using System;

using System.Drawing;

using System.Drawing.Imaging;

using System.IO;

using System.Net;

namespace ConsoleApp3

{

    class Program

    {

        static void Main(string[] args)

        {

            var imgUrl = "http://emoji.qpic.cn/wx_emoji/haiannhLHhY7B1tX6eZ2BGNh9kzx3VCQ2MJfSQkSgE47sEXofVVoPCiaZKYbPcyQhS/";

            var imgByte = GetBytesFromUrl(imgUrl);

            if (imgByte.Length > 0)

            {

                var image = BytesToImage(imgByte);

                if (image != null)

                {

                    var mimeType = GetMimeType(image);

                    if (!string.IsNullOrEmpty(mimeType))

                    {

                        var fileName = AppDomain.CurrentDomain.BaseDirectory + "\\imgses\\" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + "." + mimeType;

                        CreateImageFromBytes(fileName, imgByte);

                    }

                }

            }

        }

        /// <summary>

        /// 将http路径图片转为byte字节数据

        /// </summary>

        /// <param name="url"></param>

        /// <returns></returns>

        public static byte[] GetBytesFromUrl(string url)

        {

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

            byte[] bytes;

            using (Stream stream = request.GetResponse().GetResponseStream())

            {

                using (MemoryStream mstream = new MemoryStream())

                {

                    int count = 0;

                    byte[] buffer = new byte[1024];

                    int readNum = 0;

                    while ((readNum = stream.Read(buffer, 0, 1024)) > 0)

                    {

                        count = count + readNum;

                        mstream.Write(buffer, 0, readNum);

                    }

                    mstream.Position = 0;

                    using (BinaryReader br = new BinaryReader(mstream))

                    {

                        bytes = br.ReadBytes(count);

                    }

                }

            }

            return bytes;

        }

        /// <summary>

        /// 将byte字节数据转为Image图片

        /// </summary>

        /// <param name="bytes">字节数组</param>

        /// <returns>图片</returns>

        public static Image BytesToImage(byte[] bytes)

        {

            Image image = null;

            using (MemoryStream ms = new MemoryStream(bytes))

            {

                ms.Write(bytes, 0, bytes.Length);

                image = Image.FromStream(ms, true);

            }

            return image;

        }

        /// <summary>

        /// 将Image图片转为byte字节数据

        /// </summary>

        /// <param name="image"></param>

        /// <returns></returns>

        public static byte[] ImageToBytes(Image image)

        {

            byte[] bt = null;

            if (!image.Equals(null))

            {

                using (MemoryStream mostream = new MemoryStream())

                {

                    Bitmap bmp = new Bitmap(image);

                    bmp.Save(mostream, ImageFormat.Bmp);//将图像以指定的格式存入缓存内存流

                    bt = new byte[mostream.Length];

                    mostream.Position = 0;//设置留的初始位置

                    mostream.Read(bt, 0, Convert.ToInt32(bt.Length));

                }

            }

            return bt;

        }

        /// <summary>

        /// 根据Image图片获取图片类型

        /// </summary>

        /// <param name="image"></param>

        /// <returns></returns>

        public static string GetMimeType(Image image)

        {

            var mimeType = "";

            var ImageCodec = ImageCodecInfo.GetImageDecoders();

            foreach (var item in ImageCodec)

            {

                if (item.FormatID == image.RawFormat.Guid)

                {

                    mimeType = item.MimeType.Split('/')[1];

                    break;

                }

            }

            return mimeType;

        }

        /// <summary>

        /// 将byte[]图片保存到指定文件

        /// </summary>

        /// <param name="fileName">保存的完整路径（包含文件名）</param>

        /// <param name="bytes"></param>

        /// <returns></returns>

        public static void CreateImageFromBytes(string fileName, byte[] bytes)

        {

            string file = fileName;

            FileInfo info = new FileInfo(fileName);

            Directory.CreateDirectory(info.Directory.FullName);

            File.WriteAllBytes(file, bytes);

        }

    }

}