html客户端部分：
<form action="upload.ashx" method="post" enctype="multipart/form-data"> 选择文件:<input type="file" name="file1" /><br /> <input type="submit" value="上传" /> </form>
一般处理程序服务器端：public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; HttpPostedFile file1 = context.Request.Files["file1"]; helper.uploadFile(file1, "~/upload/");//这里就是对相应方法进行调用 context.Response.Write("ok");//提示执行成功 }
上传代码的封装：注明：既然有了表单上传为什么又要ajax上传呢？因为表单上传过程中，整个页面就刷新了！ajax异步上传就可以达到只刷新局部位置，下面就简单看看ajax上传吧！
html客户端部分：
<html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <h2>文件上传</h2> <form action="/api/upload" method="post" enctype="multipart/form-data"> <input type="file" id="file1" /><br /> <input type="button" value="submit" id="submit-button" /> </form> </body> <script src="/static/libs/jquery/jquery-1.11.2.min.js"></script> <script> $("#submit-button").click(function (e) { e.preventDefault(); var formData = new FormData(); formData.append("pic-upload", document.getElementById("file1").files[0]); $.ajax({ type: ‘POST‘, url: "/api/upload", data: formData, //必须false才会自动加上正确的Content-Type contentType: false, // 必须false才会避开jQuery对 formdata 的默认处理，XMLHttpRequest会对 formdata 进行正确的处理 processData: false, success: function (response) { console.log(response); }, error: function (response) { console.log(response); } }); }) </script> </html>
node.js服务器端：const express = require("express")
const fs = require("fs")
const mysql = require("mysql")
const util = require("util")
const { getNow } = require("./tool")
const app = express();
var multer = require(‘multer‘);//获得中间件
var upload = multer({dest:‘uploads/‘});//指定配置项，这里指定文件保存于当前目录下的upload子目录
app.use(upload.single(‘pic-upload‘));//运用中间件，并且指明文件名,此名需要同html input name的文件名一致，否则会报错
const bodyParser = require("body-parser");
const { nextTick } = require("process");
app.use("/static/", express.static("./static/"));
app.use(‘/node_modules/‘, express.static(‘./node_modules/‘));
app.engine("html", require("express-art-template"))
app.use(bodyParser.urlencoded({ extended: false }))
app.use(bodyParser.json())
app.get("/upload", (req, res) => {
res.render("upload.html");
})
app.post("/api/upload", (req, res) => {
// 没有附带文件
res.send(req.file); //服务端响应把客户端获得的文件信息显示在客户端
})
app.get("/404", (req, res) => {
res.render("404.html");
})
// 配置一个全局错误处理中间件
app.use(function (err, req, res, next) {
res.status(500).json({
err_code: 500,
message: err.message
})
})
app.listen(5555, () => {
console.log("服务启动成功......");
})
原文：https://www.cnblogs.com/samve/p/14274755.html