universe@6: /*
universe@6:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@6:  * 
universe@6:  * Copyright 2017 Mike Becker. All rights reserved.
universe@6:  * 
universe@6:  * Redistribution and use in source and binary forms, with or without
universe@6:  * modification, are permitted provided that the following conditions are met:
universe@6:  *
universe@6:  *   1. Redistributions of source code must retain the above copyright
universe@6:  *      notice, this list of conditions and the following disclaimer.
universe@6:  *
universe@6:  *   2. Redistributions in binary form must reproduce the above copyright
universe@6:  *      notice, this list of conditions and the following disclaimer in the
universe@6:  *      documentation and/or other materials provided with the distribution.
universe@6:  *
universe@6:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@6:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@6:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@6:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@6:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@6:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@6:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@6:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@6:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@6:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@6:  * POSSIBILITY OF SUCH DAMAGE.
universe@6:  * 
universe@6:  */
universe@6: package de.uapcore.lightpit;
universe@6: 
universe@7: import javax.servlet.Registration;
universe@6: import javax.servlet.ServletContext;
universe@6: import javax.servlet.ServletContextEvent;
universe@6: import javax.servlet.ServletContextListener;
universe@6: import javax.servlet.annotation.WebListener;
universe@8: import org.slf4j.Logger;
universe@8: import org.slf4j.LoggerFactory;
universe@6: 
universe@6: /**
universe@6:  * Scans registered servlets for LightPIT modules.
universe@6:  */
universe@6: @WebListener
universe@6: public class ModuleManager implements ServletContextListener {
universe@6:     
universe@8:     private static final Logger LOG = LoggerFactory.getLogger(ModuleManager.class);
universe@6:     
universe@6:     /**
universe@6:      * The attribute name in the servlet context under which an instance of this class can be found.
universe@6:      */
universe@6:     public static final String SC_ATTR_NAME = ModuleManager.class.getName();
universe@6:     
universe@6:     private ServletContext sc;
universe@6:     
universe@6:     @Override
universe@6:     public void contextInitialized(ServletContextEvent sce) {
universe@6:         sc = sce.getServletContext();
universe@6:         reloadAll();
universe@6:         sc.setAttribute(SC_ATTR_NAME, this);
universe@6:         LOG.info("Module manager injected into ServletContext.");
universe@6:     }
universe@6: 
universe@6:     @Override
universe@6:     public void contextDestroyed(ServletContextEvent sce) {
universe@6:         assert sc != null && sc.equals(sce.getServletContext());
universe@6:         sc.removeAttribute(SC_ATTR_NAME);
universe@6:         unloadAll();
universe@6:     }
universe@6:     
universe@7:     private boolean isRegisteredAsModule(Registration reg) {
universe@6:         try {
universe@7:             final Class scclass = Class.forName(reg.getClassName());
universe@7:             
universe@9:             final boolean lpservlet = AbstractLightPITServlet.class.isAssignableFrom(scclass);
universe@7:             final boolean lpmodule = scclass.isAnnotationPresent(LightPITModule.class);
universe@7:             
universe@7:             if (lpservlet && !lpmodule) {
universe@8:                 LOG.warn(
universe@9:                     "{} is a LightPIT Servlet but is missing the module annotation.",
universe@8:                     reg.getClassName()
universe@8:                 );
universe@7:             } else if (!lpservlet && lpmodule) {
universe@8:                 LOG.warn(
universe@9:                     "{} is annotated as a LightPIT Module but does not extend {}.",
universe@9:                     reg.getClassName(),
universe@9:                     AbstractLightPITServlet.class.getSimpleName()
universe@8:                 );
universe@7:             }
universe@7:             
universe@7:             return lpservlet && lpmodule;
universe@6:         } catch (ClassNotFoundException ex) {
universe@8:             LOG.error(
universe@9:                     "Servlet registration refers to class {} which cannot be found by the class loader (Reason: {})",
universe@9:                     reg.getClassName(),
universe@9:                     ex.getMessage()
universe@8:             );
universe@6:             return false;
universe@6:         }        
universe@6:     }
universe@6:     
universe@7:     private void handleServletRegistration(String name, Registration reg) {
universe@7:         if (isRegisteredAsModule(reg)) {
universe@8:             LOG.info("Module detected: {}", name);
universe@6:         } else {
universe@8:             LOG.debug("Servlet {} is no module, skipping.", name);
universe@6:         }
universe@6:     }
universe@6:     
universe@6:     /**
universe@6:      * Scans for modules and reloads them all.
universe@6:      */
universe@6:     public void reloadAll() {
universe@6:         sc.getServletRegistrations().forEach(this::handleServletRegistration);
universe@6:         LOG.info("Modules loaded.");
universe@6:     }
universe@6:     
universe@6:     /**
universe@6:      * Unloads all found modules.
universe@6:      */
universe@6:     public void unloadAll() {
universe@6:         LOG.info("All modules unloaded.");
universe@6:     }
universe@6: }