第一种通过 Form表单形式 （适用于 JS、Android、IOS等平台）

/// <summary>
        /// 上传文件
        /// </summary>
        /// <returns></returns>
        [HttpPost]
        public string PostFiles()
        {
            string result = "";
            HttpFileCollection filelist = HttpContext.Current.Request.Files;
            if (filelist != null && filelist.Count > 0)
            {
                for (int i = 0; i < filelist.Count; i++)
                {
                    HttpPostedFile file = filelist[i];
                    String Tpath =  "/" + DateTime.Now.ToString("yyyy-MM-dd") + "/";
                    string filename = file.FileName;
                    string FileName = DateTime.Now.ToString("yyyyMMddHHmmssfff") ;
                    string FilePath = 保存路径+ "\\" + Tpath + "\\";
                    DirectoryInfo di = new DirectoryInfo(FilePath);
                    if (!di.Exists) { di.Create(); }
                    try
                    {
                        file.SaveAs(FilePath + FileName);
                        result.obj =(Tpath + FileName).Replace("\\", "/");
                    }
                    catch (Exception ex)
                    {
                        result= "上传文件写入失败：" + ex.Message;
                    }
                }
            }
            else
            {
                result = "上传的文件信息不存在！";
            }
            
            return result;
        }

第二种，二进制上传

  /// <summary>
        /// 文件上传
        /// </summary>
        /// <param name="filename">文件名称</param>
        /// <param name="FileContent">文件内容</param>
        /// <returns></returns>
        [HttpPost]
        public string PostFile([FromUri]string filename, [FromBody] byte[] FileContent)
        {
            string result = "";
            if (FileContent != null)
            {
                String Tpath =  "/" + DateTime.Now.ToString("yyyy-MM-dd") + "/";
                string FilePath = 保存路径 + "\\" + Tpath+"\\";
                String Err = "";
                string FileName = DateTime.Now.ToString("yyyyMMddHHmmssfff");
                bool upres = FileUtil.WriteFile(FilePath, FileContent, FileName, out Err);
                if (upres)
                {
                    result= (Tpath + FileName).Replace("\\", "/");
                }
                else
                {
                    result= "上传文件写入失败：" + Err;
                }
            }
            else
            {
                result= "上传的文件信息不存在！";
            }
            return result;
        }

二进制保存到文件的方法

/// <summary>
        /// 二进制流写入文件
        /// </summary>
        /// <param name="filepath">文件路径</param>
        /// <param name="filecontent">文件内容</param>
        /// <param name="FileName">文件名</param>
        /// <param name="Errmsg">错误消息</param>
        /// <returns></returns>
        public static bool WriteFile(string filepath, byte[] filecontent, string FileName,out string Errmsg)
        {
            DirectoryInfo di = new DirectoryInfo(filepath);
            if (!di.Exists)
            {
                di.Create();
            }
            FileStream fstream = null;
            try
            {
                fstream = File.Create(filepath + "\\" + FileName, filecontent.Length);
 
                fstream.Write(filecontent, 0, filecontent.Length);   //二进制转换成文件
            }
            catch (Exception ex)
            {
                Errmsg = ex.Message;
                //抛出异常信息
                return false;
            }
            finally
            {
                if(fstream!=null)
                fstream.Close();
            }
            Errmsg = "";
            return true;
        }