src/java/de/uapcore/lightpit/AbstractLightPITServlet.java@bd1a76c91d5b
src/java/de/uapcore/lightpit/AbstractLightPITServlet.java
Sat, 31 Mar 2018 19:35:04 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Sat, 31 Mar 2018 19:35:04 +0200
- changeset 20
- bd1a76c91d5b
- parent 18
- a94b172c3a93
- child 21
- b213fef2539e
- permissions
- -rw-r--r--
module synchronization with database
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.io.IOException;
32 import java.lang.reflect.Method;
33 import java.lang.reflect.Modifier;
34 import java.util.Arrays;
35 import java.util.HashMap;
36 import java.util.List;
37 import java.util.Locale;
38 import java.util.Map;
39 import java.util.Optional;
40 import javax.servlet.ServletException;
41 import javax.servlet.http.HttpServlet;
42 import javax.servlet.http.HttpServletRequest;
43 import javax.servlet.http.HttpServletResponse;
44 import javax.servlet.http.HttpSession;
45 import org.slf4j.Logger;
46 import org.slf4j.LoggerFactory;
48 /**
49 * A special implementation of a HTTPServlet which is focused on implementing
50 * the necessary functionality for {@link LightPITModule}s.
51 */
52 public abstract class AbstractLightPITServlet extends HttpServlet {
54 private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
56 private static final String HTML_FULL_DISPATCHER = Functions.jspPath("html_full");
58 /**
59 * Store a reference to the annotation for quicker access.
60 */
61 private Optional<LightPITModule> moduleInfo = Optional.empty();
63 /**
64 * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
65 */
66 private Optional<LightPITModule.ELProxy> moduleInfoELProxy = Optional.empty();
69 @FunctionalInterface
70 private static interface HandlerMethod {
71 ResponseType apply(HttpServletRequest t, HttpServletResponse u) throws IOException, ServletException;
72 }
74 /**
75 * Invocation mapping gathered from the {@link RequestMapping} annotations.
76 *
77 * Paths in this map must always start with a leading slash, although
78 * the specification in the annotation must not start with a leading slash.
79 *
80 * The reason for this is the different handling of empty paths in
81 * {@link HttpServletRequest#getPathInfo()}.
82 */
83 private final Map<HttpMethod, Map<String, HandlerMethod>> mappings = new HashMap<>();
85 /**
86 * Gives implementing modules access to the {@link ModuleManager}.
87 * @return the module manager
88 */
89 protected final ModuleManager getModuleManager() {
90 return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
91 }
93 /**
94 * Gives implementing modules access to the {@link DatabaseFacade}.
95 * @return the database facade
96 */
97 protected final DatabaseFacade getDatabaseFacade() {
98 return (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
99 }
101 private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp)
102 throws IOException, ServletException {
103 try {
104 LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
105 return (ResponseType) method.invoke(this, req, resp);
106 } catch (ReflectiveOperationException | ClassCastException ex) {
107 LOG.error(String.format("invocation of method %s failed", method.getName()), ex);
108 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
109 return ResponseType.NONE;
110 }
111 }
113 @Override
114 public void init() throws ServletException {
115 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class));
116 moduleInfoELProxy = moduleInfo.map(LightPITModule.ELProxy::convert);
118 if (moduleInfo.isPresent()) {
119 scanForRequestMappings();
120 }
122 LOG.trace("{} initialized", getServletName());
123 }
125 private void scanForRequestMappings() {
126 try {
127 Method[] methods = getClass().getDeclaredMethods();
128 for (Method method : methods) {
129 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
130 if (mapping.isPresent()) {
131 if (!Modifier.isPublic(method.getModifiers())) {
132 LOG.warn("{} is annotated with {} but is not public",
133 method.getName(), RequestMapping.class.getSimpleName()
134 );
135 continue;
136 }
137 if (Modifier.isAbstract(method.getModifiers())) {
138 LOG.warn("{} is annotated with {} but is abstract",
139 method.getName(), RequestMapping.class.getSimpleName()
140 );
141 continue;
142 }
143 if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
144 LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
145 method.getName(), RequestMapping.class.getSimpleName()
146 );
147 continue;
148 }
150 Class<?>[] params = method.getParameterTypes();
151 if (params.length == 2
152 && HttpServletRequest.class.isAssignableFrom(params[0])
153 && HttpServletResponse.class.isAssignableFrom(params[1])) {
155 final String requestPath = "/"+mapping.get().requestPath();
157 if (mappings.computeIfAbsent(mapping.get().method(), k -> new HashMap<>()).
158 putIfAbsent(requestPath,
159 (req, resp) -> invokeMapping(method, req, resp)) != null) {
160 LOG.warn("{} {} has multiple mappings",
161 mapping.get().method(),
162 mapping.get().requestPath()
163 );
164 }
166 LOG.info("{} {} maps to {}",
167 mapping.get().method(),
168 requestPath,
169 method.getName()
170 );
171 } else {
172 LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse) required",
173 method.getName(), RequestMapping.class.getSimpleName()
174 );
175 }
176 }
177 }
178 } catch (SecurityException ex) {
179 LOG.error("Scan for request mappings on declared methods failed.", ex);
180 }
181 }
183 @Override
184 public void destroy() {
185 mappings.clear();
186 LOG.trace("{} destroyed", getServletName());
187 }
189 /**
190 * Sets the name of the dynamic fragment.
191 *
192 * It is sufficient to specify the name without any extension. The extension
193 * is added automatically if not specified.
194 *
195 * The fragment must be located in the dynamic fragments folder.
196 *
197 * @param req the servlet request object
198 * @param fragmentName the name of the fragment
199 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
200 */
201 public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
202 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
203 }
205 /**
206 * Specifies the name of an additional stylesheet used by the module.
207 *
208 * Setting an additional stylesheet is optional, but quite common for HTML
209 * output.
210 *
211 * It is sufficient to specify the name without any extension. The extension
212 * is added automatically if not specified.
213 *
214 * @param req the servlet request object
215 * @param stylesheet the name of the stylesheet
216 */
217 public void setStylesheet(HttpServletRequest req, String stylesheet) {
218 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
219 }
221 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
222 throws IOException, ServletException {
224 req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
225 req.getRequestDispatcher(HTML_FULL_DISPATCHER).forward(req, resp);
226 }
228 private Optional<HandlerMethod> findMapping(HttpMethod method, HttpServletRequest req) {
229 return Optional.ofNullable(mappings.get(method)).map(
230 (rm) -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse("/"))
231 );
232 }
234 private void forwardAsSepcified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
235 throws ServletException, IOException {
236 switch (type) {
237 case NONE: return;
238 case HTML_FULL:
239 forwardToFullView(req, resp);
240 return;
241 // TODO: implement remaining response types
242 default:
243 // this code should be unreachable
244 LOG.error("ResponseType switch is not exhaustive - this is a bug!");
245 throw new UnsupportedOperationException();
246 }
247 }
249 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp)
250 throws ServletException, IOException {
252 // Synchronize module information with database
253 getModuleManager().syncWithDatabase(getDatabaseFacade());
255 // choose the requested language as session language (if available) or fall back to english, otherwise
256 HttpSession session = req.getSession();
257 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
258 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
259 Optional<Locale> reqLocale = Optional.of(req.getLocale());
260 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
261 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
262 LOG.debug("Settng language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
263 } else {
264 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
265 resp.setLocale(sessionLocale);
266 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
267 }
269 req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
270 req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
271 moduleInfoELProxy.ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
273 Optional<HandlerMethod> mapping = findMapping(method, req);
274 if (mapping.isPresent()) {
275 forwardAsSepcified(mapping.get().apply(req, resp), req, resp);
276 } else {
277 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
278 }
279 }
281 @Override
282 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
283 throws ServletException, IOException {
284 doProcess(HttpMethod.GET, req, resp);
285 }
287 @Override
288 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
289 throws ServletException, IOException {
290 doProcess(HttpMethod.POST, req, resp);
291 }
292 }
