npm install koa-body --save

const koaBody = require('koa-body');

app.use(koaBody({
 multipart: true,
 formidable: {
  maxFileSize: 200 * 1024 * 1024 // 设置上传文件大小最大限制，默认2M
 }
}));

const errorResult = require('../utils/errorResult.js');
const uploadExcelSrv = require('../service/uploadExcelSrv');

const saveData = async function (ctx, next) {

 const getRes = await uploadExcelSrv.getExcelObjs(ctx);
 if (getRes.status) {
  if (getRes.datas.length > 1) {
   errorResult.errorRes(ctx, '暂时不支持多个sheet存在');
  } else { //得到的是数组
   const objs = getRes.datas[0];
   ctx.body = {
    status: true,
    msg: '上传数据成功'
   };
  }
 } else {
  errorResult.errorRes(ctx, getRes.msg);
 }
 await next();
};
module.exports = {
 saveData
};

npm install xlsx --save

//接收上传的excel文件，保存解析返回objects
const xlsx = require('xlsx');
const fs = require('fs');
const path = require('path');
const downPath = path.resolve(__dirname, '../../fileUpload');

async function getExcelObjs (ctx) {
 const file = ctx.request.files.file; // 获取上传文件
 const reader = fs.createReadStream(file.path); // 创建可读流
 const ext = file.name.split('.').pop(); // 获取上传文件扩展名
 const filePath = `${downPath}/${Math.random().toString()}.${ext}`;

 const upStream = fs.createWriteStream(filePath); // 创建可写流
 const getRes = await getFile(reader, upStream); //等待数据存储完成

 const datas = []; //可能存在多个sheet的情况
 if (!getRes) { //没有问题
  const workbook = xlsx.readFile(filePath);
  const sheetNames = workbook.SheetNames; // 返回 ['sheet1', ...]
  for (const sheetName of sheetNames) {
   const worksheet = workbook.Sheets[sheetName];
   const data = xlsx.utils.sheet_to_json(worksheet);
   datas.push(data);
  }
  return {
   status: true,
   datas
  };
 } else {
  return {
   status: false,
   msg: '上传文件错误'
  };
 }
}

function getFile (reader, upStream) {
 return new Promise(function (result) {
  let stream = reader.pipe(upStream); // 可读流通过管道写入可写流
  stream.on('finish', function (err) {
   result(err);
  });
 });
}
module.exports = {
 getExcelObjs
};