/*
* Copyright (c) 1999-2004 Sourceforge JACOB Project.
* All rights reserved. Originator: Dan Adler (http://danadler.com).
* Get more information about JACOB at http://sourceforge.net/projects/jacob-project
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.jacob.com;
/**
* @version $Id$
* @author joe
*
* DispatchEvents wraps this class around any event handlers before making the
* JNI call that sets up the link with EventProxy. This means that
* EventProxy.cpp just calls invoke(String,Variant[]) against the instance of
* this class. Then this class does reflection against the event listener to
* call the actual event methods. The event methods can return void or return a
* Variant. Any value returned will be passed back to the calling windows module
* by the Jacob JNI layer.
* <p>
*
* The void returning signature is the standard legacy signature. The Variant
* returning signature was added in 1.10 to support event handlers returning
* values.
*
*/
public abstract class InvocationProxy {
/**
* the object we will try and forward to.
*/
protected Object mTargetObject = null;
/**
* dummy constructor for subclasses that don't actually wrap anything and
* just want to override the invoke() method
*/
protected InvocationProxy() {
super();
}
/**
* The method actually invoked by EventProxy.cpp. The method name is
* calculated by the underlying JNI code from the MS windows Callback
* function name. The method is assumed to take an array of Variant objects.
* The method may return a Variant or be a void. Those are the only two
* options that will not blow up.
* <p>
* Subclasses that override this should make sure mTargetObject is not null
* before processing.
*
* @param methodName
* name of method in mTargetObject we will invoke
* @param targetParameters
* Variant[] that is the single parameter to the method
* @return an object that will be returned to the com event caller
*/
public abstract Variant invoke(String methodName,
Variant targetParameters[]);
/**
* used by EventProxy.cpp to create variant objects in the right thread
*
* @return Variant object that will be used by the COM layer
*/
public Variant getVariant() {
return new VariantViaEvent();
}
/**
* Sets the target for this InvocationProxy.
*
* @param pTargetObject
* @throws IllegalArgumentException
* if target is not publicly accessible
*/
public void setTarget(Object pTargetObject) {
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("InvocationProxy: setting target "
+ pTargetObject);
}
if (pTargetObject != null) {
// JNI code apparently bypasses this check and could operate against
// protected classes. This seems like a security issue...
// maybe it was because JNI code isn't in a package?
if (!java.lang.reflect.Modifier.isPublic(pTargetObject.getClass()
.getModifiers())) {
throw new IllegalArgumentException(
"InvocationProxy only public classes can receive event notifications");
}
}
mTargetObject = pTargetObject;
}
}
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