| An interface that can be implemented in order to get notifications of
objects being pushed onto a digester stack or popped from one.
Because objects are pushed onto the main object stack when a rule
has created a new object, this gives the ability to intercept such
operations and perform modifications on created objects.
One use expected for this interface is to store information about the xml
line that a particular object was created from. An implementation of this
interface can detect whenever an object is pushed onto the digester object
stack, call Digester.getDocumentLocator() to get the location within the
current xml file, and store this either on the object on the stack (if it
supports some user-specific interface for this purpose), or build a map of
(object->locationinfo) separately.
It is recommended that objects implementing this interface provide
a method to set a "next" action, and invoke it from the callback
methods. This allows multiple actions to be "chained" together.
See also Digester.setStackAction.
since:
1.8 |