利用Vue3+Element-plus实现大文件分片上传组件

<el-upload drag :file-list="fileList" :on-change="onUpload" :auto-upload="false" ref="uploadfile" :limit="1" :show-file-list="false" ></el-upload>

const onUpload = async (File:any) => {
	const chunkSize = 30 * 1024 * 1024; // 分片大小
	const file = File.raw // 文件
	const fileSize = File.size // 文件大小
	let chunkCount = Math.ceil(fileSize / chunkSize) // 分片数量
	if(chunkSize > fileSize){ // 文件过小就一片
	    chunkCount = 1
	}
	// 文件md5，给文件一个唯一标识
	const fileMd5 = await getFileMd5(file, chunkCount, chunkSize); 
	// 上传分片
	for( let i=0;i<chunkCount;i++) {
    	const start = i * chunkSize //分片开始
    	const end = Math.min(fileSize, start + chunkSize) // 分片结束
    	const _chunkFile = File.raw.slice(start, end) // 分片文件
    	// 定义分片上传接口参数，跟后端商定
    	const formdata = new FormData()
	    formdata.append('chunkNumber', i.toString())
	    formdata.append('chunkSize', _chunkFile.size)
	    formdata.append('file', _chunkFile)
	    formdata.append('fileName', File.name)
	    formdata.append('fileSign', fileMd5)
	    formdata.append('totalChunks', chunkCount.toString())
	    formdata.append('totalChunkSize', fileSize)
    
	    // 检查分片文件是否上传-没有上传则上传
	    const params = { chunkNumber: i, fileSign: fileMd5 }
    	const { data } = await checkChunkFile(params) // 检验接口-自己定义
	    if(!data.flag){
	      console.log("开始上传第" + i + "个分片")
	      await uploadChunkFile(formdata) // 上传接口-自己定义
	    }
  	}
  	
	// 合并
	const mergeData = { // 合并参数
	    fileName: File.name, 
	    fileSign: fileMd5,
	    ...
	 }
	mergeFile(mergeData)// 合并接口-自己定义
}

const getFileMd5 = (file: File, chunkCount: number, chunkSize: number) => {
  return new Promise((resolve, reject) => {
    const blobSlice = File.prototype.slice
    const chunks = chunkCount
    let currentChunk = 0
    const spark = new SparkMD5.ArrayBuffer()
    const fileReader = new FileReader()
    fileReader.onload = e => {
      spark.append(e.target?.result)
      currentChunk ++
      if(currentChunk < chunks){
        loadNext()
      } else {
        const md5 = spark.end()
        resolve(md5)
      }
    }
    fileReader.onerror = e => {
        reject(e)
    }
    function loadNext () {
        const start = currentChunk * chunkSize
        let end = start + chunkSize
        if(end > file.size){
            end = file.size
        }
        fileReader.readAsArrayBuffer(blobSlice.call(file, start, end))
    }
    loadNext()
  })
}