C# 后端调用 Web API

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

namespace ZB.QueueSys.Common
{
    public class WebApiHelper
    {
        private static WebApiHelper instance;
        public static WebApiHelper Instance
        {
            get
            {
                if (instance == null) instance = new WebApiHelper();
                return WebApiHelper.instance;
            }
        }

        public string HttpGet(string url)
        {
            //string ss = HttpGet("http://localhost:000/api/Demo/GetXXX?Name=北京");
            //ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
            Encoding encoding = Encoding.UTF8;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "GET";
            request.Accept = "text/html, application/xhtml+xml, */*";
            request.ContentType = "application/json";

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

        public string HttpPost(string url, string body)
        {
            //string ss = HttpPost("http://localhost:000/api/Demo/PostXXX", "{Code:"test089",Name:"test1"}");
            //ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
            Encoding encoding = Encoding.UTF8;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "POST";
            request.Accept = "text/html, application/xhtml+xml, */*";
            request.ContentType = "application/json";

            byte[] buffer = encoding.GetBytes(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();
            }
        }


    }
}