React+Node实现大文件分片上传、断点续传秒传思路

const md5File = (file) => {
    return new Promise((resolve, reject) => {
      // 文件截取
      let blobSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.WEBkitSlice,
        chunkSize = file?.size / 100,
        chunks = 100,
        currentChunk = 0,
        spark = new SparkMD5.ArrayBuffer(),
        fileReader = new FileReader();

      fileReader.onload = function (e) {
        console.log('read chunk nr', currentChunk + 1, 'of', chunks);
        spark.append(e.target.result);
        currentChunk += 1;

        if (currentChunk < chunks) {
          loadNext();
        } else {
          let result = spark.end()
          resolve(result)
        }
      };

      fileReader.onerror = function () {
        message.error('文件读取错误')
      };

      const loadNext = () => {
        const start = currentChunk * chunkSize,
          end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize;

        // 文件切片
        fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));
        // 检查进度条
        dispatch({ type: 'check', checkPercent: currentChunk + 1 })
      }

      loadNext();
    })
  }

app.get('/check/file', (req, resp) => {
  let query = req.query
  let fileName = query.fileName
  let fileMd5Value = query.fileMd5Value
  // 获取文件Chunk列表
  getChunkList(
      path.join(uploadDir, fileName),
      path.join(uploadDir, fileMd5Value),
      data => {
          resp.send(data)
      }
  )
})

// 获取文件Chunk列表
async function getChunkList(filePath, folderPath, callback) {
  let isFileExit = await isExist(filePath)
  let result = {}
  // 如果文件已在存在, 不用再继续上传, 真接秒传
  if (isFileExit) {
      result = {
          stat: 1,
          file: {
              isExist: true,
              name: filePath
          },
          desc: 'file is exist'
      }
  } else {
      let isFolderExist = await isExist(folderPath)
      // 如果文件夹(md5值后的文件)存在, 就获取已经上传的块
      let fileList = []
      if (isFolderExist) {
          fileList = await listDir(folderPath)
      }
      result = {
          stat: 1,
          chunkList: fileList,
          desc: 'folder list'
      }
  }
  callback(result)
}

if (data?.file) {
  message.success('文件已秒传')
  return
}

  async function checkAndUploadChunk(file, fileMd5Value, chunkList) {
    let chunks = Math.ceil(file.size / chunkSize)
    const requestList = []
    for (let i = 0; i < chunks; i++) {
      let exit = chunkList.indexOf(i + "") > -1
      // 如果不存在，则上传
      if (!exit) {
        requestList.push(upload({ i, file, fileMd5Value, chunks }))
      }
    }

    // 并发上传
    if (requestList?.length) {
      await Promise.all(requestList)
    }
  }

    // 上传chunk
  function upload({ i, file, fileMd5Value, chunks }) {
    current = 0
    //构造一个表单，FORMData是HTML5新增的
    let end = (i + 1) * chunkSize >= file.size ? file.size : (i + 1) * chunkSize
    let form = new FormData()
    form.append("data", file.slice(i * chunkSize, end)) //file对象的slice方法用于切出文件的一部分
    form.append("total", chunks) //总片数
    form.append("index", i) //当前是第几片     
    form.append("fileMd5Value", fileMd5Value)
    return axiOS({
      method: 'post',
      url: BaseUrl + "/upload",
      data: form
    }).then(({ data }) => {
      if (data.stat) {
        current = current + 1
        const uploadPercent = Math.ceil((current / chunks) * 100)
        dispatch({ type: 'upload', uploadPercent })
      }
    })
  }

app.all('/upload', (req, resp) => {
  const form = new formidable.IncomingForm({
      uploadDir: 'nodeServer/tmp'
  })
  form.parse(req, function(err, fields, file) {
      let index = fields.index
      let fileMd5Value = fields.fileMd5Value
      let folder = path.resolve(__dirname, 'nodeServer/uploads', fileMd5Value)
      folderIsExit(folder).then(val => {
          let destFile = path.resolve(folder, fields.index)
          copyFile(file.data.path, destFile).then(
              successLog => {
                  resp.send({
                      stat: 1,
                      desc: index
                  })
              },
              errorLog => {
                  resp.send({
                      stat: 0,
                      desc: 'Error'
                  })
              }
          )
      })
  })

  
  function notifyServer(file, fileMd5Value) {
    let url = BaseUrl + '/merge?md5=' + fileMd5Value + "&fileName=" + file.name + "&size=" + file.size
    axios.get(url).then(({ data }) => {
      if (data.stat) {
        message.success('上传成功')
      } else {
        message.error('上传失败')
      }
    })
  }

// 合成
app.all('/merge', (req, resp) => {
  let query = req.query
  let md5 = query.md5
  let fileName = query.fileName
  console.log(md5, fileName)
  mergeFiles(path.join(uploadDir, md5), uploadDir, fileName)
  resp.send({
      stat: 1
  })
})


// 合并文件
async function mergeFiles(srcDir, targetDir, newFileName) {
  let fileArr = await listDir(srcDir)
  fileArr.sort((x,y) => {
      return x-y;
  })
  // 把文件名加上文件夹的前缀
  for (let i = 0; i < fileArr.length; i++) {
      fileArr[i] = srcDir + '/' + fileArr[i]
  }
  concat(fileArr, path.join(targetDir, newFileName), () => {
      console.log('合成成功!')
  })
}