一、.Net Core 分块上传文件
一、前端实现
@*
For more information on enabling MVC for empty projects, visit http://go.microsoft.com/fwlink/?LinkID=397860
*@
@{
ViewData["Title"] = "Index";
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
<link href="https://cdn.bootcss.com/webuploader/0.1.1/webuploader.css" rel="stylesheet">
<link href="https://cdn.bootcss.com/twitter-bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
<script type="text/javascript">
var UploadPath = "";
//开始上传
function UploadStart() {
var file = $("#path")[0].files[0];
AjaxFile(file, 0);
}
function AjaxFile(file, i) {
var name = file.name, //文件名
size = file.size, //总大小shardSize = 2 * 1024 * 1024,
shardSize = 2 * 1024 * 1024,//以2MB为一个分片
shardCount = Math.ceil(size / shardSize); //总片数
if (i >= shardCount) {
return;
}
//计算每一片的起始与结束位置
var start = i * shardSize,
end = Math.min(size, start + shardSize);
//构造一个表单，FormData是HTML5新增的
var form = new FormData();
form.append("data", file.slice(start, end)); //slice方法用于切出文件的一部分
form.append("lastModified", file.lastModified);
form.append("fileName", name);
form.append("total", shardCount); //总片数
form.append("index", i + 1); //当前是第几片
UploadPath = file.lastModified
//Ajax提交文件
$.ajax({
url: "/Upload/UploadFile",
type: "POST",
data: form,
async: true, //异步
processData: false, //很重要，告诉jquery不要对form进行处理
contentType: false, //很重要，指定为false才能形成正确的Content-Type
success: function (result) {
if (result != null) {
i = result.number++;
var num = Math.ceil(i * 100 / shardCount);
$("#output").text(num + '%');
AjaxFile(file, i);
if (result.mergeOk) {
var filepath = $("#path");
filepath.after(filepath.clone().val(""));
filepath.remove();//清空input file
$('#upfile').val('请选择文件');
alert("success!!!");
}
}
}
});
}
</script>
</head>
<body>
<div class="row" style="margin-top:20%">
<div class="col-lg-4"></div>
<div class="col-lg-4">
<input type="text" value="请选择文件" size="20" name="upfile" id="upfile" style="border:1px dotted #ccc">
<input type="button" value="浏览" onclick="path.click()" style="border:1px solid #ccc;background:#fff">
<input type="file" id="path" style="display:none" multiple="multiple" onchange="upfile.value=this.value">
<br />
<span id="output">0%</span>
<button type="button" id="file" onclick="UploadStart()" style="border:1px solid #ccc;background:#fff">开始上传</button>
</div>
<div class="col-lg-4"></div>
</div>
</body>
</html>
这里的主要思路是利用html5 File api的slice方法把文件分块，
然后new一个FormData()对象用于储存文件数据，之后就是递归调用AjaxFile方法直至上传完毕。
后台代码:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
namespace WebApplication2.Controllers
{
public class UploadController : Controller
{
public IActionResult Index()
{
return View();
}
[HttpPost]
public async Task<ActionResult> UploadFile()
{
var data = Request.Form.Files["data"];
string lastModified = Request.Form["lastModified"].ToString();
var total = Request.Form["total"];
var fileName = Request.Form["fileName"];
var index = Request.Form["index"];
string temporary = Path.Combine(@"D:浏览器", lastModified);//临时保存分块的目录
try
{
if (!Directory.Exists(temporary))
Directory.CreateDirectory(temporary);
string filePath = Path.Combine(temporary, index.ToString());
if (!Convert.IsDBNull(data))
{
await Task.Run(() => {
FileStream fs = new FileStream(filePath, FileMode.Create);
data.CopyTo(fs);
fs.Close();
});
}
bool mergeOk = false;
if (total == index)
{
mergeOk = await FileMerge(lastModified, fileName);
}
Dictionary<string, object> result = new Dictionary<string, object>();
result.Add("number", index);
result.Add("mergeOk", mergeOk);
return Json(result);
}
catch (Exception ex)
{
Directory.Delete(temporary);//删除文件夹
throw ex;
}
}
public async Task<bool> FileMerge(string lastModified, string fileName)
{
bool ok = false;
try
{
var temporary = Path.Combine(@"D:浏览器", lastModified);//临时文件夹
fileName = Request.Form["fileName"];//文件名
string fileExt = Path.GetExtension(fileName);//获取文件后缀
var files = Directory.GetFiles(temporary);//获得下面的所有文件
var finalPath = Path.Combine(@"D:浏览器", DateTime.Now.ToString("yyMMddHHmmss") + fileExt);//最终的文件名（demo中保存的是它上传时候的文件名，实际操作肯定不能这样）
var fs = new FileStream(finalPath, FileMode.Create);
foreach (var part in files.OrderBy(x => x.Length).ThenBy(x => x))//排一下序，保证从0-N Write
{
var bytes = System.IO.File.ReadAllBytes(part);
await fs.WriteAsync(bytes, 0, bytes.Length);
bytes = null;
System.IO.File.Delete(part);//删除分块
}
fs.Close();
Directory.Delete(temporary);//删除文件夹
ok = true;
}
catch (Exception ex)
{
throw ex;
}
return ok;
}
}
}
这里的思路就是先保存每一个分块的文件到一个临时文件夹，
最后再通过FileStream合并这些临时文件（合并时必需要按顺序）。
后台的方法都进行了异步化（async await真的非常好用），
虽然不知道对效率有没有提升，但是就是觉得这样很酷。