ASP.NET Core使用HttpClient的同步和异步请求

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web;

namespace Common
{
    public class HttpHelper
    {/// <summary>
        /// 发起POST同步请求
        ///
        /// </summary>
        /// <param name="url"></param>
        /// <param name="postData"></param>
        /// <param name="contentType">application/xml、application/json、application/text、application/x-www-form-urlencoded</param>
        /// <param name="headers">填充消息头</param>
        /// <returns></returns>
        public static string HttpPost(string url, string postData = null, string contentType = null, int timeOut = , Dictionary<string, string> headers = null)
        {
            postData = postData ?? "";
            using (HttpClient client = new HttpClient())
            {
                if (headers != null)
                {
                    foreach (var header in headers)
                        client.DefaultRequestHeaders.Add(header.Key, header.Value);
                }
                using (HttpContent httpContent = new StringContent(postData, Encoding.UTF8))
                {
                    if (contentType != null)
                        httpContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);

                    HttpResponseMessage response = client.PostAsync(url, httpContent).Result;
                    return response.Content.ReadAsStringAsync().Result;
                }
            }
        }

        /// <summary>
        /// 发起POST异步请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="postData"></param>
        /// <param name="contentType">application/xml、application/json、application/text、application/x-www-form-urlencoded</param>
        /// <param name="headers">填充消息头</param>
        /// <returns></returns>
        public static async Task<string> HttpPostAsync(string url, string postData = null, string contentType = null, int timeOut = , Dictionary<string, string> headers = null)
        {
            postData = postData ?? "";
            using (HttpClient client = new HttpClient())
            {
                client.Timeout = new TimeSpan(, , timeOut);
                if (headers != null)
                {
                    foreach (var header in headers)
                        client.DefaultRequestHeaders.Add(header.Key, header.Value);
                }
                using (HttpContent httpContent = new StringContent(postData, Encoding.UTF8))
                {
                    if (contentType != null)
                        httpContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);

                    HttpResponseMessage response = await client.PostAsync(url, httpContent);
                    return await response.Content.ReadAsStringAsync();
                }
            }
        }

        /// <summary>
        /// 发起GET同步请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="headers"></param>
        /// <param name="contentType"></param>
        /// <returns></returns>
        public static string HttpGet(string url, Dictionary<string, string> headers = null)
        {
            using (HttpClient client = new HttpClient())
            {if (headers != null)
                {
                    foreach (var header in headers)
                        client.DefaultRequestHeaders.Add(header.Key, header.Value);
                }
                HttpResponseMessage response = client.GetAsync(url).Result;
                return response.Content.ReadAsStringAsync().Result;
            }
        }

        /// <summary>
        /// 发起GET异步请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="headers"></param>
        /// <param name="contentType"></param>
        /// <returns></returns>
        public static async Task<string> HttpGetAsync(string url, Dictionary<string, string> headers = null)
        {
            using (HttpClient client = new HttpClient())
            {if (headers != null)
                {
                    foreach (var header in headers)
                        client.DefaultRequestHeaders.Add(header.Key, header.Value);
                }
                HttpResponseMessage response = await client.GetAsync(url);
                return await response.Content.ReadAsStringAsync();
            }
        }
    }
}

调用异步请求方法：

var result = await HttpHelper.HttpPostAsync("http://www.baidu.com/api/getuserinfo", "userid=23456798");