点击桶权限 ，添加策略

{"Version": "2012-10-17","Statement": [{"Sid": "AddPerm","Effect": "Allow","Principal": "*","Action": "s3:GetObject","Resource": "arn:aws:s3:::bucketname/foldername/*"}]
}

如果需要桶下面的所有全部公开访问

“Resource”: “arn:aws:s3:::bucketname/*”