npm install --save busboy

const inspect = require('util').inspect 
const path = require('path')
const fs = require('fs')
const Busboy = require('busboy')

// req 为node原生请求
const busboy = new Busboy({ headers: req.headers })

// ...

// 监听文件解析事件
busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
  console.log(`File [${fieldname}]: filename: ${filename}`)


  // 文件保存到特定路径
  file.pipe(fs.createWriteStream('./upload'))

  // 开始解析文件流
  file.on('data', function(data) {
    console.log(`File [${fieldname}] got ${data.length} bytes`)
  })

  // 解析文件结束
  file.on('end', function() {
    console.log(`File [${fieldname}] Finished`)
  })
})

// 监听请求中的字段
busboy.on('field', function(fieldname, val, fieldnameTruncated, valTruncated) {
  console.log(`Field [${fieldname}]: value: ${inspect(val)}`)
})

// 监听结束事件
busboy.on('finish', function() {
  console.log('Done parsing form!')
  res.writeHead(303, { Connection: 'close', Location: '/' })
  res.end()
})
req.pipe(busboy)