File Upload Summary

When uploading a file to a traditional form form, be careful to add
Enctype= "Multipart/form-data"

If Multipart/form-data is used, the request must be in the form of a post

If use enctype= "Multipart/form-data", then in the process of file upload will automatically calculate the size of the file, and the content segmentation information boundary placed in the request header Content-type, as follows:
Content-type:multipart/form-data; Boundary=${bound}

This value is written by HTTP on its own calculation, so you don't have to set it manually.
If this value is set manually, HTTP does not update it
Sometimes the background report boundary error, it is possible to manually set the header in the Content-type value of the reason.

File Upload Summary