/// <summary>
        /// post请求方式
        /// </summary>
        /// <param name="url">请求路径</param>
        /// <param name="parms">传入的值，格式为：{city:"上海"，city2:"重庆"}</param>
        /// <param name="token"></param>
        /// <param name="ContentType"></param>
        /// <returns></returns>
        public string HttpPost(string url, string parms, string token,string ContentType= "application/json")
        {
            string result = string.Empty;
            try
            {
                if (url.StartsWith("https:"))
                {
                    //要调用https的API接口，一定要加这句
                    ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
                }
                Encoding encoding = Encoding.UTF8;  //转译编码
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);//创建
                request.Method = "POST";   //post请求的一些标准参数配置
                request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
                request.ContentType = ContentType;
                //自定义头部内容
                if (!string.IsNullOrEmpty(token))
                {
                    request.Headers.Add(HttpRequestHeader.Authorization, token);  //添加token
                }
                byte[] buffer = encoding.GetBytes(parms);  //译编传入的值格式化为可识别
                request.ContentLength = buffer.Length;  //post传值参数标配
                request.GetRequestStream().Write(buffer, 0, buffer.Length);
                HttpWebResponse response = (HttpWebResponse)request.GetResponse(); //尝试获得要请求的URL的返回消息
                using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
                {
                    result = reader.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                result = "";
            }
            return result;
        }

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
namespace TranslateProject
{
    class Program
    {
        // 百度云中开通对应服务应用的 API Key 建议开通应用的时候多选服务(百度云应用的AK)
        private static String clientId = "qNldYXXtIr2pKBQsv242369Y";
        // 百度云中开通对应服务应用的 Secret Key(百度云应用的SK)
        private static String clientSecret = "L6gemOD3pM2PmafyQUBnXpCGEemk18mR";
        static void Main(string[] args)
        {
            try
            {
                #region 文本翻译-通用版
                //获取Token：详细见 https://ai.baidu.com/ai-doc/REFERENCE/Ck3dwjhhu
                string TokenJson = getAccessToken();
                if (!string.IsNullOrEmpty(TokenJson))
                {
                    AccessToken TokenEntity = JsonConvert.DeserializeObject<AccessToken>(TokenJson);
                    if (!string.IsNullOrEmpty(TokenEntity.error))
                    {
                        if (TokenEntity.error == "invalid_client" && TokenEntity.error_description == "unknown client id")
                            Console.WriteLine("API Key不正确");
                        else if (TokenEntity.error == "invalid_client" && TokenEntity.error_description == "Client authentication failed")
                            Console.WriteLine("Secret Key不正确");
                        else
                            Console.WriteLine("未知错误：获取Token失败");
                        Console.ReadKey();
                        return;
                    }
                    string URL = "https://aip.baidubce.com/rpc/2.0/mt/texttrans/v1?access_token="+ TokenEntity.access_token;
                    string q = "文本翻译是百度翻译依托领先的自然语言处理技术推出的在线文本翻译服务，可支持中、英、日、韩等200+语言互译，100+语种自动检测。";
                    string parms = "{ \"q\":\"" + q + "\",\"from\":\"zh\",\"to\":\"en\"}"; //from：翻译源语言     to：翻译目标语言     q：请求翻译内容
                    HttpTool httppost = new HttpTool();
                    var strJson = httppost.HttpPost(URL, parms, "", "application/json;charset=utf-8");
                    Console.WriteLine(strJson);
                    Console.ReadKey();
                }
                #endregion
            }
            catch (Exception ex)
            {
                Console.WriteLine("翻译失败：" + ex.Message);
            }
        }
        //调用getAccessToken()获取的 access_token建议根据expires_in 时间 设置缓存
        public static String getAccessToken()
        {
            try
            {
                String authHost = "https://aip.baidubce.com/oauth/2.0/token";
                HttpClient client = new HttpClient();
                List<KeyValuePair<String, String>> paraList = new List<KeyValuePair<string, string>>();
                paraList.Add(new KeyValuePair<string, string>("grant_type", "client_credentials"));
                paraList.Add(new KeyValuePair<string, string>("client_id", clientId));
                paraList.Add(new KeyValuePair<string, string>("client_secret", clientSecret));
                HttpResponseMessage response = client.PostAsync(authHost, new FormUrlEncodedContent(paraList)).Result;
                String result = response.Content.ReadAsStringAsync().Result;
                return result;
            }
            catch (Exception ex)
            {
                return "";
            }
        }
        public class AccessToken
        {
            public string refresh_token { get; set; }
            public int expires_in { get; set; }
            public string scope { get; set; }
            public string session_key { get; set; }
            public string access_token { get; set; }
            public string session_secret { get; set; }
            public string error { get; set; }
            public string error_description { get; set; }
        }
    }
}