Package org.rribbit.execution

Class AbstractListenerObjectExecutor

java.lang.Object

org.rribbit.execution.AbstractListenerObjectExecutor

All Implemented Interfaces:

ListenerObjectExecutor

Direct Known Subclasses:

MultiThreadedListenerObjectExecutor, SequentialListenerObjectExecutor

public abstract class AbstractListenerObjectExecutor
extends Object
implements ListenerObjectExecutor

This ListenerObjectExecutor provides a blueprint for the execution of a Collection of ListenerObjects and the processing of their results. The only thing left to implementation subclasses is to actually use the methods provided in this class to actually do the execution. The implementations can decide on, for example, sequential or multi-threaded execution of the different ListenerObjects.

Please note that this class uses the java method Method.invoke() and this method does NOT work with varargs. So, if you want to call a listener method that accepts varargs, you MUST explicitly pass an array where the varargs are expected, even if that array is empty, otherwise, the method will NOT match and will NOT be executed.

Author:

G.J. Schouten

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractListenerObjectExecutor.ExecutionResult	This class represents the outcome of the execution of a ListenerObject.
protected static class	AbstractListenerObjectExecutor.ObjectResult	This AbstractListenerObjectExecutor.ExecutionResult represents a successful invocation, along with its result.
protected static class	AbstractListenerObjectExecutor.ThrowableResult	This AbstractListenerObjectExecutor.ExecutionResult represents an unsuccessful invocation, where the method threw a Throwable.
protected static class	AbstractListenerObjectExecutor.VoidResult	This AbstractListenerObjectExecutor.ExecutionResult represents a successful invocation, but no result (method return type was 'void').

Constructor Summary

Constructors

Constructor	Description
AbstractListenerObjectExecutor()

Method Summary

Modifier and Type	Method	Description
protected abstract Collection<AbstractListenerObjectExecutor.ExecutionResult>	doExecuteListeners(Collection<ListenerObject> listenerObjects, Object... parameters)	This method should call executeSingleListenerObject(ListenerObject, Object...) on each ListenerObject, accumulate the results, and return.
<T> Response<T>	executeListeners(Collection<ListenerObject> listenerObjects, Object... parameters)	Executes all ListenerObjects in the given Collection and gives the return values back.
protected AbstractListenerObjectExecutor.ExecutionResult	executeSingleListenerObject(ListenerObject listenerObject, Object... parameters)	This method executes a single ListenerObject and returns the appropriate AbstractListenerObjectExecutor.ExecutionResult.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AbstractListenerObjectExecutor

public AbstractListenerObjectExecutor()

Method Details

executeListeners

public <T> Response<T> executeListeners(Collection<ListenerObject> listenerObjects,
 Object... parameters)

Description copied from interface: ListenerObjectExecutor

Executes all ListenerObjects in the given Collection and gives the return values back. There is no guarantee on the ordering of the results. This means that implementations can use any execution order they like.

The number of ListenerObject that are executed may be larger than the number of return values that is returned, because some ListenerObjects may return nothing (void).

Also note that some ListenerObjects in the 'listenerObjects' Collection may not match the parameters in the 'parameters' array. Implementation need to take this into account and provide proper error handling. When a ListenerObject does not match the parameter Objects, it is to be ignored and not to be incorporated into the results. Generally, the most efficient way of checking this is to just try to call invoke() on the Method of the ListenerObject. If any Exception other than InvocationTargetException occurs, it will probably mean that the parameters will not match the Method. An InvocationTargetException means that there was a successful invocation, but a Throwable was thrown from the method itself.

Specified by:

executeListeners in interface ListenerObjectExecutor

Parameters:

listenerObjects - the ListenerObjects that have to be executed

parameters - the parameters to give to the ListenerObjects

Returns:

the Response object representing the response of this execution

executeSingleListenerObject

protected AbstractListenerObjectExecutor.ExecutionResult executeSingleListenerObject(ListenerObject listenerObject,
 Object... parameters)

This method executes a single ListenerObject and returns the appropriate AbstractListenerObjectExecutor.ExecutionResult. It should be used by subclasses when excuting the ListenerObjects.

Parameters:

listenerObject -

parameters -

Returns:

the AbstractListenerObjectExecutor.ExecutionResult of the execution of the ListenerObject, or null if the ListenerObject did not match the parameters

doExecuteListeners

protected abstract Collection<AbstractListenerObjectExecutor.ExecutionResult> doExecuteListeners(Collection<ListenerObject> listenerObjects,
 Object... parameters)

This method should call executeSingleListenerObject(ListenerObject, Object...) on each ListenerObject, accumulate the results, and return. Typical implementations do this either sequentially, or multi-threaded.

Parameters:

listenerObjects -

parameters -

Returns:

a Collection with the AbstractListenerObjectExecutor.ExecutionResults of the given ListenerObjects or an empty Collection if there are no results, never returns null