antd的upload组件，阻止默认上传事件，自定义

<Upload
  key="upload"
  beforeUpload={beforeUpload}
  className={styles.upload}
  accept=".png, .jpg, .jpeg, .bmp, mp4"
  listType="picture-card"
  showUploadList={false}
></Upload>;

//上传资源事件重写
const beforeUpload = (file) => {
  getBase64(file, (imageUrl) => {
    setloadimg(imageUrl);
    onSelectUploadImage(imageUrl);
  });
  return false;
};

//取图片base64
const getBase64 = (img, callback) => {
  const reader = new FileReader();
  reader.addEventListener(‘load‘, () => callback(reader.result));
  reader.readAsDataURL(img);
};