public interface IFileHelper

    {

        /// <summary>

        /// 保存文件 (返回 Test.jpg) 出错就返回 error|错误信息

        /// </summary>

        string SaveFile(IFormFile file, FileCategory fc);

        bool DeleteFile(string fileName, FileCategory fc);

    }

public class FileHelper: IFileHelper

    {

        private readonly IHostingEnvironment _hostingEnv;

        private static readonly Random _rdm = new Random();

        public FileHelper(IHostingEnvironment env)

        {

            _hostingEnv = env;

        }

        /// <summary>

        /// 保存文件(返回新文件名)

        /// </summary>

        /// <param name="file"></param>

        /// <param name="fc"></param>

        /// <returns></returns>

        public string SaveFile(IFormFile file, FileCategory fc)

        {

            var path = GetUploadPath(fc);

            var targetDirectory = Path.Combine(_hostingEnv.WebRootPath, string.Format(path));

            //这里进行随机文件名

            var fileName = GetRandName(file);

            var savePath = Path.Combine(targetDirectory, fileName);

            try

            {

                file.CopyTo(new FileStream(savePath, FileMode.Create));

                //return   Upload/NewsPhoto/Test.jpg

                //返回文件名

                return fileName;

            }

            catch

            {

                return "false";

            }

        }

        /// <summary>

        /// 删除文件

        /// </summary>

        /// <param name="fullPath"></param>

        /// <returns></returns>

        public bool DeleteFile(string fileName, FileCategory fc)

        {

            var path = GetUploadPath(fc);

            var targetDirectory = Path.Combine(_hostingEnv.WebRootPath, string.Format(path));

            //物理完整路径

            var physicalPath = Path.Combine(targetDirectory, fileName);

            try

            {

                File.Delete(physicalPath);

                return true;

            }

            catch

            {

                return false;

            }

        }

        /// <summary>

        /// 相对路径 /Upload/NewsPhoto/Test.jpg

        /// </summary>

        /// <param name="path"></param>

        /// <returns></returns>

        public static string GetFullPath(FileCategory fc,string fileName)

        {

            var path = GetUploadPath(fc);

            return Path.Combine(string.Format(path), fileName);

        }

        /// <summary>

        /// 获取到上传路径（Upload//CasePhoto//）

        /// </summary>

        /// <param name="fc"></param>

        /// <returns></returns>

        public static  string GetUploadPath(FileCategory fc)

        {

            switch (fc)

            {

                case FileCategory.CasePhoto:return "Upload//CasePhoto//";

                case FileCategory.NewsPhoto:return "Upload//NewsPhoto//";

                case FileCategory.CompanyPhoto: return "Upload//CompanyPhoto//";

                case FileCategory.PositionPhoto: return "Upload//PositionPhoto//";

                case FileCategory.Partner: return "Upload//Partner//";

                default:return "";

            }

        }

        public static string GetRandName(string oldFileName)

        {

            //获取后缀

            var extension= GetExtensionWithDot(oldFileName);

            //产生新的文件名

            var newFileName = DateTime.Now.ToFileTime().ToString() + _rdm.Next();

            //组合

            return newFileName + extension;

        }

        public static string GetRandName(IFormFile file)

        {

            var fileName = file.FileName;

            var randName = GetRandName(fileName);

            return randName;

        }

        public enum FileCategory

        {

            /// <summary>

            /// 案例文章插图

            /// </summary>

            CasePhoto,

            /// <summary>

            /// 新闻文章插图

            /// </summary>

            NewsPhoto,

            /// <summary>

            /// 公司介绍插图

            /// </summary>

            CompanyPhoto,

            /// <summary>

            /// 职位描述插图

            /// </summary>

            PositionPhoto,

            /// <summary>

            /// 合作伙伴

            /// </summary>

            Partner,

        }

        /// <summary>

        /// 获取到后缀名的方法

        /// </summary>

        public static string GetExtensionWithDot(string fileName)

        {

            var dotIndex = fileName.LastIndexOf('.');

            if (dotIndex <  || dotIndex >= fileName.Length) return string.Empty;

            return fileName.Substring(dotIndex);

        }
}

public void ConfigureServices(IServiceCollection services)

{

　　　　services.AddSingleton<IFileHelper, FileHelper>();

}

public class UploadController : Controller

    {

        private readonly IFileHelper _fileHelper;

        public UploadController(IFileHelper fileHelper)

        {

            _fileHelper = fileHelper;

        }

        /// <summary>

        /// 专门为Case的文件上传 有可能有两个name 不支持H5 wangEditorFormFile  支持h5 wangEditorH5File

        /// </summary>

        /// <returns></returns>

        [HttpPost]

        public string UploadCompanyPhoto(IFormFile wangEditorFormFile = null, IFormFile wangEditorH5File = null)

        {

            //全部用/，windows支持/

            return Upload(FileCategory.CompanyPhoto, wangEditorFormFile, wangEditorH5File);

        }

        private string Upload(FileCategory fc ,IFormFile wangEditorFormFile = null, IFormFile wangEditorH5File = null)

        {

            if (wangEditorFormFile == null && wangEditorH5File == null)

            {

                return "error|无文件上传";

            }

            var file = wangEditorFormFile == null ? wangEditorH5File : wangEditorFormFile;

            var result = _fileHelper.SaveFile(file, fc);

            //判断是否错误

            if (result == "false")

            {

                return "error|上传失败";

            }

            else

            {

                return "http://" + Request.Host.ToString() + "/" + FileHelper.GetFullPath(fc, result); ;

            }

        }

    }