web api调用
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using YiSha.Util;
using YiSha.Util.Extension;
using YiSha.Util.Model;namespace YiSha.Admin.WebApi.Controllers
{[Route("[controller]/[action]")][ApiController][AuthorizeFilter]public class FileController : ControllerBase{#region 上传单个文件[HttpPost]public async Task<TData<string>> UploadFile(int fileModule, IFormCollection fileList){TData<string> obj = await FileHelper.UploadFile(fileModule, fileList.Files);return obj;}#endregion#region 删除单个文件[HttpPost]public TData<string> DeleteFile(int fileModule, string filePath){TData<string> obj = FileHelper.DeleteFile(fileModule, filePath);return obj;}#endregion#region 下载文件[HttpGet]public FileContentResult DownloadFile(string filePath, int delete = 1){TData<FileContentResult> obj = FileHelper.DownloadFile(filePath, delete);if (obj.Tag == 1){return obj.Data;}else{throw new Exception("下载失败：" + obj.Message);}}#endregion}
}

  实现help：

  public class FileHelper{#region 创建文本文件/// <summary>/// 创建文件/// </summary>/// <param name="path"></param>/// <param name="content"></param>public static void CreateFile(string path, string content){if (!Directory.Exists(Path.GetDirectoryName(path))){Directory.CreateDirectory(Path.GetDirectoryName(path));}using (StreamWriter sw = new StreamWriter(path, false, Encoding.UTF8)){sw.Write(content);}}#endregion#region 上传单个文件/// <summary>/// 上传单个文件/// </summary>/// <param name="fileModule"></param>/// <param name="fileCollection"></param>/// <returns></returns>public async static Task<TData<string>> UploadFile(int fileModule, IFormFileCollection files){string dirModule = string.Empty;TData<string> obj = new TData<string>();if (files == null || files.Count == 0){obj.Message = "请先选择文件！";return obj;}if (files.Count > 1){obj.Message = "一次只能上传一个文件！";return obj;}TData objCheck = null;IFormFile file = files[0];switch (fileModule){case (int)UploadFileType.Portrait:objCheck = CheckFileExtension(Path.GetExtension(file.FileName), ".jpg|.jpeg|.gif|.png");if (objCheck.Tag != 1){obj.Message = objCheck.Message;return obj;}dirModule = UploadFileType.Portrait.ToString();break;case (int)UploadFileType.News:if (file.Length > 5 * 1024 * 1024) // 5MB{obj.Message = "文件最大限制为 5MB";return obj;}objCheck = CheckFileExtension(Path.GetExtension(file.FileName), ".jpg|.jpeg|.gif|.png");if (objCheck.Tag != 1){obj.Message = objCheck.Message;return obj;}dirModule = UploadFileType.News.ToString();break;case (int)UploadFileType.Import:objCheck = CheckFileExtension(Path.GetExtension(file.FileName), ".xls|.xlsx");if (objCheck.Tag != 1){obj.Message = objCheck.Message;return obj;}dirModule = UploadFileType.Import.ToString();break;default:obj.Message = "请指定上传到的模块";return obj;}string fileExtension = TextHelper.GetCustomValue(Path.GetExtension(file.FileName), ".png");string newFileName = SecurityHelper.GetGuid(true) + fileExtension;string dir = "Resource" + Path.DirectorySeparatorChar + dirModule + Path.DirectorySeparatorChar + DateTime.Now.ToString("yyyy-MM-dd").Replace('-', Path.DirectorySeparatorChar) + Path.DirectorySeparatorChar;string absoluteDir = Path.Combine(GlobalContext.HostingEnvironment.ContentRootPath, dir);string absoluteFileName = string.Empty;if (!Directory.Exists(absoluteDir)){Directory.CreateDirectory(absoluteDir);}absoluteFileName = absoluteDir + newFileName;try{using (FileStream fs = File.Create(absoluteFileName)){await file.CopyToAsync(fs);fs.Flush();}obj.Data = Path.AltDirectorySeparatorChar + ConvertDirectoryToHttp(dir) + newFileName;obj.Message = Path.GetFileNameWithoutExtension(TextHelper.GetCustomValue(file.FileName, newFileName));obj.Description = (file.Length / 1024).ToString(); // KBobj.Tag = 1;}catch (Exception ex){obj.Message = ex.Message;}return obj;}#endregion#region 删除单个文件/// <summary>/// 删除单个文件/// </summary>/// <param name="fileModule"></param>/// <param name="filePath"></param>/// <returns></returns>public static TData<string> DeleteFile(int fileModule, string filePath){TData<string> obj = new TData<string>();string dirModule = fileModule.GetDescriptionByEnum<UploadFileType>();if (string.IsNullOrEmpty(filePath)){obj.Message = "请先选择文件！";return obj;}filePath = FilterFilePath(filePath);filePath = "Resource" + Path.DirectorySeparatorChar + dirModule + Path.DirectorySeparatorChar + filePath;string absoluteDir = Path.Combine(GlobalContext.HostingEnvironment.ContentRootPath, filePath);try{if (File.Exists(absoluteDir)){File.Delete(absoluteDir);}else{obj.Message = "文件不存在";}obj.Tag = 1;}catch (Exception ex){obj.Message = ex.Message;}return obj;}#endregion#region 下载文件/// <summary>/// 下载文件/// </summary>/// <param name="filePath"></param>/// <param name="delete"></param>/// <returns></returns>public static TData<FileContentResult> DownloadFile(string filePath, int delete){filePath = FilterFilePath(filePath);if (!filePath.StartsWith("wwwroot") && !filePath.StartsWith("Resource")){throw new Exception("非法访问");}TData<FileContentResult> obj = new TData<FileContentResult>();string absoluteFilePath = GlobalContext.HostingEnvironment.ContentRootPath + Path.DirectorySeparatorChar + filePath.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);byte[] fileBytes = File.ReadAllBytes(absoluteFilePath);if (delete == 1){File.Delete(absoluteFilePath);}// md5 值string fileNamePrefix = DateTime.Now.ToString("yyyyMMddHHmmss");string fileNameWithoutExtension = Path.GetFileNameWithoutExtension(filePath);string title = fileNameWithoutExtension;if (fileNameWithoutExtension.Contains("_")){title = fileNameWithoutExtension.Split('_')[1].Trim();}string fileExtensionName = Path.GetExtension(filePath);obj.Data = new FileContentResult(fileBytes, "application/octet-stream"){FileDownloadName = string.Format("{0}_{1}{2}", fileNamePrefix, title, fileExtensionName)};obj.Tag = 1;return obj;}#endregion #region GetContentTypepublic static string GetContentType(string path){var types = GetMimeTypes();var ext = Path.GetExtension(path).ToLowerInvariant();var contentType = types[ext];if (string.IsNullOrEmpty(contentType)){contentType = "application/octet-stream";}return contentType;}#endregion#region GetMimeTypespublic static Dictionary<string, string> GetMimeTypes(){return new Dictionary<string, string>{{".txt", "text/plain"},{".pdf", "application/pdf"},{".doc", "application/vnd.ms-word"},{".docx", "application/vnd.ms-word"},{".xls", "application/vnd.ms-excel"},{".xlsx", "application/vnd.openxmlformats officedocument.spreadsheetml.sheet"},{".png", "image/png"},{".jpg", "image/jpeg"},{".jpeg", "image/jpeg"},{".gif", "image/gif"},{".csv", "text/csv"}};}#endregionpublic static void CreateDirectory(string directory){if (!Directory.Exists(directory)){Directory.CreateDirectory(directory);}}public static void DeleteDirectory(string filePath){try{if (Directory.Exists(filePath)) //如果存在这个文件夹删除之 {foreach (string d in Directory.GetFileSystemEntries(filePath)){if (File.Exists(d))File.Delete(d); //直接删除其中的文件                        elseDeleteDirectory(d); //递归删除子文件夹 }Directory.Delete(filePath, true); //删除已空文件夹                 }}catch (Exception ex){LogHelper.Error(ex);}}public static string ConvertDirectoryToHttp(string directory){directory = directory.ParseToString();directory = directory.Replace(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);return directory;}public static string ConvertHttpToDirectory(string http){http = http.ParseToString();http = http.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);return http;}public static TData CheckFileExtension(string fileExtension, string allowExtension){TData obj = new TData();string[] allowArr = TextHelper.SplitToArray<string>(allowExtension.ToLower(), '|');if (allowArr.Where(p => p.Trim() == fileExtension.ParseToString().ToLower()).Any()){obj.Tag = 1;}else{obj.Message = "只有文件扩展名是 " + allowExtension + " 的文件才能上传";}return obj;}public static string FilterFilePath(string filePath){filePath = filePath.Replace("../", string.Empty);filePath = filePath.Replace("..", string.Empty);filePath = filePath.TrimStart('/');return filePath;}}