diff -r 131903fc16b8 -r da61a1646eba src/java/de/uapcore/lightpit/ModuleManager.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/java/de/uapcore/lightpit/ModuleManager.java Sun Nov 26 18:09:23 2017 +0100 @@ -0,0 +1,103 @@ +/* + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. + * + * Copyright 2017 Mike Becker. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + */ +package de.uapcore.lightpit; + +import java.util.logging.Level; +import java.util.logging.Logger; +import javax.servlet.ServletContext; +import javax.servlet.ServletContextEvent; +import javax.servlet.ServletContextListener; +import javax.servlet.ServletRegistration; +import javax.servlet.annotation.WebListener; + +/** + * Scans registered servlets for LightPIT modules. + */ +@WebListener +public class ModuleManager implements ServletContextListener { + + private static final Logger LOG = Logger.getLogger(ModuleManager.class.getName()); + + /** + * The attribute name in the servlet context under which an instance of this class can be found. + */ + public static final String SC_ATTR_NAME = ModuleManager.class.getName(); + + private ServletContext sc; + + @Override + public void contextInitialized(ServletContextEvent sce) { + sc = sce.getServletContext(); + reloadAll(); + sc.setAttribute(SC_ATTR_NAME, this); + LOG.info("Module manager injected into ServletContext."); + } + + @Override + public void contextDestroyed(ServletContextEvent sce) { + assert sc != null && sc.equals(sce.getServletContext()); + sc.removeAttribute(SC_ATTR_NAME); + unloadAll(); + } + + private boolean isRegisteredAsModule(ServletRegistration sr) { + try { + final Class scclass = Class.forName(sr.getClassName()); + return scclass.isAnnotationPresent(LightPITModule.class); + } catch (ClassNotFoundException ex) { + LOG.log(Level.SEVERE, + "Servlet registration refers to a class which cannot be found by the class loader: {0}", + sr.getClassName()); + return false; + } + } + + private void handleServletRegistration(String name, ServletRegistration sr) { + if (isRegisteredAsModule(sr)) { + LOG.log(Level.CONFIG, "Module detected: {0}", name); + } else { + LOG.log(Level.FINE, "Servlet {0} is no module, skipping.", name); + } + } + + /** + * Scans for modules and reloads them all. + */ + public void reloadAll() { + sc.getServletRegistrations().forEach(this::handleServletRegistration); + LOG.info("Modules loaded."); + } + + /** + * Unloads all found modules. + */ + public void unloadAll() { + LOG.info("All modules unloaded."); + } +}