To get a servlet request in Struts 2 we can use either ServletRequestAware or ServletActionContext. However, in a particular internet resource, it is told that ServletRequestAware should be used instead of ServletActionContext.
Does that have something to do with the fact that ServletActionContext will be a shared resource in a multi-threaded environment or is there any other reason behind this?
The ServletActionContext is a helper class that contains only static methods, one of them used to retrieve servlet request from action context.
But action context is ThreadLocal, so it can't be shared in multi-threaded environment.
There's also no multi-threded environment per request in Struts2, except a background thread used by the execAndWait interceptor.
The reason to use ServletRequestAware is because it's guaranteed method to obtain a servlet request object if servletConfig interceptor is included in the stack.
You can use ServletActionContext from anywhere, but it doesn't guarantee that a request object instead of null will be returned.