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【实用案例】录音分片上传的核心逻辑和实现案例【文章附有代码】

news 2025/8/12 5:53:42

前言

最近接到一个业务需求：录音文件上传时因为文件过大（超过100M）有报错，
（服务器端对单次文件的上传，有大小限制）。
经过讨论，最后决定使用‘分片’解决问题。
我做了一个小案例（非业务代码），用HTML代码实现前端页面，用express实现后端服务。

一、分片上传的核心原理

分片上传是将大文件分割成多个小片段（分片），逐个上传到服务器，最后在服务器端合并所有分片形成完整文件的技术。这种方式的优势在于：

避免单次上传大文件导致的超时问题
支持断点续传，某分片失败只需重传该分片
减轻服务器单次处理压力，提高系统稳定性

对于录音文件来说，由于可能包含长时间的音频数据（尤其是高清录音），文件体积往往较大，非常适合采用分片上传方案。

二、前端实现核心逻辑

前端主要负责录音、文件分片和上传控制三个部分。

1. 录音功能实现

使用浏览器原生的MediaRecorderAPI 实现录音功能：

// 开始录音
startRecordBtn.addEventListener('click', async () => {const stream = await navigator.mediaDevices.getUserMedia({ audio: true });mediaRecorder = new MediaRecorder(stream);audioChunks = [];mediaRecorder.ondataavailable = (event) => {audioChunks.push(event.data);};mediaRecorder.start();// 更新UI状态...
});// 停止录音
stopRecordBtn.addEventListener('click', () => {mediaRecorder.stop();mediaRecorder.stream.getTracks().forEach(track => track.stop());mediaRecorder.onstop = () => {audioBlob = new Blob(audioChunks, { type: 'audio/webm' });audioUrl = URL.createObjectURL(audioBlob);// 显示上传区域...};
});

2. 分片上传核心实现

创建AudioChunkUploader类处理分片逻辑：

class AudioChunkUploader {constructor(options) {this.options = {chunkSize: 5 * 1024 * 1024, // 5MB每片uploadUrl: 'http://localhost:3000/upload/chunk',mergeUrl: 'http://localhost:3000/upload/merge',...options};this.state = {totalChunks: 0,uploadedChunks: 0,fileMd5: '', // 文件唯一标识isPaused: false};}// 计算文件MD5（用于标识同一文件）async _calculateFileMd5() {return new Promise((resolve) => {const fileReader = new FileReader();const spark = new SparkMD5.ArrayBuffer();fileReader.onload = (e) => {spark.append(e.target.result);this.state.fileMd5 = spark.end();resolve();};fileReader.readAsArrayBuffer(this.options.file);});}// 上传单个分片async _uploadSingleChunk(chunkIndex) {const start = chunkIndex * this.options.chunkSize;const end = Math.min(start + this.options.chunkSize, this.state.fileSize);const chunk = this.options.file.slice(start, end);const formData = new FormData();formData.append('chunk', chunkIndex);formData.append('chunks', this.state.totalChunks);formData.append('fileMd5', this.state.fileMd5);formData.append('file', chunk);return fetch(this.options.uploadUrl, {method: 'POST',body: formData}).then(response => response.json());}// 上传所有分片async _uploadChunks() {for (let i = 0; i < this.state.totalChunks; i++) {if (this.state.isPaused) {// 等待恢复上传await new Promise(resolve => {const check = setInterval(() => {if (!this.state.isPaused) {clearInterval(check);resolve();}}, 100);});}await this._uploadSingleChunk(i);this.state.uploadedChunks = i + 1;// 触发进度更新...}}// 通知服务器合并分片async _mergeChunks() {return fetch(this.options.mergeUrl, {method: 'POST',headers: { 'Content-Type': 'application/json' },body: JSON.stringify({fileMd5: this.state.fileMd5,fileName: this.options.fileName,chunks: this.state.totalChunks})}).then(response => response.json());}
}

3. 播放控制功能

实现带暂停 / 继续功能的音频播放：

let audioPlayer = null;
let lastPlayTime = 0;// 播放录音
playRecordBtn.addEventListener('click', () => {if (!audioPlayer) {audioPlayer = new Audio(audioUrl);if (lastPlayTime > 0) {audioPlayer.currentTime = lastPlayTime;}} else {audioPlayer.currentTime = lastPlayTime;}audioPlayer.play();// 更新按钮状态...
});// 暂停播放
stopPlayBtn.addEventListener('click', () => {lastPlayTime = audioPlayer.currentTime;audioPlayer.pause();// 更新按钮状态...
});

三、后端实现核心逻辑

Express 后端负责接收分片、临时存储和合并文件：

1. 分片接收接口

const multer = require('multer');
const upload = multer({ storage: multer.diskStorage({destination: (req, file, cb) => {// 为每个文件创建独立的临时目录const chunkDir = path.join(tempDir, req.body.fileMd5);if (!fs.existsSync(chunkDir)) {fs.mkdirSync(chunkDir, { recursive: true });}cb(null, chunkDir);},filename: (req, file, cb) => {// 用分片索引作为文件名cb(null, req.body.chunk);}})
});// 处理分片上传
app.post('/upload/chunk', upload.single('file'), (req, res) => {res.json({success: true,message: `分片 ${req.body.chunk} 上传成功`});
});

2. 分片合并接口

app.post('/upload/merge', (req, res) => {const { fileMd5, fileName, chunks } = req.body;const chunkDir = path.join(tempDir, fileMd5);const destPath = path.join(uploadDir, fileName);// 检查所有分片是否上传完成if (fs.readdirSync(chunkDir).length !== parseInt(chunks)) {return res.status(400).json({success: false,message: '分片不完整'});}// 合并分片const writeStream = fs.createWriteStream(destPath);let chunkIndex = 0;const mergeNextChunk = () => {const chunkPath = path.join(chunkDir, chunkIndex.toString());if (fs.existsSync(chunkPath)) {const readStream = fs.createReadStream(chunkPath);readStream.pipe(writeStream, { end: false });readStream.on('end', () => {fs.unlinkSync(chunkPath); // 删除已合并的分片chunkIndex++;mergeNextChunk();});} else {writeStream.end(); // 所有分片合并完成}};mergeNextChunk();writeStream.on('finish', () => {fs.rmdirSync(chunkDir, { recursive: true }); // 清理临时目录res.json({success: true,fileName,filePath: destPath});});
});