How to access a running servlet filter?

Question

I will be creating a ServletFilter that will alter the way HTTP Requests are processed.

The ServletFilter will make those decisions based on the state of the data in the database.

I would rather not have a database hit happen every time the ServletFilter is invoked.

The webapp already has quartz implemented, so hitting the database at a predetermined time is not a problem.

My question is, how can I contact the ServeltFilter at these timed intervals to give it a new set of saved information until the next timed interval?

Update: There is useful discussion in this SOF post about getting a ServletContext into a Quartz job. How to get and set a global object in Java servlet context

Ew. Wrong way 'round; should be a service both the filter and servlet can call. — Dave Newton, May 11 '12 at 13:18

score 1 · Answer 1 · edited Nov 25 '14 at 01:00

The short answer is: Yes you can, but though I would not recommend it, since your update functionality should not be located there but in a class responsible for that task, this improves cohesion.

If you'd like to know how to get the filter, take a look at this method in the javadoc.

ServletContext.getFilterRegistration()
The Servlet context instance can be obtained by calling this method:

ServletContext.getContext("path")

Hope you find this helpful.

Christoffer Hammarström · Accepted Answer · 2012-05-11T14:08:08.900

1

Instead of trying to find the Filter to tell it, have the Filter look the information up by querying a service somewhere (e.g. stored in the ServletContext), or just have the service store the information in the ServletContext.

edited May 11 '12 at 14:08

answered May 11 '12 at 13:58

Christoffer Hammarström

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Very cool! That is a better way of looking at it, and less hassle. Thanks. – Steve May 11 '12 at 14:15

How to access a running servlet filter?

2 Answers2