Node.js Koa 实现图片上传与静态回显完整教程

//main.js
const Koa = require('koa') // 引入koa
const Router = require('koa-router') // 引入koa-router
const koaBody = require('koa-body')
router.get('/', async (ctx) => {
    ctx.type = 'html'
    ctx.body = '<h1>hello world!</h1>'
})
app.use(router.routes())
    .use(router.allowedMethods())
    .use(koaBody())

// 启动服务监听本地3000端口
app.listen(3000, () => {
    console.log('应用已经启动，http://localhost:3000')
})

//mian.js 新增代码
const serve = require('koa-static')
const path = require('path')
app.use(serve(path.join(__dirname, './upload')))

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <input type="file" class="file" name="avatar">
  <button onclick="send()">上传</button>
  <script src="https://unpkg.com/axios/dist/axios.min.js"></script>
  <script>
    let formData = new FormData()
    document.querySelector('.file').addEventListener('change', function(e) {
          let files = e.target.files
          console.log(files)
          if (!files.length) return
          formData.append('file', files[0], files[0].name)
        })
        function send(){
          axios.post('http://localhost:3000/upload',formData,{
            Headers:{
              "Content-type":"multipart/form-data"
            }
          })
        }
  </script>
</body>
</html>

//mian.js新增代码
const cors = require('koa2-cors')
app.use(cors())//注意这个配置要在router前使用不然不生效

router.post('/upload', async (ctx) => {
    ctx.body = 'ok'
})

const multer = require('@koa/multer')
const storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, './upload')
    },
    filename: function (req, file, cb) {
        const fileFormat = (file.originalname).split('.')
        cb(null, Date.now() + '.' + fileFormat[fileFormat.length - 1])
    }
})
const upload = multer({ storage })

router.post('/upload', upload.single('file'), async (ctx) => {
    console.log('ctx.request.body', ctx.request.body)
    ctx.body = 'done'
})