从零讲解.Net Core开发实现图片文件上传下载

这篇文章主要为大家详细介绍了.Net Core实现图片文件上传下载功能，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

当下.Net Core项目可是如雨后春笋一般发展起来，作为.Net大军中的一员，我热忱地拥抱了.Net Core并且积极使用其进行业务的开发，我们先介绍下.Net Core项目下实现文件上传下载接口。

一、开发环境

毋庸置疑，宇宙第一IDE VisualStudio 2017

二、项目结构

FilesController 文件上传下载控制器

PictureController 图片上传下载控制器

Return_Helper_DG 返回值帮助类

三、关键代码

1、首先我们来看Startup.cs 这个是我们的程序启动配置类，在这里我们进行一系列的配置。

跨域配置：

当然跨域少不了dll的引用，我们使用Nuget引用相关的引用包

服务器资源路径置换，这样可以防止客户端猜测服务端文件路径，制造一个虚拟的隐射进行访问，提高了安全性。

Startup.cs的完整代码如下：

using Microsoft.AspNetCore.Builder;using Microsoft.AspNetCore.Hosting;using Microsoft.AspNetCore.Http;using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;using Microsoft.Extensions.FileProviders;using Microsoft.Extensions.Logging;using System.IO;namespace QX_Core.FilesCenter{ public class Startup { public Startup(IHostingEnvironment env) {  var builder = new ConfigurationBuilder()  .SetBasePath(env.ContentRootPath)  .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)  .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)  .AddEnvironmentVariables();  Configuration = builder.Build(); } public IConfigurationRoot Configuration { get; } // This method gets called by the runtime. Use this method to add services to the container. public void ConfigureServices(IServiceCollection services) {  // Add framework services.  services.AddMvc();  #region CORS  services.AddCors(options =>  {  options.AddPolicy("AllowSpecificOrigin",   builder => builder.WithOrigins("http://localhost:3997").AllowAnyHeader().AllowAnyOrigin().AllowAnyMethod());  });  #endregion } // This method gets called by the runtime. Use this method to configure the HTTP request pipeline. public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) {  //loggerFactory.AddConsole(Configuration.GetSection("Logging"));  //loggerFactory.AddDebug();  app.UseMvc();  // Shows UseCors with named policy.  app.UseCors("AllowSpecificOrigin");  app.UseStaticFiles(new StaticFileOptions()  {  FileProvider = new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot/Files")),  RequestPath = new PathString("/src")  }); } }}

2、Return_Helper_DG类用户设置一个统一的返回值反馈到客户端
Return_Helper_DG类的代码如下：

using System.Net;/*** author:qixiao* create:2017-5-19 15:15:05* */namespace QX_Core.FilesCenter.QX_Core.Helper{ public abstract class Return_Helper_DG { public static object IsSuccess_Msg_Data_HttpCode(bool isSuccess, string msg, dynamic data, HttpStatusCode httpCode = HttpStatusCode.OK) {  return new { isSuccess = isSuccess, msg = msg, httpCode = httpCode, data = data }; } public static object Success_Msg_Data_DCount_HttpCode(string msg, dynamic data = null, int dataCount = 0, HttpStatusCode httpCode = HttpStatusCode.OK) {  return new { isSuccess = true, msg = msg, httpCode = httpCode, data = data, dataCount = dataCount }; } public static object Error_Msg_Ecode_Elevel_HttpCode(string msg, int errorCode = 0, int errorLevel = 0, HttpStatusCode httpCode = HttpStatusCode.InternalServerError) {  return new { isSuccess = false, msg = msg, httpCode = httpCode, errorCode = errorCode, errorLevel = errorLevel }; } }}

3、FilesController是我们的文件上传控制器接口，这里定义了对上传的文件的接收操作，并且在控制器上启用跨域配置

using Microsoft.AspNetCore.Cors;using Microsoft.AspNetCore.Hosting;using Microsoft.AspNetCore.Mvc;using Microsoft.Net.Http.Headers;using QX_Core.FilesCenter.QX_Core.Helper;using System;using System.Collections.Generic;using System.IO;using System.Linq;namespace QX_Core.FilesCenter.Controllers{ //[Produces("application/json")] [Route("api/[controller]")] [EnableCors("AllowSpecificOrigin")] public class FilesController : Controller { private IHostingEnvironment hostingEnv; public FilesController(IHostingEnvironment env) {  this.hostingEnv = env; } [HttpPost] public IActionResult Post() {  var files = Request.Form.Files;  long size = files.Sum(f => f.Length);  //size > 100MB refuse upload !  if (size > 104857600)  {  return Json(Return_Helper_DG.Error_Msg_Ecode_Elevel_HttpCode("files total size > 100MB , server refused !"));  }  List<string> filePathResultList = new List<string>();  foreach (var file in files)  {  var fileName = ContentDispositionHeaderValue.Parse(file.ContentDisposition).FileName.Trim('"');  string filePath = hostingEnv.WebRootPath + $@"\Files\Files\";  if (!Directory.Exists(filePath))  {   Directory.CreateDirectory(filePath);  }  fileName = Guid.NewGuid() + "." + fileName.Split('.')[1];  string fileFullName = filePath + fileName;  using (FileStream fs = System.IO.File.Create(fileFullName))  {   file.CopyTo(fs);   fs.Flush();  }  filePathResultList.Add($"/src/Files/{fileName}");  }  string message = $"{files.Count} file(s) /{size} bytes uploaded successfully!";  return Json(Return_Helper_DG.Success_Msg_Data_DCount_HttpCode(message, filePathResultList, filePathResultList.Count)); } }}

在上述的代码中，我们对上传的文件的大小进行了限制，并且对文件的大小进行反馈。

4、PictureController 图片上传控制器接口，类似于文件，不过对上传的图片类型进行了校验和限制

using Microsoft.AspNetCore.Cors;using Microsoft.AspNetCore.Hosting;using Microsoft.AspNetCore.Mvc;using Microsoft.Net.Http.Headers;using QX_Core.FilesCenter.QX_Core.Helper;using System;using System.Collections.Generic;using System.IO;using System.Linq;namespace QX_Core.FilesCenter.Controllers{ //[Produces("application/json")] [Route("api/[controller]")] [EnableCors("AllowSpecificOrigin")] public class PicturesController : Controller { private IHostingEnvironment hostingEnv; string[] pictureFormatArray = { "png", "jpg", "jpeg", "bmp", "gif","ico", "PNG", "JPG", "JPEG", "BMP", "GIF","ICO" }; public PicturesController(IHostingEnvironment env) {  this.hostingEnv = env; } [HttpPost] public IActionResult Post() {  var files = Request.Form.Files;  long size = files.Sum(f => f.Length);  //size > 100MB refuse upload !  if (size > 104857600)  {  return Json(Return_Helper_DG.Error_Msg_Ecode_Elevel_HttpCode("pictures total size > 100MB , server refused !"));  }  List<string> filePathResultList = new List<string>();  foreach (var file in files)  {  var fileName = ContentDispositionHeaderValue.Parse(file.ContentDisposition).FileName.Trim('"');  string filePath = hostingEnv.WebRootPath + $@"\Files\Pictures\";  if (!Directory.Exists(filePath))  {   Directory.CreateDirectory(filePath);  }  string suffix = fileName.Split('.')[1];  if (!pictureFormatArray.Contains(suffix))  {   return Json(Return_Helper_DG.Error_Msg_Ecode_Elevel_HttpCode("the picture format not support ! you must upload files that suffix like 'png','jpg','jpeg','bmp','gif','ico'."));  }  fileName = Guid.NewGuid() + "." + suffix;  string fileFullName = filePath + fileName;  using (FileStream fs = System.IO.File.Create(fileFullName))  {   file.CopyTo(fs);   fs.Flush();  }  filePathResultList.Add($"/src/Pictures/{fileName}");  }  string message = $"{files.Count} file(s) /{size} bytes uploaded successfully!";  return Json(Return_Helper_DG.Success_Msg_Data_DCount_HttpCode(message, filePathResultList, filePathResultList.Count)); } }}

到此，我们的文件图片上传代码已经全部完成，下面我们对文件上传的客户端进行实现

四、客户端的实现

客户端我们很简单地用jQuery Ajax的方式进行图片文件的提交，客户端代码的实现：

<!doctype><head> <script src="jquery-3.2.0.min.js"></script> <script> $(document).ready(function () {  var appDomain = "http://localhost:53972/";  $("#btn_fileUpload").click(function () {    var fileUpload = $("#files").get(0);  var files = fileUpload.files;  var data = new FormData();  for (var i = 0; i < files.length; i++) {   data.append(files[i].name, files[i]);  }  $.ajax({   type: "POST",   url: appDomain+'api/Pictures',   contentType: false,   processData: false,   data: data,   success: function (data) {   console.log(JSON.stringify(data));   },   error: function () {   console.log(JSON.stringify(data));   }  });  });  //end click }) </script></head><title></title><body> <article> <header>  <h2>article-form</h2> </header> <p>  <form id="uploadForm" enctype="multipart/form-data">  <input type="file" id="files" name="files" placeholder="file" multiple>file-multiple属性可以选择多项<br><br>  <input type="button" id="btn_fileUpload" value="fileUpload">  </form> </p> </article></body>

五、代码测试

1.启动服务器