public function getDownloadUrl($bucket,$path,$oldfilename){
$this->obsClient = new ObsClient([
    'key' => env('huawei.key'),
    'secret' => env('huawei.secreat'),
    'endpoint' => 'obs.cn-south-1.myhuaweicloud.com',//替换成自己的endpoint
]);

$signedUrl = $this->obsClient->createSignedUrl(
    [
        'Method' => 'GET',
        'Bucket' => $bucket,
        'Key' => $path,
        'Expires' => 3600,
        'QueryParams' => [
            'response-content-disposition'=>'attachment;filename='.urlencode($oldfilename)
            ]
    ]
);
$signedUrl = $signedUrl['SignedUrl'];

}