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For attachments such as pictures, videos and videos documents that have been restricted from downloading: users can preview, but cannot download, nor can they right-click > save as during preview.
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Upload an attachment first, delete it, and upload it again. Download this attachment at this time, this download may not be recorded in the attachment download history.
优化：
对于已经限制下载的图片、视频等附件：用户可以预览，但不能下载，也不能在预览时点击鼠标右键 对于已经限制下载的图片、视频、文档等附件：用户可以预览，但不能下载，也不能在预览时点击鼠标右键 > 另存为。
修复了：
先上传一个附件，将其删除后，再次上传。此时下载这个附件，附件下载历史记录中可能没有记录本次下载。