org.axonframework.common.annotation

Class AbstractMessageHandler

java.lang.Object

org.axonframework.common.annotation.AbstractMessageHandler

All Implemented Interfaces:

Comparable<AbstractMessageHandler>

Direct Known Subclasses:

ConstructorCommandMessageHandler, MethodMessageHandler

public abstract class AbstractMessageHandler
extends Object
implements Comparable<AbstractMessageHandler>

Abstract superclass for annotation based Message handlers. Handlers can be compared with on another to decide upon their priority. Handlers that deal with unrelated payloads (i.e. have no parent-child relationship) are ordered based on their payload type's class name.

Handler invokers should always evaluate the first (smallest) suitable handler before evaluating the next.

Since:

2.0

Author:

Allard Buijze

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMessageHandler(AbstractMessageHandler delegate) Constructor used for implementations that delegate activity to another handler.
protected	AbstractMessageHandler(Class<?> payloadType, Class<?> declaringClass, ParameterResolver... parameterValueResolvers) Initializes the MessageHandler to handle messages with the given payloadType, declared in the given declaringClass and using the given parameterValueResolvers.

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(AbstractMessageHandler o)
boolean	equals(Object obj)
protected static ParameterResolver[]	findResolvers(ParameterResolverFactory parameterResolverFactory, Annotation[] memberAnnotations, Class<?>[] parameterTypes, Annotation[][] parameterAnnotations, boolean resolvePayload) Finds ParameterResolvers for the given Member details.
abstract <T extends Annotation> T	getAnnotation(Class<T> annotationType) Returns the member-level annotation of given annotationType, or null if no such annotation is present.
protected ParameterResolver[]	getParameterValueResolvers() Returns the parameter resolvers provided at construction time.
Class	getPayloadType() Returns the type of payload this handler expects.
int	hashCode()
abstract Object	invoke(Object target, Message message) Invokes this handler for the given target instance, using the given message as source object to provide parameter values.
boolean	matches(Message message) Indicates whether this Handler is suitable for the given message.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractMessageHandler

protected AbstractMessageHandler(Class<?> payloadType,
                      Class<?> declaringClass,
                      ParameterResolver... parameterValueResolvers)

Initializes the MessageHandler to handle messages with the given payloadType, declared in the given declaringClass and using the given parameterValueResolvers.

Parameters:

payloadType - The type of payload this handlers deals with

declaringClass - The class on which the handler is declared

parameterValueResolvers - The resolvers for each of the handlers' parameters

AbstractMessageHandler

protected AbstractMessageHandler(AbstractMessageHandler delegate)

Constructor used for implementations that delegate activity to another handler. Required information is gathered from the target handler.

Parameters:

delegate - The handler to which actual invocations are being forwarded

Method Detail

matches

public boolean matches(Message message)

Indicates whether this Handler is suitable for the given message.

Parameters:

message - The message to inspect

Returns:

true if this handler can handle the message, otherwise false.

invoke

public abstract Object invoke(Object target,
            Message message)
                       throws InvocationTargetException,
                              IllegalAccessException

Invokes this handler for the given target instance, using the given message as source object to provide parameter values.

Parameters:

target - The target instance to invoke the Handler on.

message - The message providing parameter values

Returns:

The result of the handler invocation

Throws:

InvocationTargetException - when the handler throws a checked exception

IllegalAccessException - if the SecurityManager refuses the handler invocation

getPayloadType

public Class getPayloadType()

Returns the type of payload this handler expects.

Returns:

the type of payload this handler expects

compareTo

public int compareTo(AbstractMessageHandler o)

Specified by:

compareTo in interface Comparable<AbstractMessageHandler>

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

findResolvers

protected static ParameterResolver[] findResolvers(ParameterResolverFactory parameterResolverFactory,
                                Annotation[] memberAnnotations,
                                Class<?>[] parameterTypes,
                                Annotation[][] parameterAnnotations,
                                boolean resolvePayload)

Finds ParameterResolvers for the given Member details. The returning array contains as many elements as the given parameterTypes, where each ParameterResolver corresponds with the parameter type at the same location.

Parameters:

parameterResolverFactory - The factory to create the ParameterResolvers with

memberAnnotations - The annotations on the member (e.g. method)

parameterTypes - The parameter type of the member

parameterAnnotations - The annotations on each of the parameters

resolvePayload - Indicates whether the payload of the message should be resolved from the parameters

Returns:

the parameter resolvers for the given Member details

See Also:

Method, Constructor

getParameterValueResolvers

protected ParameterResolver[] getParameterValueResolvers()

Returns the parameter resolvers provided at construction time.

Returns:

the parameter resolvers provided at construction time

getAnnotation

public abstract <T extends Annotation> T getAnnotation(Class<T> annotationType)

Returns the member-level annotation of given annotationType, or null if no such annotation is present.

Type Parameters:

T - The type of annotation to retrieve

Parameters:

annotationType - The type of annotation to retrieve

Returns:

the annotation instance, or null if no such annotation is present.