org.apache.shale.tiger.view.faces.ViewControllerCallbacks2 Maven / Gradle / Ivy
The newest version!
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.shale.tiger.view.faces;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import javax.faces.context.FacesContext;
import org.apache.shale.tiger.view.Destroy;
import org.apache.shale.tiger.view.Preprocess;
import org.apache.shale.tiger.view.Prerender;
import org.apache.shale.tiger.view.View;
import org.apache.shale.view.ViewController;
import org.apache.shale.view.faces.ViewControllerCallbacks;
/**
* Utility class to perform the event callbacks specified by the
* {@link ViewController} interface. This version will call through
* to ViewController methods if the bean class actually implements this
* interface, or ituses annotations to identify the relevant methods.
*
* NOTE - The annotated callback methods must be
* public, and take no arguments. They may exist on the class of the
* instance being passed in, or be inherited from a superclass.
*
* $Id: ViewControllerCallbacks2.java 560353 2007-07-27 18:49:58Z gvanmatre $
*
* @since 1.0.1
*/
public class ViewControllerCallbacks2 extends ViewControllerCallbacks {
// ------------------------------------------------------------ Constructors
// ------------------------------------------------------ Instance Variables
// ---------------------------------------------------------- Public Methods
/**
* Perform the preprocess callback on the specified
* instance.
*
* @param instance Bean instance on which to perform this callback
*/
public void preprocess(Object instance) {
if (instance instanceof ViewController) {
try {
((ViewController) instance).preprocess();
} catch (Exception e) {
handleException(FacesContext.getCurrentInstance(), e);
}
return;
}
Method method = method(instance, Preprocess.class);
if (method != null) {
try {
method.invoke(instance, new Object[0]);
} catch (IllegalAccessException e) {
handleException(FacesContext.getCurrentInstance(), e);
} catch (InvocationTargetException e) {
handleException(FacesContext.getCurrentInstance(), (Exception) e.getCause());
}
}
}
/**
* Perform the prerender callback on the specified
* instance.
*
* @param instance Bean instance on which to perform this callback
*/
public void prerender(Object instance) {
if (instance instanceof ViewController) {
try {
((ViewController) instance).prerender();
} catch (Exception e) {
handleException(FacesContext.getCurrentInstance(), e);
}
return;
}
Method method = method(instance, Prerender.class);
if (method != null) {
try {
method.invoke(instance, new Object[0]);
} catch (IllegalAccessException e) {
handleException(FacesContext.getCurrentInstance(), e);
} catch (InvocationTargetException e) {
handleException(FacesContext.getCurrentInstance(), (Exception) e.getCause());
}
}
}
/**
* Checks the instance to determine if it is a
* shale ViewController, AbstractRequestBean,
* or has the Destory annotation.
*
* @param instance Bean instance on which to perform this callback
* @return true if the instance implements has a destroy callback
*/
public boolean isViewController(Object instance) {
if (super.isViewController(instance)) {
return true;
}
return (method(instance, Destroy.class) != null);
}
// --------------------------------------------------------- Private Methods
/**
* The set of method annotations for callbacks of interest.
*/
private static final Class[] annotations =
{ Preprocess.class, Prerender.class, Destroy.class };
/**
* Data structure to maintain information about annotated
* methods. In this map, the key is the Class being analyzed,
* and the value is an inner map. In the inner map, the key
* is an Annotation class, and the value is the corresponding
* Method instance.
*/
private transient Map> maps =
new HashMap>();
/**
* Return the Method to be called for the specified
* annotation on the specified instance, if any. If there is no such
* method, return null.
*
* @param instance Instance on which callbacks will be performed
* @param annotation Annotation for which to return a method
*/
private Method method(Object instance, Class annotation) {
// Does the underlying class implement the View annotation?
// If not, exit early
Class clazz = instance.getClass();
if (clazz.getAnnotation(View.class) == null) {
return null;
}
synchronized (maps) {
// If we have seen this Class already, simply return the
// previously located Method (if any)
Map map = maps.get(clazz);
if (map != null) {
return map.get(annotation);
}
// Construct and cache a new Map identifying the
// methods of interest for these callbacks
map = new HashMap();
Method[] methods = clazz.getMethods();
for (int i = 0; i < methods.length; i++) {
if (methods[i].getParameterTypes().length > 0) {
continue;
}
for (int j = 0; j < annotations.length; j++) {
if (methods[i].getAnnotation(annotations[j]) != null) {
map.put(annotations[j], methods[i]);
}
}
}
maps.put(clazz, map);
return map.get(annotation);
}
}
}