Question: I am creating a Spring MVC Hibernate application using MySQL. Where should I save the User Images: in the database or in some folder, like under `WEB-INF/` ?

Answer: 
Certainly not inside WEB-INF. You might want to save them in the file system, but not in the webapp's directory. First of all, it could very well be inexistent, if the app is packaged as a war. And second, you would lose evrything as soon as you redeploy the app. Desktop apps don't store their user data in their install directory, do they? It should be the same for webapps.

Now, since images are usually big, and they're not searchable, you might want to store them on the file system, and only store their name, path, hash, and/or mime type into the database. But it depends on your application, if they need to be served/used by other applications, if these apps have access to the database and/or the file system, etc. You decide.
That depends what you're trying to accomplish.   

If these are static images , and you have a fixed number of users ,you can consider saving them under WEB-INF/.   

However, most likely this is not you case, and you have varying number amount of users and you have to store a user for each one of them.   

Possible solutions:   

A. For the user store an image name, and have a convention of storing/loading from a well known directory in your file system.   

B. Store the image as a blob in your DB. Consider checking the [@Lob annotation](http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html/entity.html)