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Page 699 HF Servlets and JSP
Ques 5

Which about Filters is true


A. Filters may be used to create request and response wrappers.
B. Wrappers may be used to create request or reponse filters

Shouldn't B be correct instead of A
Correct Ans given in book is A
 
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I also had the same problem the first time, then I understood. Thanks to filter, it's possible to create a 'wrapper' around a request/response objects. Filters use wrappers but it's not the other way round. Think of a filter to compress the response. The filter uses the HttpServletResponseWrapper class to actually pass behind the scenes a custom response object whose getOutputStream() method returns a custom output stream in gzip format. It's the filter which knows about the wrapper and not the other way round.

Hope this helps
 
It is sorta covered in the JavaRanch Style Guide.
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