使用threads.modify()或messages.modify()(取决于您要执行的操作)，并使用"UNREAD"的removeLabelId.>

https://developers.google.com/gmail/api/v1/reference/users/threads/modify

How do I mark mail as read using Gmail API?

I got the thread of email

Thread thread = service.users().threads().get(userId, message.getThreadId()).execute();

but it does not have method markRead like gmail API site says it should.

use either threads.modify() or messages.modify() (depending on scope of what you want to do) and removeLabelId of "UNREAD".

https://developers.google.com/gmail/api/v1/reference/users/threads/modify