public static IHostBuilder CreateHostBuilder(string[] args) =>
  Host.CreateDefaultBuilder(args)
    .ConfigureKestrel((context, options) =>
    {
      // Handle requests up to 50 MB
      options.Limits.MaxRequestBodySize = 52428800;
    })
    .ConfigureWebHostDefaults(webBuilder =>
    {
      webBuilder.UseStartup<Startup>();
    });

<system.webServer>
 <security>
  <requestFiltering>
   <!-- Handle requests up to 50 MB -->
   <requestLimits maxAllowedContentLength="52428800" />
  </requestFiltering>
 </security>
</system.webServer>

using System;
using System.IO;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;

namespace FileUploadManage.Controllers
{
  /// <summary>
  /// 圖片，視頻，音頻，文檔等相關(guān)文件通用上傳服務(wù)類
  /// </summary>
  public class FileUploadController : Controller
  {
    private static IHostingEnvironment _hostingEnvironment;

    public FileUploadController(IHostingEnvironment hostingEnvironment)
    {
      _hostingEnvironment = hostingEnvironment;
    }

    /// <summary>
    /// 單文件上傳
    /// </summary>
    /// <returns></returns>
    public JsonResult SingleFileUpload()
    {
      var formFile = Request.Form.Files[0];//獲取請(qǐng)求發(fā)送過(guò)來(lái)的文件
      var currentDate = DateTime.Now;
      var webRootPath = _hostingEnvironment.WebRootPath;//>>>相當(dāng)于HttpContext.Current.Server.MapPath("") 

      try
      {
        var filePath = $"/UploadFile/{currentDate:yyyyMMdd}/";

        //創(chuàng)建每日存儲(chǔ)文件夾
        if (!Directory.Exists(webRootPath + filePath))
        {
          Directory.CreateDirectory(webRootPath + filePath);
        }

        if (formFile != null)
        {
          //文件后綴
          var fileExtension = Path.GetExtension(formFile.FileName);//獲取文件格式，拓展名

          //判斷文件大小
          var fileSize = formFile.Length;

          if (fileSize > 1024 * 1024 * 10) //10M TODO:(1mb=1024X1024b)
          {
            return new JsonResult(new { isSuccess = false, resultMsg = "上傳的文件不能大于10M" });
          }

          //保存的文件名稱(以名稱和保存時(shí)間命名)
          var saveName = formFile.FileName.Substring(0, formFile.FileName.LastIndexOf('.'))+"_"+currentDate.ToString("HHmmss")+ fileExtension;

          //文件保存
          using (var fs = System.IO.File.Create(webRootPath + filePath + saveName))
          {
            formFile.CopyTo(fs);
            fs.Flush();
          }

          //完整的文件路徑
          var completeFilePath = Path.Combine(filePath, saveName);

          return new JsonResult(new { isSuccess = true, returnMsg = "上傳成功", completeFilePath = completeFilePath });
        }
        else
        {
          return new JsonResult(new { isSuccess = false, resultMsg = "上傳失敗，未檢測(cè)上傳的文件信息~" });
        }

      }
      catch (Exception ex)
      {
        return new JsonResult(new { isSuccess = false, resultMsg = "文件保存失敗，異常信息為：" + ex.Message });
      }
    }

  }
}

using System;
using System.Collections.Generic;
using System.IO;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Internal;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore.Internal;

namespace FileUploadManage.Controllers
{
  /// <summary>
  /// 圖片，視頻，音頻，文檔等相關(guān)文件通用上傳服務(wù)類
  /// </summary>
  public class FileUploadController : Controller
  {
    private static IHostingEnvironment _hostingEnvironment;

    public FileUploadController(IHostingEnvironment hostingEnvironment)
    {
      _hostingEnvironment = hostingEnvironment;
    }

    /// <summary>
    /// 多文件上傳
    /// </summary>
    /// <param name="formCollection">表單集合值</param>
    /// <returns>服務(wù)器存儲(chǔ)的文件信息</returns>

    public JsonResult MultiFileUpload(IFormCollection formCollection)
    {
      var currentDate = DateTime.Now;
      var webRootPath = _hostingEnvironment.WebRootPath;//>>>相當(dāng)于HttpContext.Current.Server.MapPath("") 
      var uploadFileRequestList = new List<UploadFileRequest>();
      try
      {
        //FormCollection轉(zhuǎn)化為FormFileCollection
        var files = (FormFileCollection)formCollection.Files;

        if (files.Any())
        {
          foreach (var file in files)
          {
            var uploadFileRequest = new UploadFileRequest();

            var filePath = $"/UploadFile/{currentDate:yyyyMMdd}/";

            //創(chuàng)建每日存儲(chǔ)文件夾
            if (!Directory.Exists(webRootPath + filePath))
            {
              Directory.CreateDirectory(webRootPath + filePath);
            }

            //文件后綴
            var fileExtension = Path.GetExtension(file.FileName);//獲取文件格式，拓展名

            //判斷文件大小
            var fileSize = file.Length;

            if (fileSize > 1024 * 1024 * 10) //10M TODO:(1mb=1024X1024b)
            {
              continue;
            }

            //保存的文件名稱(以名稱和保存時(shí)間命名)
            var saveName = file.FileName.Substring(0, file.FileName.LastIndexOf('.')) + "_" + currentDate.ToString("HHmmss") + fileExtension;

            //文件保存
            using (var fs = System.IO.File.Create(webRootPath + filePath + saveName))
            {
              file.CopyTo(fs);
              fs.Flush();
            }

            //完整的文件路徑
            var completeFilePath = Path.Combine(filePath, saveName);

            uploadFileRequestList.Add(new UploadFileRequest()
            {
              FileName = saveName,
              FilePath = completeFilePath
            });
          }
        }
        else
        {
          return new JsonResult(new { isSuccess = false, resultMsg = "上傳失敗，未檢測(cè)上傳的文件信息~" });
        }
      }
      catch (Exception ex)
      {
        return new JsonResult(new { isSuccess = false, resultMsg = "文件保存失敗，異常信息為：" + ex.Message });
      }

      if (uploadFileRequestList.Any())
      {
        return new JsonResult(new { isSuccess = true, returnMsg = "上傳成功", filePathArray = uploadFileRequestList });
      }
      else
      {
        return new JsonResult(new { isSuccess = false, resultMsg = "網(wǎng)絡(luò)打瞌睡了，文件保存失敗" });
      }
    }

  }

  /// <summary>
  /// 對(duì)文件上傳響應(yīng)模型
  /// </summary>
  public class UploadFileRequest
  {
    /// <summary>
    /// 文件名稱
    /// </summary>
    public string FileName { get; set; }

    /// <summary>
    /// 文件路徑
    /// </summary>
    public string FilePath { get; set; }
  }
}