Web pdf tag a with download is not valid only preview

I implement preview pdf in web. As long as the href to the file link browser will preview automatically, but I add the download attribute under the a tag or just preview but not download. How to solve this?

Mar.05,2021
The attribute of the

a tag only applies to the same origin URLs, cross-domain, which causes the download attribute to be invalid.
clipboard.png

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e9f900-691d9.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e9f900-691d9.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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