Sun, 17 Dec 2017 01:45:28 +0100
implements simple request mapper
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 java.util.ArrayList;
32 import java.util.Collections;
33 import java.util.List;
34 import java.util.Optional;
35 import javax.servlet.Registration;
36 import javax.servlet.ServletContext;
37 import javax.servlet.ServletContextEvent;
38 import javax.servlet.ServletContextListener;
39 import javax.servlet.annotation.WebListener;
40 import org.slf4j.Logger;
41 import org.slf4j.LoggerFactory;
43 /**
44 * Scans registered servlets for LightPIT modules.
45 */
46 @WebListener
47 public final class ModuleManager implements ServletContextListener {
49 private static final Logger LOG = LoggerFactory.getLogger(ModuleManager.class);
51 /**
52 * The attribute name in the servlet context under which an instance of this class can be found.
53 */
54 public static final String SC_ATTR_NAME = ModuleManager.class.getName();
55 private ServletContext sc;
57 private final List<Menu> mainMenu = new ArrayList<>();
58 private final List<Menu> immutableMainMenu = Collections.unmodifiableList(mainMenu);
60 @Override
61 public void contextInitialized(ServletContextEvent sce) {
62 sc = sce.getServletContext();
63 reloadAll();
64 sc.setAttribute(SC_ATTR_NAME, this);
65 LOG.info("Module manager injected into ServletContext.");
66 }
68 @Override
69 public void contextDestroyed(ServletContextEvent sce) {
70 unloadAll();
71 }
73 private Optional<LightPITModule> getModuleInfo(Registration reg) {
74 try {
75 final Class scclass = Class.forName(reg.getClassName());
77 final boolean lpservlet = AbstractLightPITServlet.class.isAssignableFrom(scclass);
78 final boolean lpmodule = scclass.isAnnotationPresent(LightPITModule.class);
80 if (lpservlet && !lpmodule) {
81 LOG.warn(
82 "{} is a LightPIT Servlet but is missing the module annotation.",
83 reg.getClassName()
84 );
85 } else if (!lpservlet && lpmodule) {
86 LOG.warn(
87 "{} is annotated as a LightPIT Module but does not extend {}.",
88 reg.getClassName(),
89 AbstractLightPITServlet.class.getSimpleName()
90 );
91 }
93 if (lpservlet && lpmodule) {
94 final Class<? extends AbstractLightPITServlet> clazz = scclass;
95 final LightPITModule moduleInfo = clazz.getAnnotation(LightPITModule.class);
96 return Optional.of(moduleInfo);
97 } else {
98 return Optional.empty();
99 }
100 } catch (ClassNotFoundException ex) {
101 LOG.error(
102 "Servlet registration refers to class {} which cannot be found by the class loader (Reason: {})",
103 reg.getClassName(),
104 ex.getMessage()
105 );
106 return Optional.empty();
107 }
108 }
110 private void addModuleToMenu(String moduleClassName, LightPITModule moduleInfo) {
111 final Menu menu = new Menu(
112 moduleClassName,
113 new ResourceKey(moduleInfo.bundleBaseName(), moduleInfo.menuKey()),
114 moduleInfo.modulePath()
115 );
116 mainMenu.add(menu);
117 }
119 private void handleServletRegistration(String name, Registration reg) {
120 final Optional<LightPITModule> moduleInfo = getModuleInfo(reg);
121 if (moduleInfo.isPresent()) {
123 // TODO: remove this call and add the module to some dependency resolver, first
124 addModuleToMenu(reg.getClassName(), moduleInfo.get());
126 LOG.info("Module detected: {}", name);
127 } else {
128 LOG.debug("Servlet {} is no module, skipping.", name);
129 }
130 }
132 /**
133 * Scans for modules and reloads them all.
134 */
135 public void reloadAll() {
136 sc.getServletRegistrations().forEach(this::handleServletRegistration);
137 LOG.info("Modules loaded.");
138 }
140 /**
141 * Unloads all found modules.
142 */
143 public void unloadAll() {
144 mainMenu.clear();
145 LOG.info("All modules unloaded.");
146 }
148 /**
149 * Returns the main menu.
150 * @return a list of menus belonging to the main menu
151 */
152 public List<Menu> getMainMenu() {
153 return immutableMainMenu;
154 }
155 }