.net 根据图片网络地址获取图片二进制字节数据流

根据html路径获取图片的字节

        /// <summary>
        ///根据html路径获取图片的字节
        /// </summary> 
        /// <param name="picSize">图片尺寸,原图：1，大图：2，中图：3，小图：4</param> 
        /// <param name="serverPath">图片服务器地址</param>
        /// <returns></returns>
        public static byte[] GetImageByteByHtmlImgUrl(string imgSize, string serverPath)
        {
            byte[] bt = new byte[4096];

            try
            {
                serverPath = serverPath.Replace("_1.", string.Format("_{0}.", imgSize));
                Image obj = Image.FromStream(System.Net.WebRequest.Create(serverPath).GetResponse().GetResponseStream());
                bt = ImageToByteArray(obj);  //使用ImageToByteArray()函数 将Image类型转成Byte[]类型
                obj.Dispose();
                return bt;
            }
            catch  //如果获取异常 则使用资源中的图片显示 
            {
                //Image obj = Image.FromStream("");
                //byte[] bt = ImageToByteArray(obj);
                //obj.Dispose();
                //return bt;
            }

            return bt;
        }

关键代码：

Image obj = Image.FromStream(System.Net.WebRequest.Create(serverPath).GetResponse().GetResponseStream());

从网络上先存储成本地图片，再从本地图片中转成二进制数据流

 /// <summary>
        /// 获取商品图片的二进制数据流
        /// </summary>
        /// <param name="picSize">图片尺寸,原图：1，大图：2，中图：3，小图：4</param>
        /// <param name="filePath">本地路径</param>
        /// <param name="serverPath">图片服务器地址</param>
        public static byte[] GetServerFile(string picSize, string filePath, string serverPath)
        {
            byte[] buffer = new byte[4096];

            System.Net.HttpWebRequest hr;
            FileStream fs = null;
            Stream s = null;

            try
            {
                filePath = System.IO.Directory.GetCurrentDirectory() + "\" + "byteimg" + "\" + filePath;

                filePath = filePath.Replace("_1.", string.Format("_{0}.", picSize));

                hr = (HttpWebRequest)HttpWebRequest.Create(serverPath);


                if (!File.Exists(filePath))
                {
                    string path = System.IO.Path.GetDirectoryName(filePath);
                    if (!Directory.Exists(path))
                    {
                        Directory.CreateDirectory(path);
                    }
                    //  _FileDir = str;

                    //  Flag = G_Method.GetServerFile(LoadFileName, _ImageAddress + NVRGoodsImageFile.Replace("\", "//"));
                }

                //if (File.Exists(filePath))
                //{
                //    return true;
                //}

                fs = new FileStream(filePath, FileMode.Create);
                s = hr.GetResponse().GetResponseStream();


                int bytesRead = s.Read(buffer, 0, buffer.Length);
                while (bytesRead > 0)
                {
                    fs.Write(buffer, 0, bytesRead);
                    bytesRead = s.Read(buffer, 0, buffer.Length);
                }
                // return true;
            }
            catch (Exception e)
            {
                //throw new ApplicationException("Could not download file " + serverPath, e);
                // return false;
            }
            finally
            {
                if (s != null)
                    s.Close();
                if (fs != null)
                    fs.Close();
            }

            return buffer;
        }

Code By 博客园-曹永思

根据image获取图片的字节

        /// <summary>
        /// 根据image获取图片的字节
        /// </summary>
        /// <param name="image"></param>
        /// <returns></returns>
        private static byte[] ImageToByteArray(Image image)
        {
            System.IO.MemoryStream mStream = new System.IO.MemoryStream();
            image.Save(mStream, System.Drawing.Imaging.ImageFormat.Png);
            byte[] ret = mStream.ToArray();
            mStream.Close();
            return ret;
        }

根据图片字节流获取Image实例

        /// <summary>
        /// 根据图片字节流获取Image实例
        /// </summary>
        /// <param name="imagebyte"></param>
        /// <returns></returns>
        public static Image SetByteToImage(byte[] imagebyte)
        {
            Image image;
            MemoryStream imagememorystream = new MemoryStream(imagebyte, 0, imagebyte.Length);
            image = Image.FromStream(imagememorystream);
            return image;
        }