利用file里面的slice方法可以将文件切片，前端进行切片处理向http并发传递。等所有切片上传完成后再向服务器发送一个合并切片的请求。

<input type="file" @change="onChange" ref="fileInput" />

onChange() {
  let self = this;
  let file = this.$refs.fileInput.files[0];
  if (!file) return;
  // 这里我们将切片固定成六分，也可以固定大小上传
  let axiosArray = [];
  let chunkList = [];
  let chunkSize = file.size / 6;
  let current = 0;
  let i = 0;
  let fileName = Date().getTime() + "_" + file.name;
  while (current < 6) {
    chunkList.push({
      chunk: file.slice(current * chunkSize, (current + 1) * chunkSize),
      fileName: current + "_" + fileName
    });
    current++;
  }
  // 切片并发传给后端，这里我们要注意切片上传时请求头是 multipart/form-data 合并切片时请求头是x-www-form-urlencoded，只能上传键值对
  chunkList.map(function(item) {
    let form = new FormData();
    form.append("file", item.chunk);
    form.append("fileName", item.fileName);
    axiosArray.push(
      self.$axios.post("/api/album/upload", form, {
        headers: { "Content-Type": "multipart/form-data" }
      })
    );
  });
  // 所有切片上传成功后合并
  Promise.all(axiosArray).then(res => {
    self.$axios.post("/api/album/uploadMerge", `fileName=${fileName}`);
  });
}