LightPIT: src/java/de/uapcore/lightpit/ModuleManager.java@20a9b2bc9063

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2017 Mike Becker. All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  *

    28  */

    29 package de.uapcore.lightpit;

    31 import javax.servlet.Registration;

    32 import javax.servlet.ServletContext;

    33 import javax.servlet.ServletContextEvent;

    34 import javax.servlet.ServletContextListener;

    35 import javax.servlet.annotation.WebListener;

    36 import org.slf4j.Logger;

    37 import org.slf4j.LoggerFactory;

    39 /**

    40  * Scans registered servlets for LightPIT modules.

    41  */

    42 @WebListener

    43 public class ModuleManager implements ServletContextListener {

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

    47     /**

    48      * The attribute name in the servlet context under which an instance of this class can be found.

    49      */

    50     public static final String SC_ATTR_NAME = ModuleManager.class.getName();

    52     private ServletContext sc;

    54     @Override

    55     public void contextInitialized(ServletContextEvent sce) {

    56         sc = sce.getServletContext();

    57         reloadAll();

    58         sc.setAttribute(SC_ATTR_NAME, this);

    59         LOG.info("Module manager injected into ServletContext.");

    60     }

    62     @Override

    63     public void contextDestroyed(ServletContextEvent sce) {

    64         assert sc != null && sc.equals(sce.getServletContext());

    65         sc.removeAttribute(SC_ATTR_NAME);

    66         unloadAll();

    67     }

    69     private boolean isRegisteredAsModule(Registration reg) {

    70         try {

    71             final Class scclass = Class.forName(reg.getClassName());

    73             final boolean lpservlet = AbstractLightPITServlet.class.isAssignableFrom(scclass);

    74             final boolean lpmodule = scclass.isAnnotationPresent(LightPITModule.class);

    76             if (lpservlet && !lpmodule) {

    77                 LOG.warn(

    78                     "{} is a LightPIT Servlet but is missing the module annotation.",

    79                     reg.getClassName()

    80                 );

    81             } else if (!lpservlet && lpmodule) {

    82                 LOG.warn(

    83                     "{} is annotated as a LightPIT Module but does not extend {}.",

    84                     reg.getClassName(),

    85                     AbstractLightPITServlet.class.getSimpleName()

    86                 );

    87             }

    89             return lpservlet && lpmodule;

    90         } catch (ClassNotFoundException ex) {

    91             LOG.error(

    92                     "Servlet registration refers to class {} which cannot be found by the class loader (Reason: {})",

    93                     reg.getClassName(),

    94                     ex.getMessage()

    95             );

    96             return false;

    97         }

    98     }

   100     private void handleServletRegistration(String name, Registration reg) {

   101         if (isRegisteredAsModule(reg)) {

   102             LOG.info("Module detected: {}", name);

   103         } else {

   104             LOG.debug("Servlet {} is no module, skipping.", name);

   105         }

   106     }

   108     /**

   109      * Scans for modules and reloads them all.

   110      */

   111     public void reloadAll() {

   112         sc.getServletRegistrations().forEach(this::handleServletRegistration);

   113         LOG.info("Modules loaded.");

   114     }

   116     /**

   117      * Unloads all found modules.

   118      */

   119     public void unloadAll() {

   120         LOG.info("All modules unloaded.");

   121     }

   122 }

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