c# 获取cook

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;

namespace HQTX_BatchAddData
{
    /// <summary>
    /// WinInet.dll wrapper
    /// </summary>
    internal static class CookieReader
    {

        private const int INTERNET_COOKIE_HTTPONLY = 0x00002000;

        [DllImport("wininet.dll", SetLastError = true)]
        private static extern bool InternetGetCookieEx(
            string url,
            string cookieName,
            StringBuilder cookieData,
            ref int size,
            int flags,
            IntPtr pReserved);
        public static string GetCookie(string url)
        {
            int size = ;
            StringBuilder sb = new StringBuilder(size);
            if (!InternetGetCookieEx(url, null, sb, ref size, INTERNET_COOKIE_HTTPONLY, IntPtr.Zero))
            {
                if (size < )
                {
                    return null;
                }
                sb = new StringBuilder(size);
                if (!InternetGetCookieEx(url, null, sb, ref size, INTERNET_COOKIE_HTTPONLY, IntPtr.Zero))
                {
                    return null;
                }
            }
            return sb.ToString();
        }
    }
}