大文件分块上传

断点续传

断点续传需要为每个分块加md5值，如果用户取消上传，可以知道那些分块已经上传了

切块上传

只要校验整个文件的完整性就好

前端代码示例

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><title>大文件上传</title><style>body {padding: 24px;}button {padding: 8px 16px;cursor: pointer;border: 1px solid #409eff;border-radius: 4px;background-color: #409eff;color: #fff;margin-right: 16px;}.progress {width: 100%;height: 24px;background-color: #ebeef5;border-radius: 12px;margin-bottom: 24px;overflow: hidden;}.progress-inner {width: 0%;height: 100%;background-color: #67c23a;border-radius: 12px;text-align: right;transition: width 0.6s ease;}.progress-text {color: #fff;margin: 0 5px;display: inline-block;font-size: 12px;}</style></head><body><!-- 进度条 --><div class="progress"><div class="progress-inner"><div class="progress-text"></div></div></div><!-- 上传完显示预览地址 --><p><a id="filelink"></a></p><!-- 操作按钮 --><button id="upload"><input type="file" id="file" style="display: none" />上传文件</button><button id="download">下载文件</button><script src="https://unpkg.com/axios/dist/axios.min.js"></script><script src="https://unpkg.com/spark-md5@3.0.2/spark-md5.js"></script><script>// 上传document.querySelector("#upload").addEventListener("click", () => {document.querySelector("#file").click();});// 选中文件直接上传document.querySelector("#file").addEventListener("change", async (e) => {const file = e.target.files[0];// 获取文件的所有分块const blobList = getFileSlices(file);const uploadRequests = [];// 所有分块的md5值// 后端根据md5值存的块，请求合并根据md5值进行合并const md5ChunkList = [];let totalUploaded = 0;for (let i = 0; i < blobList.length; i++) {const blob = blobList[i];const md5 = await calculateMD5(blob);md5ChunkList.push(md5);const formData = new FormData();formData.append("file", blob);formData.append("md5", md5);const request = axios({method: "post",url: "http://localhost:3000/upload",data: formData,onUploadProgress: (progressEvent) => {totalUploaded += progressEvent.loaded;let percentCompleted = Math.floor((totalUploaded / file.size) * 100);// 为合并留1%进度条if (percentCompleted >= 100) {percentCompleted = 99;}updateProgressBar(percentCompleted);},});uploadRequests.push(request);}try {// 等待所有分块上传完成，再请求合并await Promise.all(uploadRequests);const { data } = await axios({method: "post",url: "http://localhost:3000/merge",data: { md5: md5ChunkList, fileName: file.name },});updateProgressBar(100);const url = `http://localhost:3000${data.data}`;console.log(url);const a = document.querySelector("#filelink");a.href = url;a.target = "_blank";a.innerText = url;} catch (e) {console.error(e);}});// 获取文件分块// 默认分块大小5mfunction getFileSlices(file, segmentSize = 5 * 1024 * 1024) {const fileSlices = [];let offset = 0;while (offset < file.size) {const segment = file.slice(offset, offset + segmentSize);fileSlices.push(segment);offset += segmentSize;}return fileSlices;}// 计算分块的md5值function calculateMD5(blob) {return new Promise((resolve, reject) => {const fileReader = new FileReader();let spark = new SparkMD5.ArrayBuffer();fileReader.onload = (e) => {spark.append(e.target.result);resolve(spark.end());};fileReader.onerror = () => {reject("blob读取失败");};fileReader.readAsArrayBuffer(blob);});}function updateProgressBar(percent) {const width = percent + "%";document.querySelector(".progress-inner").style.width = width;document.querySelector(".progress-text").innerText = width;}// 下载document.querySelector("#download").addEventListener("click", () => {const url = document.querySelector("#filelink").innerText;const fileName = url.substring(url.lastIndexOf("/") + 1);const download = document.createElement("a");download.href = `http://localhost:3000/download/${fileName}`;download.download = fileName;download.target = "_blank";download.click();});</script></body>
</html>

后端代码示例

import express from "express";
import cors from "cors";
import multer from "multer";
import fs from "fs";
import path from "path";
import mime from "mime-types";const app = express();
const port = 3000;
const upload = multer({ dest: "uploads/" });// 处理跨域请求
app.use(cors());
// 解析客户端请求中的JSON数据，解析后的对象将被添加到req.body
app.use(express.json());
// 启用对静态文件的服务
app.use("/uploads", express.static("uploads"));app.get("/", (req, res) => {res.send("Hello World!");
});// 上传
app.post("/upload", upload.single("file"), (req, res) => {const file = req.file;const md5 = req.body.md5;const newPath = path.join(path.dirname(file.path), md5);fs.renameSync(file.path, newPath);res.send({ code: 200 });
});// 合并
app.post("/merge", async (req, res) => {const { md5, fileName } = req.body;await concatFiles(md5, fileName);res.send({ code: 200, msg: "合并成功", data: `/uploads/${fileName}` });
});// 下载文件流
app.get("/download/:fileName", (req, res) => {const { fileName } = req.params;const file = path.join("./uploads", fileName);const type = mime.lookup(file);res.setHeader("Content-disposition","attachment; filename=" + encodeURIComponent(path.basename(file)));res.setHeader("Content-type", type);const filestream = fs.createReadStream(file);filestream.pipe(res);
});app.listen(port, () => {console.log(`listening on port ${port}`);
});// 合并切片的文件
async function concatFiles(fileChunks, name) {const filePath = path.join("./uploads", name);const writeStream = fs.createWriteStream(filePath);for (let i = 0; i < fileChunks.length; i++) {const chunkPath = path.join("./uploads", fileChunks[i]);const file = fs.createReadStream(chunkPath);file.pipe(writeStream, { end: false });// 等待当前文件读完再进行下一个await new Promise((resolve) => file.on("end", resolve));fs.unlink(chunkPath, (e) => {if (e) {console.error("删除文件切片失败", e);}});}writeStream.end();
}