When you are writing a project recently, you will need to upload images in a lot of places. Do you want to write a total upload file(including individual files, database tables, controller, etc.), or do you want to copy and paste it wherever it is useful?

1, that must be to write a public, so that we do not have to repeat to write, behind the maintenance is convenient, only need to change a place can, greatly improve the development efficiency;
2, if you write more than one word, maintenance trouble, need to find one by one, sometimes will miss;
3. If the upload of a certain place is special, there are many restrictions, but the underlying functions of the upload remain unchanged, only more restrictions are needed, such as only uploading pdf, the size is limited to 2M, etc., and this special need only to write a single check.