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 filePathResultList = new List(); 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 filePathResultList = new List(); 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：
article-form
五、代码测试
1.启动服务器
我们可以看到一个控制台和一个web自动启动，并且web显示默认的Values控制器的请求返回值。
2.图片上传
我们使用ajax的方式进行图片的上传操作，打开测试web页面，并且选择图片，点击上传，查看控制台返回的结果：
可以看到，一张图片上传成功！
输入返回的地址，我们可以看到成功访问到了图片，特别注意这里服务器路径的改变：
多图片上传：
可见，多图片上传没有任何问题！
同样进行文件上传的测试：
同样，文件上传也没有任何问题！
六、总结
至此，我们已经实现了预期的.Net Core图片文件上传的全部功能！
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