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A ComponentManager
selects Component
s based on a
role. The contract is that all the Component
s implement the
differing roles and there is one Component
per role. If you
need to select on of many Component
s that implement the same
role, then you need to use a ComponentSelector
. Roles are
usually the full interface name.
A role is better understood by the analogy of a play. There are many
different roles in a script. Any actor or actress can play any given part
and you get the same results (phrases said, movements made, etc.). The exact
nuances of the performance is different.
Below is a list of things that might be considered the different roles:
ComponentManager
does not specify the methodology of
getting the Component
, merely the interface used to get it.
Therefore the ComponentManager
can be implemented with a
factory pattern, an object pool, or a simple Hashtable.
Component
,
Composable
,
ComponentSelector
Method Summary | |
boolean |
hasComponent(java.lang.String role)
Check to see if a Component exists for a role. |
Component |
lookup(java.lang.String role)
Get the Component associated with the given role. |
void |
release(Component component)
Return the Component when you are finished with it. |
Method Detail |
public Component lookup(java.lang.String role) throws ComponentException
Component
associated with the given role. For
instance, If the ComponentManager
had a
LoggerComponent
stored and referenced by role, I would use
the following call:
try { MyComponent log; myComponent = (MyComponent) manager.lookup(MyComponent.ROLE); } catch (...) { ... }
ComponentException
- if an error occurspublic boolean hasComponent(java.lang.String role)
Component
exists for a role.
role
- a string identifying the role to check.
public void release(Component component)
Component
when you are finished with it. This
allows the ComponentManager
to handle the End-Of-Life Lifecycle
events associated with the Component. Please note, that no Exceptions
should be thrown at this point. This is to allow easy use of the
ComponentManager system without having to trap Exceptions on a release.
component
- The Component we are releasing.
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