dinistiq.web.DinistiqContextLoaderListener.java Source code

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Here is the source code for dinistiq.web.DinistiqContextLoaderListener.java

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/**
 *
 * Copyright 2013-2015 Martin Goellnitz
 *
 * This program 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 program. If not, see <http://www.gnu.org/licenses/>.
 *
 */
package dinistiq.web;

import dinistiq.ClassResolver;
import dinistiq.Dinistiq;
import dinistiq.SimpleClassResolver;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRegistration;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Context loader listener to initialize the context with a dinistiq instance.
 *
 * A dinistiq.packages init param will be necessary to find application specific components.
 *
 * The instance is stored in a servlet context attribute for later use together with all the other bean definitions
 * from the dinistiq scope.
 */
public class DinistiqContextLoaderListener implements ServletContextListener {

    private static final Logger LOG = LoggerFactory.getLogger(DinistiqContextLoaderListener.class);

    /**
     * Attribute name for the context/application scope to store the dinistiq instance.
     */
    public static final String DINISTIQ_INSTANCE = "DINISTIQ_INSTANCE";

    /**
     * Init parameter name for the parameter holding the list of packages to scan for annotations.
     */
    public static final String DINISTIQ_PACKAGES = "dinistiq.packages";

    /**
     * Init parameter name for the parameter holding class resolver name.
     */
    public static final String DINISTIQ_CLASSRESOLVER = "dinistiq.class.resolver";

    /**
     * Web related dinistiq initialization with parameters taken from the web.xml.
     *
     * Looks up relevant packages for scanning and a custom class resolver's implementation class name. Exposes any
     * bean from the dinistiq scope to the application scope (servlet context) of the web layer including an instance
     * of dinistiq itself.
     *
     * @param contextEvent
     */
    @Override
    public void contextInitialized(ServletContextEvent contextEvent) {
        // just to check what our log instance looks like
        LOG.warn("contextInitialized() log: {}", LOG.getClass().getName());
        ServletContext context = contextEvent.getServletContext();
        Set<String> packages = new HashSet<>();
        String packagNameString = context.getInitParameter(DINISTIQ_PACKAGES);
        if (StringUtils.isNotBlank(packagNameString)) {
            for (String packageName : packagNameString.split(",")) {
                packageName = packageName.trim();
                packages.add(packageName);
            } // for
        } // if
        String classResolverName = context.getInitParameter(DINISTIQ_CLASSRESOLVER);
        ClassResolver classResolver = null;
        if (StringUtils.isNotBlank(classResolverName)) {
            try {
                Class<?> forName = Class.forName(classResolverName);
                Object[] args = new Object[1];
                args[0] = packages;
                classResolver = (ClassResolver) forName.getConstructors()[0].newInstance(args);
            } catch (Exception e) {
                LOG.error("contextInitialized() cannot obtain custom class resolver", e);
            } // try/catch
        } // if
        LOG.info("contextInitialized() classResolver: {} :{}", classResolver, classResolverName);
        classResolver = (classResolver == null) ? new SimpleClassResolver(packages) : classResolver;
        try {
            Map<String, Object> externalBeans = new HashMap<>();
            externalBeans.put("servletContext", context);
            Dinistiq dinistiq = new Dinistiq(classResolver, externalBeans);
            context.setAttribute(DINISTIQ_INSTANCE, dinistiq);
            for (String name : dinistiq.getAllBeanNames()) {
                context.setAttribute(name, dinistiq.findBean(Object.class, name));
            } // for
            Collection<RegisterableServlet> servlets = dinistiq.findBeans(RegisterableServlet.class);
            List<RegisterableServlet> orderedServlets = new ArrayList<>(servlets.size());
            orderedServlets.addAll(servlets);
            Collections.sort(orderedServlets);
            LOG.debug("contextInitialized() servlets {}", orderedServlets);
            for (RegisterableServlet servlet : orderedServlets) {
                ServletRegistration registration = context.addServlet(servlet.getClass().getSimpleName(), servlet);
                for (String urlPattern : servlet.getUrlPatterns()) {
                    LOG.debug("contextInitialized() * {}", urlPattern);
                    registration.addMapping(urlPattern);
                } // for
            } // for
        } catch (Exception ex) {
            LOG.error("init()", ex);
        } // try/catch
    } // contextInitialized()

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        // Nothing to be cleaned up on context destruction
    } // contextDestroyed()

} // DinistiqContextLoaderListener