alma.acs.monitoring

Class DynamicInterceptor

java.lang.Object

alma.acs.monitoring.DynamicInterceptor

All Implemented Interfaces:

java.lang.reflect.InvocationHandler

public class DynamicInterceptor
extends java.lang.Object
implements java.lang.reflect.InvocationHandler

Dynamic interceptor, to be used for example to log or modify calls to a corba object like the CDB or a Java component.

This class has been extracted and generalized from alma.acs.container.ContainerSealant in module jcont, to allow reusing the code for intercepting other calls as well.

Since:

ACS 9.0

Author:

hsommer

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	DynamicInterceptor.InterceptionHandler Users of the DynamicInterceptor class must provide a DynamicInterceptor.InterceptionHandlerFactory which will be used to create an instance of this DynamicInterceptor.InterceptionHandler for every intercepted call.
static interface	DynamicInterceptor.InterceptionHandlerFactory We use a factory to allow for the convenient (though slightly less performant) design of grouping the methods for notification before and after the intercepted call is performed into a single dedicated DynamicInterceptor.InterceptionHandler object.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DynamicInterceptor(java.lang.Object delegate, java.util.logging.Logger logger, java.lang.ClassLoader contextCL, DynamicInterceptor.InterceptionHandlerFactory interceptionHandlerFactory) To be called only from the proxy factory method createDynamicInterceptor(Class, Object, Logger, ClassLoader, InterceptionHandlerFactory)

Method Summary

Modifier and Type	Method and Description
static <T> T	createDynamicInterceptor(java.lang.Class<T> dynInterface, java.lang.Object delegate, java.util.logging.Logger logger, java.lang.ClassLoader contextCL, DynamicInterceptor.InterceptionHandlerFactory interceptionHandlerFactory) Creates a DynamicInterceptor instance and uses it as the invocation handler for the returned dynamic proxy which implements dynInterface.
java.lang.Object	invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) Receives the intercepted calls, and forwards them to the handler and delegate object.

Methods inherited from class java.lang.Object

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

Constructor Detail

DynamicInterceptor

protected DynamicInterceptor(java.lang.Object delegate,
                             java.util.logging.Logger logger,
                             java.lang.ClassLoader contextCL,
                             DynamicInterceptor.InterceptionHandlerFactory interceptionHandlerFactory)

To be called only from the proxy factory method createDynamicInterceptor(Class, Object, Logger, ClassLoader, InterceptionHandlerFactory)

Method Detail

createDynamicInterceptor

public static <T> T createDynamicInterceptor(java.lang.Class<T> dynInterface,
                                             java.lang.Object delegate,
                                             java.util.logging.Logger logger,
                                             java.lang.ClassLoader contextCL,
                                             DynamicInterceptor.InterceptionHandlerFactory interceptionHandlerFactory)

Creates a DynamicInterceptor instance and uses it as the invocation handler for the returned dynamic proxy which implements dynInterface.

Note that if we want to allow a chain of handlers for each call, e.g. to more cleanly separate logging from permission checks, then we should change this method to accept a List<InterceptionHandlerFactory>, to create many InterceptionHandler objects for each call. These handlers must then be chained together in a way that the call aborts after the first handler's callReceived has returned false, and the return value of the first handler's callFinished is fed to the second handler as the retVal argument.

Parameters:

dynInterface -

delegate - The delegation object.
Note about usage of java generics: Ideally this delegate would be declared "T" instead of "Object", but did not get it to work with that...

logger - The Logger to be used by this class.

contextCL - The class loader to be associated with the current thread during the forwarding of the call to the delegate object, or null if the interceptor should not swap the classloader.

interceptionHandlerFactory - Will be used to create the callback object (one per invocation).

invoke

public java.lang.Object invoke(java.lang.Object proxy,
                               java.lang.reflect.Method method,
                               java.lang.Object[] args)
                        throws java.lang.Throwable

Receives the intercepted calls, and forwards them to the handler and delegate object. Also sets the class loader passed to createDynamicInterceptor(Class, Object, Logger, ClassLoader, InterceptionHandlerFactory) as the current thread's context class loader (see Thread.currentThread().getContextClassLoader()).

Specified by:

invoke in interface java.lang.reflect.InvocationHandler

Throws:

java.lang.Throwable

See Also:

InvocationHandler.invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])