Question

I really like functional programming, I like its immutability concepts and also it’s no side-effects concepts for functions.

I’m trying to take some of these concepts into java.

Now I have some kind of a servlet which receives a request and if browser did not send a cookie to server then i would like to create a cookie with a certain path to the user.

now inside the servlet i don’t want to hold that logic because its common to multiple servlets.
so i extract it into some kind of a cookie manager which will do that:

CookieManager.java.handleCookies(request, response)

1. Check if browser sent cookie.
2. If not set cookie with new session cookie value with certain path.

however i don’t like it because now the servlet will call the CookieManager.java.handleCookie will have a side effect I would rather it to return some kind of a response and further use it in my servlet wihtout having it effect its parameters that i’m passing into it.

anyone can suggest a solution which would both be elegant, no side effects, and excellent in performance?

thanks

Answer 1

You can make use of servlet filter. It would be well suited for your case. You can map your filter to URL pattern and write your code inside dofilter method. Filters are recommended if you want to have pre and post prcoess of request/response. Since you are doing preprocess for you request it would fit in your case. If is also loosely coupled, because you can remove it, modify it, or add another rule anytime without modifying the core servlet code.