C#

 WebRequest方式

•  封装的方法

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

namespace CallWebApi
{
    /// <summary>
    /// 调用外部API
    /// </summary>
    public static class CallExternalAPI
    {
        /// <summary>
        /// WebRequest方式
        /// </summary>
        /// <returns></returns>
        public static string HttpPost(string url, Dictionary<string, object> body = null, Dictionary<string, string> header = null)
        {
            string result;
            try
            {
                Encoding encoding = Encoding.UTF8;
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.Method = "POST";
                request.Accept = "text/html, application/xhtml+xml, */*";
                request.ContentType = "application/json";
                if (header != null)
                {
                    foreach (var item in header)
                    {
                        request.Headers.Add(item.Key, item.Value);
                    }
                }
                if (body != null)
                {
                    byte[] buffer = encoding.GetBytes(JsonConvert.SerializeObject(body));
                    request.ContentLength = buffer.Length;
                    request.GetRequestStream().Write(buffer, 0, buffer.Length);
                }
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
                {
                    return reader.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                result = ex.Message;
            }
            return result;
        }

        /// <summary>
        /// HttpWebRequest方式
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static string HttpGet(string url, Dictionary<string, string> header = null)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "GET";
            request.Accept = "text/html, application/xhtml+xml, */*";
            request.ContentType = "application/json";
            if (header != null)
            {
                foreach (var item in header)
                {
                    request.Headers.Add(item.Key, item.Value);
                }
            }

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            {
                return reader.ReadToEnd();
            }
        }
    }
}

•  调用方式using Newtonsoft.Json;

using System;
using System.Collections.Generic;

namespace CallWebApi
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("开始测试：");

            #region HttpWebRequest方式
            string result0 = CallExternalAPI.HttpPost("http://localhost:8500/api/employee/post-no");
            Console.WriteLine(result0);

            Dictionary<string, object> body1 = new Dictionary<string, object>
            {
                { "name", "12d" }
            };
            string result1 = CallExternalAPI.HttpPost("http://localhost:8500/api/employee/post", body1);
            Console.WriteLine(result1);

            Dictionary<string, string> header2 = new Dictionary<string, string>
            {
                { "token", "12d" }
            };
            Dictionary<string, object> body2 = new Dictionary<string, object>
            {
                { "name", "12d" }
            };
            string result2 = CallExternalAPI.HttpPost("http://localhost:8500/api/employee/post-token", body2, header2);
            Console.WriteLine(result2);

            string result3 = CallExternalAPI.HttpGet("http://localhost:8500/api/employee/list");
            Console.WriteLine(result3);

            string result4 = CallExternalAPI.HttpGet("http://localhost:8500/api/employee/get-yes?id=12");
            Console.WriteLine(result4);

            Dictionary<string, string> header5 = new Dictionary<string, string>
            {
                { "token", "12d" }
            };
            string result5 = CallExternalAPI.HttpGet("http://localhost:8500/api/employee/get?id=12", header5);
            Console.WriteLine(result5);
            #endregion
        }
    }
}

 HttpClient方式

•  封装的方法

using Newtonsoft.Json;
using System.Collections.Generic;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace CallWebApi
{
    /// <summary>
    /// HttpClient方式
    /// </summary>
    public static class HttpClientHelper
    {
        public static HttpClient HttpClient { get; set; }

        static HttpClientHelper()
        {
            //单例模式
            if (HttpClient == null)
            {
                HttpClient = new HttpClient();
            }

            HttpClient.DefaultRequestHeaders.Accept.Clear();
            HttpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            //能解读https类型
            //ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
        }

        /// <summary>
        /// Get方法
        /// </summary>
        /// <param name="url">目标链接(含参数)</param>
        /// <returns>返回的字符串</returns>
        public static async Task<string> GetAsync(string url, Dictionary<string, string> header = null)
        {
            if (header != null)
            {
                foreach (var item in header)
                {
                    HttpClient.DefaultRequestHeaders.Add(item.Key, item.Value);
                }
            }
            using (HttpResponseMessage response = await HttpClient.GetAsync(url))
            {
                response.EnsureSuccessStatusCode();
                string result = await response.Content.ReadAsStringAsync();
                return result;
            }
        }

        /// <summary>
        /// Post方法
        /// </summary>
        /// <param name="url">目标链接</param>
        /// <param name="body"></param>
        /// <param name="header"></param>
        /// <returns>返回的字符串</returns>
        public static async Task<string> PostAsync(string url, Dictionary<string, object> body = null, Dictionary<string, string> header = null)
        {
            if (header != null)
            {
                foreach (var item in header)
                {
                    HttpClient.DefaultRequestHeaders.Add(item.Key, item.Value);
                }
            }

            StringContent content = new StringContent(JsonConvert.SerializeObject(body));
            content.Headers.ContentType = new MediaTypeHeaderValue("application/json");

            using (HttpResponseMessage response = await HttpClient.PostAsync(url, content))
            {
                response.EnsureSuccessStatusCode();
                string result = await response.Content.ReadAsStringAsync();
                return result;
            }
        }

        /// <summary>
        /// Post方法
        /// </summary>
        /// <param name="url">目标链接</param>
        /// <param name="json">发送的json格式的参数字符串</param>
        /// <returns>返回的字符串</returns>
        public static async Task<string> PostAsync(string url, HttpContent content)
        {
            //HttpContent content = new FormUrlEncodedContent(new Dictionary<string, string>()
            //       {
            //           { "token", token},
            //           { "orderNo", orderNo}
            //       });
            content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded") { CharSet = "utf-8" };

            using (HttpResponseMessage response = await HttpClient.PostAsync(url, content))
            {
                response.EnsureSuccessStatusCode();
                string result = await response.Content.ReadAsStringAsync();
                return result;
            }
        }
    }
}

•  调用方式

using Newtonsoft.Json;
using System;
using System.Collections.Generic;

namespace CallWebApi
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("开始测试：");

            string result0 = HttpClientHelper.PostAsync("http://localhost:8500/api/employee/post-no").Result;
            Console.WriteLine(result0);

            Dictionary<string, object> body1 = new Dictionary<string, object>
            {
                { "name", "12d" }
            };
            string result1 = HttpClientHelper.PostAsync("http://localhost:8500/api/employee/post", body1).Result;
            Console.WriteLine(result1);

            Dictionary<string, string> header2 = new Dictionary<string, string>
            {
                { "token", "12d" }
            };
            Dictionary<string, object> body2 = new Dictionary<string, object>
            {
                { "name", "12d" }
            };
            string result2 = HttpClientHelper.PostAsync("http://localhost:8500/api/employee/post-token", body2, header2).Result;
            Console.WriteLine(result2);



            string result3 = HttpClientHelper.GetAsync("http://localhost:8500/api/employee/list").Result;
            Console.WriteLine(result3);

            string result4 = HttpClientHelper.GetAsync("http://localhost:8500/api/employee/get-yes?id=12").Result;
            Console.WriteLine(result4);

            Dictionary<string, string> header5 = new Dictionary<string, string>
            {
                { "token", "12d" }
            };
            string result5 = HttpClientHelper.GetAsync("http://localhost:8500/api/employee/get?id=12", header5).Result;
            Console.WriteLine(result5);
        }
    }
}