Node.js實(shí)現(xiàn)分片上傳斷點(diǎn)續(xù)傳示例詳解

更新時(shí)間：2022年07月29日 09:22:18 作者：來了老弟

這篇文章主要為大家介紹了Node.js實(shí)現(xiàn)分片上傳斷點(diǎn)續(xù)傳示例詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步，早日升職加薪

正文

大文件上傳會(huì)消耗大量的時(shí)間，而且中途有可能上傳失敗。這時(shí)我們需要前端和后端配合來解決這個(gè)問題。

解決步驟：

文件分片，減少每次請(qǐng)求消耗的時(shí)間，如果某次請(qǐng)求失敗可以單獨(dú)上傳，而不是從頭開始
通知服務(wù)端合并文件分片
控制并發(fā)的請(qǐng)求數(shù)量，避免瀏覽器內(nèi)存溢出
當(dāng)因?yàn)榫W(wǎng)絡(luò)或者其他原因?qū)е履炒蔚恼?qǐng)求失敗，我們重新發(fā)送請(qǐng)求

文件的分片與合并

在JavaScript中，F(xiàn)Ile對(duì)象是' Blob '對(duì)象的子類，該對(duì)象包含一個(gè)重要的方法slice，通過該方法我們可以這樣分割二進(jìn)制文件:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/axios/0.24.0/axios.min.js"></script>
</head>
<body>
    <input type="file" multiple="multiple" id="fileInput" />
    <button onclick="SliceUpload()">上傳</button>  
    <script>
        function SliceUpload() {
            const file = document.getElementById('fileInput').files[0]
            if (!file) return
            // 文件分片
            let size = 1024 * 50; //50KB 50KB Section size
            let fileChunks = [];
            let index = 0;        //Section num
            for (let cur = 0; cur < file.size; cur += size) {
                fileChunks.push({
                    hash: index++,
                    chunk: file.slice(cur, cur + size),
                });
            }
            // 上傳分片
            const uploadList = fileChunks.map((item, index) => {
                let formData = new FormData();
                formData.append("filename", file.name);
                formData.append("hash", item.hash);
                formData.append("chunk", item.chunk);
                return axios({
                    method: "post",
                    url: "/upload",
                    data: formData,
                });
            });
            await Promise.all(uploadList);
            // 所有分片上傳完成，通知服務(wù)器合并分片
            await axios({
                method: "get",
                url: "/merge",
                params: {
                    filename: file.name,
                },
            });
            console.log("Upload to complete");
        }
    </script>
</body>
</html>

并發(fā)控制

如果文件很大，這樣切分的分片會(huì)很多，瀏覽器短時(shí)間內(nèi)就會(huì)發(fā)起大量的請(qǐng)求，可能會(huì)導(dǎo)致內(nèi)存耗盡，所以要進(jìn)行并發(fā)控制。

這里我們結(jié)合Promise.race()方法控制并發(fā)請(qǐng)求的數(shù)量，避免瀏覽器內(nèi)存溢出。

// 加入并發(fā)控制
async function SliceUpload() {
    const file = document.getElementById('fileInput').files[0]
    if (!file) return
    // 文件分片
    let size = 1024 * 50; //50KB 50KB Section size
    let fileChunks = [];
    let index = 0;        //Section num
    for (let cur = 0; cur < file.size; cur += size) {
        fileChunks.push({
            hash: index++,
            chunk: file.slice(cur, cur + size),
        });
    }
    let pool = []; //Concurrent pool
    let max = 3; //Maximum concurrency
    for (let i = 0; i < fileChunks.length; i++) {
        let item = fileChunks[i];
        let formData = new FormData();
        formData.append("filename", file.name);
        formData.append("hash", item.hash);
        formData.append("chunk", item.chunk);
        // 上傳分片
        let task = axios({
            method: "post",
            url: "/upload",
            data: formData,
        });
        task.then(() => {
        // 從并發(fā)池中移除已經(jīng)完成的請(qǐng)求
        let index = pool.findIndex((t) => t === task);
            pool.splice(index);
        });
        // 把請(qǐng)求放入并發(fā)池中，如果已經(jīng)達(dá)到最大并發(fā)量
        pool.push(task);
        if (pool.length === max) {
            //All requests are requested complete
            await Promise.race(pool);
        }
    }
    // 所有分片上傳完成，通知服務(wù)器合并分片
    await axios({
        method: "get",
        url: "/merge",
        params: {
            filename: file.name,
        },
    });
    console.log("Upload to complete");
}

使代碼可復(fù)用

function SliceUpload() {
    const file = document.getElementById('fileInput').files[0]
    if (!file) return
    // 文件分片
    let size = 1024 * 50; // 分片大小設(shè)置
    let fileChunks = [];
    let index = 0;        // 分片序號(hào)
    for (let cur = 0; cur < file.size; cur += size) {
        fileChunks.push({
            hash: index++,
            chunk: file.slice(cur, cur + size),
        });
    }
    const uploadFileChunks = async function(list){
        if(list.length === 0){
            // 所有分片上傳完成，通知如無(wú)
            await axios({
                method: 'get',
                url: '/merge',
                params: {
                    filename: file.name
                }
            });
            console.log('Upload to complete')
            return
        }
        let pool = []       // 并發(fā)池
        let max = 3         // 最大并發(fā)數(shù)
        let finish = 0      // 完成數(shù)量
        let failList = []   // 失敗列表
        for(let i=0;i<list.length;i++){
            let item = list[i]
            let formData = new FormData()
            formData.append('filename', file.name)
            formData.append('hash', item.hash)
            formData.append('chunk', item.chunk)
            let task = axios({
                method: 'post',
                url: '/upload',
                data: formData
            })
            task.then((data)=>{
                // 從并發(fā)池中移除已經(jīng)完成的請(qǐng)求
                let index = pool.findIndex(t=> t===task)
                pool.splice(index)
            }).catch(()=>{
                failList.push(item)
            }).finally(()=>{
                finish++
                // 如果有失敗的重新上傳
                if(finish===list.length){
                    uploadFileChunks(failList)
                }
            })
            pool.push(task)
            if(pool.length === max){
                await Promise.race(pool)
            }
        }
    }
    uploadFileChunks(fileChunks)
}

服務(wù)端接口實(shí)現(xiàn)

const express = require('express')
const multiparty = require('multiparty')
const fs = require('fs')
const path = require('path')
const { Buffer } = require('buffer')
// file path
const STATIC_FILES = path.join(__dirname, './static/files')
// Temporary path to upload files
const STATIC_TEMPORARY = path.join(__dirname, './static/temporary')
const server = express()
// Static file hosting
server.use(express.static(path.join(__dirname, './dist')))
// Interface for uploading slices
server.post('/upload', (req, res) => {
    const form = new multiparty.Form();
    form.parse(req, function(err, fields, files) {
        let filename = fields.filename[0]
        let hash = fields.hash[0]
        let chunk = files.chunk[0]
        let dir = `${STATIC_TEMPORARY}/${filename}`
        // console.log(filename, hash, chunk)
        try {
            if (!fs.existsSync(dir)) fs.mkdirSync(dir)

以上就是Node.js實(shí)現(xiàn)分片上傳示例詳解的詳細(xì)內(nèi)容，更多關(guān)于Node.js分片上傳的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章！

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