C# implements the image's suffix name based on the image's link address

using System;
using ;
using ;
using ;
using ;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            var imgUrl = "/wx_emoji/haiannhLHhY7B1tX6eZ2BGNh9kzx3VCQ2MJfSQkSgE47sEXofVVoPCiaZKYbPcyQhS/";
            var imgByte = GetBytesFromUrl(imgUrl);
            if ( > 0)
            {
                var image = BytesToImage(imgByte);
                if (image != null)
                {
                    var mimeType = GetMimeType(image);
                    if (!(mimeType))
                    {
                        var fileName =  + "\\imgses\\" + ("yyyyMMddHHmmssfff") + "." + mimeType;
                        CreateImageFromBytes(fileName, imgByte);
                    }
                }
            }
        }

        /// <summary>
        /// Convert http path image to byte data        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static byte[] GetBytesFromUrl(string url)
        {
            HttpWebRequest request = (HttpWebRequest)(url);

            byte[] bytes;
            using (Stream stream = ().GetResponseStream())
            {
                using (MemoryStream mstream = new MemoryStream())
                {
                    int count = 0;
                    byte[] buffer = new byte[1024];
                    int readNum = 0;
                    while ((readNum = (buffer, 0, 1024)) > 0)
                    {
                        count = count + readNum;
                        (buffer, 0, readNum);
                    }
                     = 0;
                    using (BinaryReader br = new BinaryReader(mstream))
                    {
                        bytes = (count);
                    }
                }
            }
            return bytes;
        }

        /// <summary>
        /// Convert byte byte data to Image image        /// </summary>
        /// <param name="bytes">Byte array</param>        /// <returns>Picture</returns>        public static Image BytesToImage(byte[] bytes)
        {
            Image image = null;
            using (MemoryStream ms = new MemoryStream(bytes))
            {
                (bytes, 0, );
                image = (ms, true);
            }
            return image;
        }
        
        /// &lt;summary&gt;
        /// Convert Image image to byte data        /// &lt;/summary&gt;
        /// &lt;param name="image"&gt;&lt;/param&gt;
        /// &lt;returns&gt;&lt;/returns&gt;
        public static byte[] ImageToBytes(Image image)
        {
            byte[] bt = null;
            if (!(null))
            {
                using (MemoryStream mostream = new MemoryStream())
                {
                    Bitmap bmp = new Bitmap(image);
                    (mostream, );//Storing the image into the cache memory stream in the specified format                    bt = new byte[];
                     = 0;//Set the initial position to be left                    (bt, 0, Convert.ToInt32());
                }
            }
            return bt;
        }

        /// &lt;summary&gt;
        /// Get the image type according to the Image image        /// &lt;/summary&gt;
        /// &lt;param name="image"&gt;&lt;/param&gt;
        /// &lt;returns&gt;&lt;/returns&gt;
        public static string GetMimeType(Image image)
        {
            var mimeType = "";
            var ImageCodec = ();
            foreach (var item in ImageCodec)
            {
                if ( == )
                {
                    mimeType = ('/')[1];
                    break;
                }
            }
            return mimeType;
        }

        /// &lt;summary&gt;
        /// Save the byte[] image to the specified file        /// &lt;/summary&gt;
        /// <param name="fileName">Full path saved (including file name)</param>        /// &lt;param name="bytes"&gt;&lt;/param&gt;
        /// &lt;returns&gt;&lt;/returns&gt;
        public static void CreateImageFromBytes(string fileName, byte[] bytes)
        {
            string file = fileName;
            FileInfo info = new FileInfo(fileName);
            ();
            (file, bytes);
        }
    }
}