Called by the servlet container to allow the servlet to respond to
This method is only called after the servlet's init()
method has completed successfully.
The status code of the response always should be set for a servlet
that throws or sends an error.
Servlets typically run inside multithreaded servlet containers
that can handle multiple requests concurrently. Developers must
be aware to synchronize access to any shared resources such as files,
network connections, and as well as the servlet's class and instance
More information on multithreaded programming in Java is available in
the Java tutorial on multi-threaded programming.
Called by the servlet container to indicate to a servlet that the
servlet is being taken out of service. This method is
only called once all threads within the servlet's
service method have exited or after a timeout
period has passed. After the servlet container calls this
method, it will not call the service method again
on this servlet.
This method gives the servlet an opportunity
to clean up any resources that are being held (for example, memory,
file handles, threads) and make sure that any persistent state is
synchronized with the servlet's current state in memory.