uk.ac.starlink.util
Class MultiplexInvocationHandler<T>

java.lang.Object
  extended by uk.ac.starlink.util.MultiplexInvocationHandler<T>
All Implemented Interfaces:
java.lang.reflect.InvocationHandler

public class MultiplexInvocationHandler<T>
extends java.lang.Object
implements java.lang.reflect.InvocationHandler

Used to generate a proxy instance which implements a given interface and delegates its calls to each of a given list of target implementations. The content of the list of targets may be changed during the lifetime of this object, but it's not a good idea to do it while a method is being invoked.

Since:
6 Jul 2011

Constructor Summary
MultiplexInvocationHandler(T[] targets)
          Constructor.
 
Method Summary
 T createMultiplexer(java.lang.Class<T> clazz)
          Returns a new proxy instance which implements the given interface type, and which uses this handler to execute its methods.
 T[] getTargets()
          Returns the list of delegate implementations.
 java.lang.Object invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)
          Invokes a method by invoking the same method on each of this handler's target instances.
 void setTargets(T[] targets)
          Sets the list of delegate implementations.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MultiplexInvocationHandler

public MultiplexInvocationHandler(T[] targets)
Constructor.

Parameters:
targets - target instances
Method Detail

setTargets

public void setTargets(T[] targets)
Sets the list of delegate implementations.

Parameters:
targets - target instances

getTargets

public T[] getTargets()
Returns the list of delegate implementations.

Returns:
target instances

invoke

public java.lang.Object invoke(java.lang.Object proxy,
                               java.lang.reflect.Method method,
                               java.lang.Object[] args)
                        throws java.lang.Throwable
Invokes a method by invoking the same method on each of this handler's target instances. If any invocation throws an exception, it is thrown from this method and the method is not invoked on later targets. If the method terminates normally, the return value is the return value of the invocation from the first target.

Specified by:
invoke in interface java.lang.reflect.InvocationHandler
Throws:
java.lang.Throwable

createMultiplexer

public T createMultiplexer(java.lang.Class<T> clazz)
Returns a new proxy instance which implements the given interface type, and which uses this handler to execute its methods.

Parameters:
clazz - interface the return value will implement
Returns:
multiplexing proxy instance