先贴个github链接(私有链接)COS-Case
主要思路:前端接受文件后，向后端获取签名，然后直接传入COS
前端

import {Button, Upload} from "antd";
import {UploadOutlined} from '@ant-design/icons';
import {getAuthorization} from "../../request";
import COS from "cos-js-sdk-v5";
import {useEffect, useState} from "react";

const prop = {
    Bucket: 'test-1111111',//桶名称
    Region: 'ap-shanghai',//桶地域
    Key: '1.jpg',
    Body: null,
}


const FileItem = () => {
    const [cos, setCos] = useState({})

    useEffect(() => {
        let cos = new COS({
            getAuthorization: async function (options, callback) {
            	// 获取认证
                let res = await getAuthorization()
                console.log(res)
                callback({
                    TmpSecretId: res.secrectId,  //密钥id
                    TmpSecretKey: res.secretKey, // 密钥
                    SecurityToken: "eybToken", // token
                    StartTime: res.startTime, // 开始时间，时间戳，最好用服务器时间
                    ExpiredTime: res.expireTime, // 截止时间，时间戳
                })
            }
        })
        setCos(cos)
    }, [])

    const beforeUpload = async (e) => {
        console.log(e)
        prop.Body = e
        //上传文件
        let data = await cos.uploadFile(prop)
        console.log(data)
        return false
    }

    const downloadFile = () => {
        cos.getObjectUrl(prop,(err,data)=>{
            if(err) return console.log(err)
            console.log(data)
            //response-content-disposition=attachment 用于指定以什么样的格式打开，attachment即附件
            let downLoadUrl = data.Url+(data.Url.indexOf('?')>-1?'&':'?') + 'response-content-disposition=attachment'
            //是否重命名
            downLoadUrl +=';filename=myname.jpg'
            window.open(downLoadUrl)
        })
    }

    const props = {
        name: '',
        action: '', //上传的地址
        headers: {
            authorization: 'authorization-text',
        },
        beforeUpload,
    }



    return (
        <>
            <Upload {...props} >
                <Button icon={<UploadOutlined/>}>Click to Upload</Button>
            </Upload>
            <Button onClick={downloadFile}>
                Click to DownLoad File
            </Button>
        </>
    )
}

export default FileItem

后端

package services

import (
	"github.com/gin-gonic/gin"
	"time"
)

type Secret struct {
	SECRECTID  string `json:"secrectId"`
	SECRETKEY  string `json:"secretKey"`
	STARTTIME  int64  `json:"startTime"`
	EXPIRETIME int64  `json:"expireTime"`
}

type Response struct {
	Code    string      `json:"code"`
	Data    interface{} `json:"data"`
	Message string      `json:"message"`
}

const SECRECTID string = "111" //你的腾讯云secretId
const SECRETKEY string = "222"     //你的腾讯云secretKey

func GetAuthorization(cilent *gin.Context) {
	s := Secret{SECRECTID: SECRECTID, SECRETKEY: SECRETKEY, STARTTIME: time.Now().Unix(), EXPIRETIME: time.Now().Add(time.Second * 60).Unix()}
	cilent.Header("Access-Control-Allow-Origin", "*")

	cilent.JSON(200, Response{
		Code:    "0",
		Data:    s,
		Message: "successful",
	})
	return
}

Q.E.D.