• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Filter are not Wrappers! ... or are they?

 
Ranch Hand
Posts: 128
Android Eclipse IDE Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I'm a little confused by the answer to a mock exam question in the K&B book on page 735 question 5.

The question is ...
"Filters may be used to create request or response wrappers?" ... I would think this is false since the API provides classes like HttpServletRequestWrapper etc. ... that 'wrap' (aka .. 'decorator' pattern) Servlet requests and responses. Of course one can write their ones own implementation of the ServletRequest and ServletResponse interfaces. Yet in either case theses wrappers are not Filters! And implementations of the Filter interface are not wrappers!

Am I missing something here? .. or .. Is the book incorrect?
 
Marshal
Posts: 28177
95
Eclipse IDE Firefox Browser MySQL Database
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
It's true that Filters are not Wrappers (the title of your post).

But the question doesn't ask whether Filters are Wrappers. Read it again. It asks whether Filters can create Wrappers. You point to examples of Wrappers as evidence that Filters are not Wrappers. Well, that's correct but it wasn't the question. Could a Filter create one of those Wrappers? Of course it could.
 
Keith Flo
Ranch Hand
Posts: 128
Android Eclipse IDE Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Paul,

Could a Filter create one of those Wrappers? Of course it could.



The difference seems so subtle ... as to be nearly impossible to distinguish a difference .... however, I 'll keep this in mind as i prepare for the test. I'd like to get even this kind of question right!
 
reply
    Bookmark Topic Watch Topic
  • New Topic