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EPractice mock quiz 1

 
Himai Minh
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You want to create a filter for your web application and your filter will implement javax.servlet.Filter.
Which two statements are true?
[ Choose two ]

a. Your filter class must implement an init method and a destroy method.
b. Your filter class must also implement javax.servlet.FilterChain.
c. When your filter chains to the next filter, it should pass the same arguments it received in its doFilter method.
d. The method that your filter invokes on the object it received that implements javax.servlet.FilterChain can invoke either another filter or a servlet.
e. Your filter class must implement a doFilter method that takes, among other things, an HTTPServletRequest object and an HTTPServletResponse object.

Explanation:
Choice A and Choice D are correct

A filter is an object that performs filtering tasks on either the request to a resource (a servlet or static content), or on the response from a resource, or both.
Filters perform filtering in the doFilter method. Every Filter has access to a FilterConfig object from which it can obtain its initialization parameters, and a reference to the ServletContext which it can use, for example, to load resources needed for filtering tasks.
Filters are configured in the deployment descriptor of a web application.
Examples that have been identified for this design are:
1. Authentication Filters
2. Logging and Auditing Filters
3. Image conversion Filters
4. Data compression Filters
5. Encryption Filters
6. Tokenizing Filters
7. Filters that trigger resource access events
8. XSL/T filters
9. Mime-type chain Filter
A FilterChain is an object provided by the servlet container to the developer giving a view into the invocation chain of a filtered request for a resource. Filters use the FilterChain to invoke the next filter in the chain, or if the calling filter is the last filter in the chain, to invoke the resource at the end of the chain.
Your filter class must implement an init method and a destroy method.
The method that your filter invokes on the object it received that implements javax.servlet.FilterChain can invoke either another filter or a servlet.


I think C is an option too.
For example:

The FilterChain chain object calls doFilter that takes request and response objects, which are the same object from the doFilter method of the Filter.
Reference:
http://www.tutorialspoint.com/servlets/servlets-writing-filters.htm
 
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