File upload sounds boring until you've spent an afternoon debugging MultipartException: Failed to parse multipart servlet request in production.
In Spring Boot, file upload involves MultipartFile, MultipartAutoConfiguration, spring.servlet.multipart.* properties, and a silent assumption that you're running on a servlet container. It works, but it carries a lot of hidden machinery.
Solon takes a different path. The core class is UploadedFile, it lives in the web layer with no extra configuration needed, and you have explicit control over when multipart parsing happens and when temporary files get cleaned up.
The Basics: UploadedFile
When a controller method includes an UploadedFile parameter, Solon automatically triggers multipart parsing — no annotation required:
