return retString;
        }
   	}
}

服务器端通过Request.InputStream获取json数据，并做相应的处理；
需要NuGet程序包中安装Microsoft.AspNetCore.Mvc.WebApiCompatShim，并usingSystem.Web.Http;

b.服务器端对应的代码

using Newtonsoft.Json;
using System;
using System.IO;
using System.Web;
using System.Web.Http;

namespace ServiceTest
{
    /// WebService 接口 通过Request请求获取json参数
    class GetRequestDataHelper : ApiController
    {
        /// <summary>
        /// 通过Request请求获取json参数
        /// 对应request.ContentType = "application/json"
        /// </summary>
        /// <returns></returns>
        public WebServiceWriteBack GetRequestJsonData()
        {
        	// 服务器端回写数据库的类
            WebServiceWriteBack writeBack = new WebServiceWriteBack();
            HttpContextBase context = Request.Properties["MS_HttpContext"] as HttpContextBase;
            HttpRequestBase request = context.Request;

            string data = string.Empty;
            using (Stream stream = request.InputStream)// 读取Json数据
            {
                stream.Position = 0;
                using (StreamReader streamReader = new StreamReader(stream))
                {
                    data = streamReader.ReadToEnd();
                }
            }
            // 将Json数据转换为对象
            RequestDataModel data1 = JsonConvert.DeserializeObject<RequestDataModel>(data);
            #region 对传进来的 DataModel 进行处理 并对要回写的WebServiceWriteBack类进行赋值
            if (string.IsNullOrEmpty(data1.DataSex))
            {
                writeBack.Success = true;
                writeBack.Data = "成功了！";
            }
            #endregion

            return writeBack;
        }
    }
}

三、表单：

1、传统的表单数据是"DataName=1&DataSex=dadada&DataResult=S201FR&DataAge=1"一个字符串中间用‘&’分割；

后台程序(客户端)发送HTTP请求(request.Method = “POST”、request.ContentType = “application/x-www-form-urlencoded”),

a.客户端代码：

        /// <summary>
        /// HttpWebRequest Post请求
        /// application/x-www-form-urlencoded
        /// "DataName=1&DataSex=dadada&DataResult=S201FR&DataAge=1"
        /// </summary>
        /// <param name="postUrl">请求地址</param>
        /// <param name="postData">请求参数(json格式请求数据时contentType必须指定为application/json)</param>
        /// <param name="result">返回结果</param>
        /// <param name="contentType">请求类型</param>
        /// <returns>返回结果</returns>
        public static bool WebHttpPost(string postUrl, string postData, out string result, string contentType = "application/x-www-form-urlencoded")
        {
            try
            {
                Encoding encoding = Encoding.GetEncoding("gb2312");
                byte[] byteArray = encoding.GetBytes(postData);

                HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(postUrl);
                httpWebRequest.Method = "POST";
                httpWebRequest.ContentType = contentType;
                httpWebRequest.ContentLength = byteArray.Length;
                httpWebRequest.AllowAutoRedirect = true;

                using (Stream stream = httpWebRequest.GetRequestStream())
                {
                    stream.Write(byteArray, 0, byteArray.Length); // 写入参数                  
                }
				//  获取服务器返回的响应体
                HttpWebResponse httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse;
                using (Stream responseStream = httpWebResponse.GetResponseStream())
                {
                    StreamReader streamReader = new StreamReader(responseStream, Encoding.GetEncoding("UTF-8"));
                    result = streamReader.ReadToEnd(); // 请求返回的数据
                    streamReader.Close();
                }

                return true;
            }
            catch (Exception ex)
            {
                result = ex.Message;
                return false;
            }
        }

b.服务器端通过Request.Form获取表单数据，并做相应的处理；

using Newtonsoft.Json;
using System;
using System.IO;
using System.Web;
using System.Web.Http;

namespace ServiceTest
{
        /// <summary>
        /// 通过Request请求获取表单参数
        /// 对应contentType = "application/x-www-form-urlencoded"和contentType =  "multipart/form-data"
        /// </summary>
        /// <returns></returns>

        public WebServiceWriteBack GetRequestFromData()
        {
            // 服务器端回写数据库的类
            WebServiceWriteBack writeBack = new WebServiceWriteBack();
            HttpContextBase context = Request.Properties["MS_HttpContext"] as HttpContextBase;
            HttpRequestBase request = context.Request;
            
            RequestDataModel data1 = new RequestDataModel()
            {
                DataName = request.Form["DataName"]?.ToString(),
                DataSex = request.Form["DataSex"]?.ToString(),
                DataAge = Convert.ToInt32(request.Form["DataAge"]?.ToString()),
                DataResult = request.Form["DataResult"]?.ToString()
            };
            #region 对传进来的 DataModel 进行处理 并对要回写的WebServiceWriteBack类进行赋值
            if (string.IsNullOrEmpty(data1.DataSex))
            {
                writeBack.Success = true;
                writeBack.Data = "成功了！";
            }
            #endregion

            return writeBack;
        }
    }
}

2、“multipart/form-data”

包含异步请求方法HttpPostAsync和HttpPostFromData方法文章来源地址https://www.toymoban.com/news/detail-740551.html

a.客户端代码，两个方法

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;

namespace WebApiInvoke
{
    class HttpApiRequestHelper
    {
        /// <summary>
        /// Async异步请求 POST
        /// </summary>
        /// <param name="urlStr">请求的地址</param>
        /// <param name="jsonStr">Json字符串</param>
        /// <returns></returns>
        public static string HttpPostAsync(string urlStr, string jsonStr)
        {
            string content = "";
            try
            {
                Dictionary<string, string> map = JsonStringToKeyValuePairs(jsonStr);

                var mfdc = new System.Net.Http.MultipartFormDataContent();
                mfdc.Headers.Add("ContentType", "multipart/form-data");//声明头部
                foreach (string key in map.Keys)
                {
                    mfdc.Add(new System.Net.Http.StringContent(map[key]), key);//参数, 内容在前,参数名称在后
                }
                var clientTask = new System.Net.Http.HttpClient().PostAsync(urlStr, mfdc);//发起异步请求
                clientTask.Wait();//等待请求结果
                if (clientTask.Result.IsSuccessStatusCode)
                {
                    //请求正常
                    var resultTask = clientTask.Result.Content.ReadAsStringAsync();//异步读取返回内容
                    resultTask.Wait();//等读取返回内容
                    content = resultTask.Result;//返回内容字符串
                }
                else
                {
                    //请求异常
                    content = "失败";
                }
            }
            catch (Exception ex)
            {
                content = ex.Message;
            }
            return content;
        }

        /// <summary>
        /// multipart/form-data POST请求
        /// </summary>
        /// <param name="url">请求的地址</param>
        /// <param name="jsonStr">Json字符串</param>
        /// <returns></returns>
        public static string HttpPostFromData(string url, string jsonStr)
        {
            string content = "";
            try
            {
                string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
                byte[] boundarybytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
                byte[] endbytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");

                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
                request.ContentType = "multipart/form-data; boundary=" + boundary;
                request.Method = WebRequestMethods.Http.Post;
                request.KeepAlive = true;
                request.Timeout = -1;

                CredentialCache credentialCache = new CredentialCache();
                credentialCache.Add(new Uri(url), "Basic", new NetworkCredential("user", "user"));
                request.Credentials = credentialCache;

                request.ServicePoint.Expect100Continue = false;
                Dictionary<string, string> map = JsonStringToKeyValuePairs(jsonStr);
                using (Stream stream = request.GetRequestStream())
                {
                    //1.1 key/value
                    string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
                    if (map != null)
                    {
                        foreach (string key in map.Keys)
                        {
                            stream.Write(boundarybytes, 0, boundarybytes.Length);
                            string formitem = string.Format(formdataTemplate, key, map[key]);
                            byte[] formitembytes = Encoding.GetEncoding("UTF-8").GetBytes(formitem);
                            stream.Write(formitembytes, 0, formitembytes.Length);
                        }
                    }
                    stream.Write(endbytes, 0, endbytes.Length);
                }
                //2.WebResponse
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                using (Stream responsestream = response.GetResponseStream())
                {
                    using (StreamReader sr = new StreamReader(responsestream))
                    {
                        content = sr.ReadToEnd();
                    }
                }
            }
            catch (Exception ex)
            {
                content = ex.Message;
            }
            return content;
        }

        /// <summary>
        /// JSON格式转Dictionary
        /// </summary>
        /// <param name="jsonStr"></param>
        /// <returns></returns>
        public static Dictionary<string, string> JsonStringToKeyValuePairs(string jsonStr)
        {
            char jsonBeginToken = '{';
            char jsonEndToken = '}';

            if (string.IsNullOrEmpty(jsonStr))
            {
                return null;
            }
            //验证json字符串格式
            if (jsonStr[0] != jsonBeginToken || jsonStr[jsonStr.Length - 1] != jsonEndToken)
            {
                throw new ArgumentException("非法的Json字符串!");
            }

            var resultDic = new Dictionary<string, string>();
            var jobj = JObject.Parse(jsonStr);
            JsonOn(jobj, resultDic);
            return resultDic;
        }

        private static Dictionary<string, string> JsonOn(JToken jobT, Dictionary<string, string> Dic)
        {

            //找出包含嵌套的字段列
            if (jobT is JObject jobj && jobj.Properties().Count() > 0)
            {
                foreach (var item in jobj.Properties())
                {
                    JsonProperties(item, Dic);
                }
            }
            else
            {
                Dic.Add(jobT.Path, jobT.ToString());

                return Dic;
            }
            return Dic;
        }

        private static Dictionary<string, string> JsonProperties(JProperty jobj, Dictionary<string, string> Dic)
        {
            return JsonOn(jobj.Value, Dic);
        }

    }
}

b. 服务器方法同1.b 这里不再赘述

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