从零讲解.Net Core开发实现图片文件上传下载

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")    });   }   }  }

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

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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