net.engio.mbassy.listener

Annotation Type Handler

@Retention(value=RUNTIME)
@Inherited
@Target(value={METHOD,ANNOTATION_TYPE})
public @interface Handler

Mark any method of any class(=listener) as a message handler and configure the handler using different properties.

Author:

bennidi Date: 2/8/12

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	condition Defines a filter condition as Expression Language.
Invoke	delivery Define the mode in which a message is delivered to each listener.
boolean	enabled Enable or disable the handler.
Filter[]	filters Add any numbers of filters to the handler.
Class<? extends HandlerInvocation>	invocation Each handler call is implemented as an invocation object that implements the invocation mechanism.
int	priority Handlers are ordered by priority and handlers with higher priority are processed before those with lower priority, i.e.
boolean	rejectSubtypes Define whether or not the handler accepts sub types of the message type it declares in its signature.

Element Detail

filters

public abstract Filter[] filters

Add any numbers of filters to the handler. All filters are evaluated before the handler is actually invoked, which is only if all the filters accept the message.

Default:

{}

condition

public abstract String condition

Defines a filter condition as Expression Language. This can be used to filter the events based on attributes of the event object. Note that the expression must resolve to either true to allow the event or false to block it from delivery to the handler. The message itself is available as "msg" variable.

Returns:

the condition in EL syntax.

Default:

""

delivery

public abstract Invoke delivery

Define the mode in which a message is delivered to each listener. Listeners can be notified sequentially or concurrently.

Default:

net.engio.mbassy.listener.Invoke.Synchronously

priority

public abstract int priority

Handlers are ordered by priority and handlers with higher priority are processed before those with lower priority, i.e. Influence the order in which different handlers that consume the same message type are invoked.

Default:

0

rejectSubtypes

public abstract boolean rejectSubtypes

Define whether or not the handler accepts sub types of the message type it declares in its signature.

Default:

false

enabled

public abstract boolean enabled

Enable or disable the handler. Disabled handlers do not receive any messages. This property is useful for quick changes in configuration and necessary to disable handlers that have been declared by a superclass but do not apply to the subclass

Default:

true

invocation

public abstract Class<? extends HandlerInvocation> invocation

Each handler call is implemented as an invocation object that implements the invocation mechanism. The basic implementation uses reflection and is the default. It is possible though to provide a custom invocation to add additional logic. Note: Providing a custom invocation will most likely reduce performance, since the JIT-Compiler can not do some of its sophisticated byte code optimizations.

Default:

net.engio.mbassy.dispatch.ReflectiveHandlerInvocation.class