Chapter plan
What you will complete
01Multipart Uploads & File ValidationAccept files through multipart/form-data with explicit limits and content checks—never trusting names, types, or sizes the client claims.Bind MultipartFile in a controller with size limits configuredValidate real media type and sanitize stored filenamesStream uploads so memory does not scale with file size 30 min02Object Storage & Presigned URLsMove files behind S3-compatible object storage, upload through the app or direct presigned PUTs, and keep private objects genuinely private.Abstract storage behind an interface so local and cloud swap freelyUpload with the SDK or hand clients time-boxed presigned URLsServe downloads through expiring presigned GETs after authorization 35 min
Module outcome
Ship an upload feature that bounds memory, blocks malicious files, and keeps private files private.
Mental model
An upload is untrusted input that happens to be large: validate content, stream bytes, and never serve user paths directly.
Module checkpoint
Task attachments
Attach validated documents to tasks with size limits and access control.
- Oversized and wrong-type uploads rejected cleanly
- Files streamed without heap spikes
- Private files unreachable without authorization
Final module assessment
Ready to prove mastery?
Complete all 50 questions after finishing the module lessons and checkpoint.