ASP.NET Core Upload Multiple Files Simple Tutorial

2019年12月9日 3518点热度 2人点赞 2条评论

内容目录

Example source code download link

https://qcloud.coding.net/api/project/3915794/files/4463836/download

Project address: https://dev.tencent.com/u/whuanle/p/asp.netcore_file_upload/attachment

Create Application

Open VS 2017

　　--Create a new ASP.NET Core web application

　　　　--Web Application (Model-View-Controller)

Application name and path can be default

Remove Unnecessary Content

Open HomeController.cs file and delete all methods

Open Views/Home directory and delete all files

Create a new file directory in the application

Start Programming

Now, let's write the program to implement file upload

Step one File upload interface

Create a new method in HomeController

This action is the interface for uploading files

        public IActionResult Upload()
        {
            return View();
        }

Then add a view Upload.cshtml in the Views/Home directory

Copy the following code into Upload.cshtml

This part is a file upload form, and there is nothing special about it, so no explanation of the code's function will be provided here.

。

@{
    ViewData["Title"] = "Upload";
}
<form method="post" enctype="multipart/form-data" asp-controller="Home" asp-action="UploadFiles">
<div class="form-group">
<div class="col-md-12">
<p>Select the files to upload</p>
<input type="file" name="files" multiple />
</div>
</div>
<div class="form-group">
<div class="col-md-12">
<input type="submit" value="Upload" />
</div>
</div>
</form>

Annex

Step Two: File Upload Functionality

Open HomeController

The references at the top are as follows:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

Add a method inside the HomeController class

 　　　　 [HttpPost]　　　　// Uploading files is a post method, can add or omit here
        public async Task<IActionResult> UploadFiles(List<IFormFile> files)
        {
            long size = files.Sum(f => f.Length);       // Calculate the total size of all files
        <span style="color: #0000ff;">var</span> filepath = Directory.GetCurrentDirectory() + <span style="color: #800000;">"</span><span style="color: #800000;">\\file</span><span style="color: #800000;">"</span>;  <span style="color: #008000;">//</span><span style="color: #008000;"> Path to store files</span>
        ViewBag.log = <span style="color: #800000;">"</span><span style="color: #800000;">Log content is:</span><span style="color: #800000;">"</span>;     <span style="color: #008000;">//</span><span style="color: #008000;"> Record log content</span>

        <span style="color: #0000ff;">foreach</span> (<span style="color: #0000ff;">var</span> item <span style="color: #0000ff;">in</span> files)     <span style="color: #008000;">//</span><span style="color: #008000;"> Upload the selected file list</span>

            {

if (item.Length > 0)        // Only upload files larger than size 0

                {

var thispath = filepath + "\" + item.FileName;     // The current upload file should be stored here
                <span style="color: #0000ff;">if</span> (System.IO.File.Exists(thispath) == <span style="color: #0000ff;">true</span>)        <span style="color: #008000;">//</span><span style="color: #008000;"> If the file already exists, skip uploading this file</span>

                    {

ViewBag.log += "\r\nFile already exists：" + thispath.ToString();

continue;

}
                </span><span style="color: #008000;">//</span><span style="color: #008000;"> Upload file</span>
                <span style="color: #0000ff;">using</span> (<span style="color: #0000ff;">var</span> stream = <span style="color: #0000ff;">new</span> FileStream(thispath, FileMode.Create))      <span style="color: #008000;">//</span><span style="color: #008000;"> Create a file stream with a specific name</span>

                    {

try

{

await item.CopyToAsync(stream);     // Upload file

                        }

catch (Exception ex)        // Exception handling during upload

                        {

ViewBag.log += "\r\n" + ex.ToString();

}

}

}

}

return View();

}


Note: The usage of IFormFile will be introduced later

Here’s a structural diagram

Create a new view UploadFiles.cshtml in the Views/Home directory

Open UploadFiles.cshtml

Put the following code into it

The code below outputs the files in the file directory and displays the log record

@using System.IO
@{
    ViewData["Title"] = "UploadFiles";
}
<h2>Directory Content</h2>
<ul class="list-group">　　// Razor syntax to output files in the file directory 
@{
var items = Directory.GetFiles(Directory.GetCurrentDirectory() + "\file");
foreach (var item in items)
{
<li class="list-group-item">@item.ToString()</li>
}
}
</ul>
<hr />
<h2>Log Content</h2>
<p>
@ViewBag.log
</p>

Run

Press F5 to run the application

Open

https://localhost:your_port/Home/Upload

to see the running interface

Please select smaller document files such as txt, doc, pdf, images, etc. for testing; do not upload too many files

Do not choose too many or large files, dll files, executable files, etc. as it may cause errors

Upload Success

After a successful upload, you will be redirected to 　　https://localhost:your_port/Home/UploadFiles

Additional Notes

When uploading a duplicate file, the interface will prompt

Uploading files that are too large or too many will result in an error

Usage of IFormFile

The namespace is Microsoft.AspNetCore.Http

Properties

ContentDisposition	Gets the raw Content-Disposition header of the uploaded file.
ContentType	Gets the raw Content-Type header of the uploaded file.
FileName	Gets the file name from the Content-Disposition header.
Headers	Gets the header dictionary of the uploaded file.
Length	Gets the length of the file in bytes.
Name	Gets the form field name from the Content-Disposition header.

Methods

CopyTo(Stream)	Copies the content of the uploaded file to the`target` stream.
CopyToAsync(Stream, CancellationToken)	Asynchronously copies the content of the uploaded file to the`target` stream.
OpenReadStream()	Opens a request stream to read the uploaded file.