org.apache.felix.ipojo/src/main/java/org/apache/felix/ipojo/handlers/lifecycle/callback/LifecycleCallbackHandler.java

/*
 *   Copyright 2006 The Apache Software Foundation
 *
 *   Licensed 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.felix.ipojo.handlers.lifecycle.callback;

import java.lang.reflect.InvocationTargetException;
import java.util.logging.Level;

import org.apache.felix.ipojo.ComponentManager;
import org.apache.felix.ipojo.Handler;
import org.apache.felix.ipojo.Activator;
import org.apache.felix.ipojo.metadata.Element;

/**
 * Lifecycle callback handler.
 * @author Clement Escoffier
 */
public class LifecycleCallbackHandler implements Handler {

	/**
	 * The list of the callback of the component.
	 */
	private LifecycleCallback[] m_callbacks = new LifecycleCallback[0];

	/**
	 * State of the component manager (unresolved at the beginning).
	 */
	private int m_state = ComponentManager.INVALID;

	/**
	 * The component manager.
	 */
	private ComponentManager m_componentManager;

	 /**
     * Add the given Hook to the hook list.
     * @param hk : the element to add
     */
    private void addCallback(LifecycleCallback hk) {
        for (int i = 0; (m_callbacks != null) && (i < m_callbacks.length); i++) {
            if (m_callbacks[i] == hk) { return; }
        }

        if (m_callbacks.length > 0) {
            LifecycleCallback[] newHk = new LifecycleCallback[m_callbacks.length + 1];
            System.arraycopy(m_callbacks, 0, newHk, 0, m_callbacks.length);
            newHk[m_callbacks.length] = hk;
            m_callbacks = newHk;
        }
        else {
        	m_callbacks = new LifecycleCallback[] {hk};
        }

    }

	/**
	 * @see org.apache.felix.ipojo.Handler#configure(org.apache.felix.ipojo.ComponentManager, org.apache.felix.ipojo.metadata.Element)
	 */
	public void configure(ComponentManager cm, Element metadata) {
		m_componentManager = cm;
		m_callbacks = new LifecycleCallback[0];

		Element[] hooksMetadata = metadata.getElements("callback");
		for (int i = 0; i < hooksMetadata.length; i++) {
			// Create an HookMetadata object
			String initialState = hooksMetadata[i].getAttribute("initial");
			String finalState = hooksMetadata[i].getAttribute("final");
			String method = hooksMetadata[i].getAttribute("method");
			boolean isStatic = false;
			if (hooksMetadata[i].containsAttribute("isStatic") && hooksMetadata[i].getAttribute("isStatic").equals("true")) { isStatic = true; }

			LifecycleCallbackMetadata hm = new LifecycleCallbackMetadata(initialState, finalState, method, isStatic);

			LifecycleCallback hk = new LifecycleCallback(this, hm);
			addCallback(hk);
		}
		if (m_callbacks.length > 0) { m_componentManager.register(this); }
	}

	/**
	 * @see org.apache.felix.ipojo.Handler#stop()
	 */
	public void stop() {
		m_state = ComponentManager.INVALID;
	}

	/**
	 * @see org.apache.felix.ipojo.Handler#start()
	 */
	public void start() {
		Activator.getLogger().log(Level.INFO, "[" + m_componentManager.getComponentMetatada().getClassName() + "] Start the life cycle callback handler");
	}

	/**
	 * Do nothing.
	 * @see org.apache.felix.ipojo.Handler#setterCallback(java.lang.String, java.lang.Object)
	 */
	public void setterCallback(String fieldName, Object value) {
		// Do nothing
	}

	/**
	 * Do nothing, return the initial value.
	 * @see org.apache.felix.ipojo.Handler#getterCallback(java.lang.String, java.lang.Object)
	 */
	public Object getterCallback(String fieldName, Object value) {
		return value;
	}

	/**
	 * Return true.
	 * @see org.apache.felix.ipojo.Handler#isValid()
	 */
	public boolean isValid() {
		return true;
	}

	/**
	 * @return the component manager
	 */
	protected ComponentManager getComponentManager() { return m_componentManager; }

	/**
	 * When the state change call the associated hooks.
	 * @see org.apache.felix.ipojo.Handler#stateChanged(int)
	 */
	public void stateChanged(int state) {
		Activator.getLogger().log(Level.INFO, "[" + m_componentManager.getComponentMetatada().getClassName() + "] State changed in callback handler, check " + m_callbacks.length + " callbacks. Transition : " + m_state + " -> " + state);
		for (int i = 0; i < m_callbacks.length; i++) {
			if (m_callbacks[i].getMetadata().getInitialState() == m_state && m_callbacks[i].getMetadata().getFinalState() == state) {
				try {
					Activator.getLogger().log(Level.INFO, "[" + m_componentManager.getComponentMetatada().getClassName() + "] Call the callback : " + m_callbacks[i].getMetadata().getMethod());
					m_callbacks[i].call();
				} catch (NoSuchMethodException e) {
					Activator.getLogger().log(Level.SEVERE, "[" + m_componentManager.getComponentMetatada().getClassName() + "] The callback method " + m_callbacks[i].getMetadata().getMethod() + " is not found : " + e.getMessage());
				} catch (IllegalAccessException e) {
					Activator.getLogger().log(Level.SEVERE, "[" + m_componentManager.getComponentMetatada().getClassName() + "] The callback method " + m_callbacks[i].getMetadata().getMethod() + " is not accessible : " + e.getMessage());
				} catch (InvocationTargetException e) {
					Activator.getLogger().log(Level.SEVERE, "[" + m_componentManager.getComponentMetatada().getClassName() + "] The callback method " + m_callbacks[i].getMetadata().getMethod() + " has throws an exception : " + e.getMessage() + " -> " + e.getCause());
				}
			}
		}
		// Update to internal state
		m_state = state;
	}

}