com.mtgi.analytics.servlet.BehaviorTrackingListener.java Source code

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Here is the source code for com.mtgi.analytics.servlet.BehaviorTrackingListener.java

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/* 
 * Copyright 2008-2009 the original author or authors.
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations
 * under the License.
 */

package com.mtgi.analytics.servlet;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.servlet.FrameworkServlet;

import com.mtgi.analytics.BehaviorEvent;

/**
 * Logs behavior tracking events for incoming servlet requests.  This listener is activated by the
 * <code>bt:http-requests</code> Spring XML tag.  It is an alternative to {@link BehaviorTrackingFilter}
 * registration in <code>web.xml</code>.  BehaviorTrackingFilter is more flexible, but is slightly more
 * complex to configure.  At most one of these methods (bt:http-requests or BehaviorTrackingFilter) should
 * be used in a given application, otherwise errors will be thrown during application startup.
 */
public class BehaviorTrackingListener implements ServletRequestListener, ServletContextListener {

    private static final Log log = LogFactory.getLog(BehaviorTrackingListener.class);

    private static final String ATT_EVENTS = BehaviorTrackingListener.class.getName() + ".events";

    private ServletRequestBehaviorTrackingAdapter[] adapters = null;
    private boolean initialized = false;

    public void contextInitialized(ServletContextEvent event) {
    }

    public void contextDestroyed(ServletContextEvent event) {
        initialized = false;
        if (adapters != null) {
            log.info("BehaviorTracking for HTTP servlet requests stopped");
            adapters = null;
        }
    }

    public void requestInitialized(ServletRequestEvent event) {
        checkInit(event);
        if (adapters != null) {
            BehaviorEvent[] events = new BehaviorEvent[adapters.length];
            ServletRequest request = event.getServletRequest();
            request.setAttribute(ATT_EVENTS, events);

            for (int i = 0; i < adapters.length; ++i)
                try {
                    events[i] = adapters[i].start(request);
                } catch (Exception e) {
                    log.error("Error starting http event", e);
                }
        }
    }

    public void requestDestroyed(ServletRequestEvent event) {
        if (adapters != null) {
            ServletRequest request = event.getServletRequest();
            BehaviorEvent[] events = (BehaviorEvent[]) request.getAttribute(ATT_EVENTS);
            if (events == null) {
                log.error("no behavior events stored in the current request ("
                        + ((HttpServletRequest) request).getRequestURI());
            } else {
                request.removeAttribute(ATT_EVENTS);
                for (int i = adapters.length - 1; i >= 0; --i)
                    try {
                        adapters[i].stop(events[i]);
                    } catch (Exception e) {
                        log.error("Error stopping http event", e);
                    }
            }
        }
    }

    private synchronized void checkInit(ServletRequestEvent event) {
        if (!initialized) {

            ServletContext context = event.getServletContext();
            boolean hasFilter = BehaviorTrackingFilter.isFiltered(context);
            ArrayList<ServletRequestBehaviorTrackingAdapter> beans = new ArrayList<ServletRequestBehaviorTrackingAdapter>();

            //find registered request adapters in all mvc servlet contexts.
            for (Enumeration<?> atts = context.getAttributeNames(); atts.hasMoreElements();) {
                String name = (String) atts.nextElement();
                if (name.startsWith(FrameworkServlet.SERVLET_CONTEXT_PREFIX)) {
                    Object value = context.getAttribute(name);
                    if (value instanceof ListableBeanFactory)
                        addRequestAdapters(beans, (ListableBeanFactory) value, hasFilter);
                }
            }

            //look for shared application context, loaded by ContextLoaderListener.
            ListableBeanFactory parent = WebApplicationContextUtils.getWebApplicationContext(context);
            if (parent != null)
                addRequestAdapters(beans, parent, hasFilter);

            if (!beans.isEmpty()) {
                adapters = beans.toArray(new ServletRequestBehaviorTrackingAdapter[beans.size()]);
                log.info("BehaviorTracking for HTTP servlet requests started");
            }

            initialized = true;
        }
    }

    private static void addRequestAdapters(Collection<ServletRequestBehaviorTrackingAdapter> accum,
            ListableBeanFactory beanFactory, boolean hasFilter) {
        @SuppressWarnings("unchecked")
        Collection<ServletRequestBehaviorTrackingAdapter> beans = beanFactory
                .getBeansOfType(ServletRequestBehaviorTrackingAdapter.class, false, false).values();
        if (!beans.isEmpty()) {
            if (hasFilter)
                throw new IllegalStateException(
                        "You have configured both BehaviorTrackingFilters and BehaviorTrackingListeners in the same web application.  Only one of these methods may be used in a single application.");
            accum.addAll(beans);
        }
    }
}