<input type="file" id="file">
    

function upload() {
      var formData = new FormData();
      var fileField = document.querySelector("#file");
      const file = fileField.files[0];
      formData.append('inputFile', file);
      fetch('/upload', {
        method: 'POST',
        body: formData,
      })
        .then(res => res.json())
        .then(res => {
          document.querySelector("#url").value = res.url
        });
    }

const upload = require('multer')();
const router = require('express').Router();

router.post('/upload', upload.fields([{ name: 'inputFile' }]), async (req, res) => {
  //文件
  const file = req.files['inputFile'][0];
  const md5Name = crypto
  .createHash('md5')
  .update(file.buffer, 'utf-8')
  .digest('hex');//计算出上传文件的md5,当文件名
  const extname = path.extname(file.originalname)//后缀名
  // 存储到cos的路径
  const Key = '/upload/' + md5Name + extnam

  try {
    // 利用自己封装的腾讯oss 上传模块
    const { url } = await oss.upload({
      Key: Key,
      Body: file.buffer
    });
    res.send({
      code: 200,
      data: file.originalname,
      url
    })

  } catch (error) {
    res.send({ code: 500, msg: error })
  }
});

const bytesPerPiece = 4 * 1024 * 1024; // 每个文件切片大小定为5MB .

function upload() {
  var formData = new FormData();
  var fileField = document.querySelector("#file");
  const file = fileField.files[0];
  const { size } = file;
  // 大于5M，分片上传
  if (size > bytesPerPiece) {
    chunkUpload(file)
  } else {

    formData.append('inputFile', file);

    fetch('/upload', {
      method: 'POST',
      body: formData,
    })
      .then(res => res.json())
      .then(res => {
        document.querySelector("#url").value = res.url
      });
  }
}
// 切割并分片上传
async function chunkUpload(file) {
  const { size, name, type } = file;
  // 分片上传
  let index = 0;
  const totalPieces = Math.ceil(size / bytesPerPiece);
  console.time('上传完成')

  while (index < totalPieces) {
    const start = index * bytesPerPiece;
    let end = start + bytesPerPiece;
    if (end > size) {
      end = size
    }
    const chunk = file.slice(start, end);//切割文件
    const sliceIndex = `${name}.${index}`;
    const formData = new FormData();

    formData.append("chunk", chunk)
    formData.append("fileName", name)
    formData.append("chunkName", sliceIndex);

    console.log(formData)

    await fetch('/uploadChunk', {
      method: 'POST',
      body: formData,
    });
    index++
  }
  
  console.timeEnd('上传完成')
  console.log('上传完成')

  fetch('/joinChunk', {
    method: 'post',
    headers: {
      'Content-Type': "application/json;charset=UTF-8"
    },
    body: JSON.stringify({ 'fileName': name })
  })
    .then(res => res.json())
    .then(res => {
      document.querySelector("#url").value = res.url
    })

}

router.post('/uploadChunk', upload.fields([{ name: 'chunk' }]), async (req, res) => {
  const file = req.files['chunk'][0];//文件名
  const buffer = file.buffer;
  const { chunkName, fileName } = req.body;

  const chunkPath = join(__dirname, `../temp/chunk/${fileName}`, chunkName)
  const filePath = join(__dirname, `../temp/chunk/${fileName}`)

  if (!fs.existsSync(filePath)) {
    fs.mkdirSync(filePath);
  }

  fs.writeFileSync(chunkPath, buffer);

  res.send({
    code: 200,
    data: filePath,
    msg: `${chunkName}上传成功`
  })
});

router.post('/joinChunk', async (req, res) => {
  const { fileName } = req.body;
  console.log(req.body)
  const dir = join(__dirname, `../temp/chunk/${fileName}`)
  const file = join(__dirname, `../temp/file/${fileName}`)
  const files = fs.readdirSync(dir);

  files
    .sort((a, b) => {
      const aNum = Number(a.split('.').pop())
      const bNum = Number(b.split('.').pop());
      return aNum > bNum ? 1 : -1
    });

  files.forEach(chunkName => {
    const chunkUrl = join(dir, chunkName)
    const buffer = fs.readFileSync(chunkUrl);

    fs.appendFileSync(file, buffer)
    fs.unlinkSync(chunkUrl)

  });

  fs.rmdirSync(dir);
  const fullFile = fs.readFileSync(file)

  const md5Name = crypto.createHash('md5').update(fullFile, 'utf-8').digest('hex');//计算出上传文件的md5,当做文件名
  const extname = path.extname(file);//后缀名
  const Key = '/upload/' + md5Name + extname// 存储到cos的路径
  console.log(Key)
  try {
    const { url } = await oss.upload({
      Key: Key,
      Body: fullFile
    });
    res.send({
      code: 200,
      data: fileName,
      url
    })

  } catch (error) {
    res.send({ code: 500, msg: error })
  } finally {
    fs.unlinkSync(file)
  }
})