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

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