小编给大家分享一下.Net Core如何实现图片文件上传下载功能，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
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>
<h3>article-form</h3>
</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！
以上是“.Net Core如何实现图片文件上传下载功能”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注亿速云行业资讯频道！
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