參考文章：https://segmentfault.com/q/1010000010201366

前端：

<template>
    <el-upload action="test" :headers="importHeaders"></el-upload>
</template>

<script>
var mytoken =  localStorage.getItem('token') // 要保證取到

export default {
    data () {
        return {
            importHeaders: {token: mytoken}
        }
    }
}
</script>

後端：

@PostMapping("/test")
public R upload(MultipartFile file, HttpServletRequest request) {
    String token=request.getHeader("token");
    System.out.println("獲取token==="+token);

}