What code， inserted at line 21， is called prior to a session being migrated to a different JVM assuming the web application containing MyExample is deployed in a container which supports distributed applications？（）

多项选择题Whichthe threearetrueaboutservletfilters？（）

A. A filter must implement the destroy method
B. A filter must implement the doFilter method
C. A servlet may have multiple filters associated with it
D. A servlet that is to have a filter applied to it must implement the javax.servlet.FilterChain  interface
E. A filter that is part of a filter chain passes control to the next filter in the chain by invoking the filterChain forward method
F. For each  element in the web application deployment descriptor， multiple instances of a filter may be created by the web container

多项选择题Assume session is an HttpSession， and is not referenced anywhere else in ServletA. Which two changes， taken together， ensure that value is equal to “Hello” on line 23？ （）

A.A
B.B
C.C
D.D
E.E

单项选择题Given the HttpServlet code：   getServletContext（）.setAttribute（“foo”， “value”）； What is the result？（）

A. The attribute foo is placed in the application
B. A ServletContextListener registered for that servlet is notified
C. A ServletAttributeListener registered for that servlet is notified
D. An HttpSessionAttributeListener registered for that servlet is notified

单项选择题Whichisthe true choiceaboutthewebcontainerrequestprocessingmodel（）？

A. The init method on a filter is called the first time a servlet mapped to that filter is invoked
B. A filter defined for a servlet must always forward control to the next resource in the filter chain.
C. Filters associated with a named servlet are applied in the order they appear in the web application deployment descriptor file
D. If the init method on a filter throws an UnavailableException， then the container will make no further attempt to execute it

多项选择题Whichthe twoaretrueregardingawebapplicationclassloader？（）

A. A web application may override the web container’s implementation classes
B. A web application running in a J2EE product may override classes in the javax.* namespace
C. A web application class loader may NOT override any classes in the java.* and javax.*  namespace
D. Resources in the WAR class directory or in any of the JAR files within the library directory may  be accessed using the J2SE semantics of getResource
E. Resources in the WAR class directory or in any of the JAR files within the library directory  cannot be accessed using the J2SE semantics of getResource