src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@0f4f8f255c32
src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java
Sun, 10 May 2020 10:11:37 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Sun, 10 May 2020 10:11:37 +0200
- changeset 36
- 0f4f8f255c32
- parent 34
- 824d4042c857
- child 38
- cf85ef18f231
- permissions
- -rw-r--r--
removes features that are not (and probably will not) used anyway
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2018 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 org.slf4j.Logger;
32 import org.slf4j.LoggerFactory;
34 import javax.servlet.ServletException;
35 import javax.servlet.http.HttpServlet;
36 import javax.servlet.http.HttpServletRequest;
37 import javax.servlet.http.HttpServletResponse;
38 import javax.servlet.http.HttpSession;
39 import java.io.IOException;
40 import java.lang.reflect.Method;
41 import java.lang.reflect.Modifier;
42 import java.util.*;
44 /**
45 * A special implementation of a HTTPServlet which is focused on implementing
46 * the necessary functionality for {@link LightPITModule}s.
47 */
48 public abstract class AbstractLightPITServlet extends HttpServlet {
50 private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
52 private static final String HTML_FULL_DISPATCHER = Functions.jspPath("html_full");
54 /**
55 * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
56 */
57 private LightPITModule.ELProxy moduleInfo = null;
60 @FunctionalInterface
61 private interface HandlerMethod {
62 ResponseType apply(HttpServletRequest t, HttpServletResponse u) throws IOException;
63 }
65 /**
66 * Invocation mapping gathered from the {@link RequestMapping} annotations.
67 * <p>
68 * Paths in this map must always start with a leading slash, although
69 * the specification in the annotation must not start with a leading slash.
70 * <p>
71 * The reason for this is the different handling of empty paths in
72 * {@link HttpServletRequest#getPathInfo()}.
73 */
74 private final Map<HttpMethod, Map<String, HandlerMethod>> mappings = new HashMap<>();
76 /**
77 * Gives implementing modules access to the {@link ModuleManager}.
78 *
79 * @return the module manager
80 */
81 protected final ModuleManager getModuleManager() {
82 return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
83 }
85 /**
86 * Gives implementing modules access to the {@link DatabaseFacade}.
87 *
88 * @return the database facade
89 */
90 protected final DatabaseFacade getDatabaseFacade() {
91 return (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
92 }
94 private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp) throws IOException {
95 try {
96 LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
97 return (ResponseType) method.invoke(this, req, resp);
98 } catch (ReflectiveOperationException | ClassCastException ex) {
99 LOG.error(String.format("invocation of method %s failed", method.getName()), ex);
100 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
101 return ResponseType.NONE;
102 }
103 }
105 @Override
106 public void init() throws ServletException {
107 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class))
108 .map(LightPITModule.ELProxy::new).orElse(null);
110 if (moduleInfo != null) {
111 scanForRequestMappings();
112 }
114 LOG.trace("{} initialized", getServletName());
115 }
117 private void scanForRequestMappings() {
118 try {
119 Method[] methods = getClass().getDeclaredMethods();
120 for (Method method : methods) {
121 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
122 if (mapping.isPresent()) {
123 if (!Modifier.isPublic(method.getModifiers())) {
124 LOG.warn("{} is annotated with {} but is not public",
125 method.getName(), RequestMapping.class.getSimpleName()
126 );
127 continue;
128 }
129 if (Modifier.isAbstract(method.getModifiers())) {
130 LOG.warn("{} is annotated with {} but is abstract",
131 method.getName(), RequestMapping.class.getSimpleName()
132 );
133 continue;
134 }
135 if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
136 LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
137 method.getName(), RequestMapping.class.getSimpleName()
138 );
139 continue;
140 }
142 Class<?>[] params = method.getParameterTypes();
143 if (params.length == 2
144 && HttpServletRequest.class.isAssignableFrom(params[0])
145 && HttpServletResponse.class.isAssignableFrom(params[1])) {
147 final String requestPath = "/" + mapping.get().requestPath();
149 if (mappings.computeIfAbsent(mapping.get().method(), k -> new HashMap<>()).
150 putIfAbsent(requestPath,
151 (req, resp) -> invokeMapping(method, req, resp)) != null) {
152 LOG.warn("{} {} has multiple mappings",
153 mapping.get().method(),
154 mapping.get().requestPath()
155 );
156 }
158 LOG.debug("{} {} maps to {}::{}",
159 mapping.get().method(),
160 requestPath,
161 getClass().getSimpleName(),
162 method.getName()
163 );
164 } else {
165 LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse) required",
166 method.getName(), RequestMapping.class.getSimpleName()
167 );
168 }
169 }
170 }
171 } catch (SecurityException ex) {
172 LOG.error("Scan for request mappings on declared methods failed.", ex);
173 }
174 }
176 @Override
177 public void destroy() {
178 mappings.clear();
179 LOG.trace("{} destroyed", getServletName());
180 }
182 /**
183 * Sets the name of the dynamic fragment.
184 * <p>
185 * It is sufficient to specify the name without any extension. The extension
186 * is added automatically if not specified.
187 * <p>
188 * The fragment must be located in the dynamic fragments folder.
189 *
190 * @param req the servlet request object
191 * @param fragmentName the name of the fragment
192 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
193 */
194 public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
195 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
196 }
198 /**
199 * Specifies the name of an additional stylesheet used by the module.
200 * <p>
201 * Setting an additional stylesheet is optional, but quite common for HTML
202 * output.
203 * <p>
204 * It is sufficient to specify the name without any extension. The extension
205 * is added automatically if not specified.
206 *
207 * @param req the servlet request object
208 * @param stylesheet the name of the stylesheet
209 */
210 public void setStylesheet(HttpServletRequest req, String stylesheet) {
211 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
212 }
214 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
215 throws IOException, ServletException {
217 req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
218 req.getRequestDispatcher(HTML_FULL_DISPATCHER).forward(req, resp);
219 }
221 private Optional<HandlerMethod> findMapping(HttpMethod method, HttpServletRequest req) {
222 return Optional.ofNullable(mappings.get(method)).map(
223 (rm) -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse("/"))
224 );
225 }
227 private void forwardAsSpecified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
228 throws ServletException, IOException {
229 switch (type) {
230 case NONE:
231 return;
232 case HTML_FULL:
233 forwardToFullView(req, resp);
234 return;
235 // TODO: implement remaining response types
236 default:
237 throw new AssertionError("ResponseType switch is not exhaustive - this is a bug!");
238 }
239 }
241 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp)
242 throws ServletException, IOException {
244 // choose the requested language as session language (if available) or fall back to english, otherwise
245 HttpSession session = req.getSession();
246 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
247 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
248 Optional<Locale> reqLocale = Optional.of(req.getLocale());
249 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
250 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
251 LOG.debug("Setting language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
252 } else {
253 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
254 resp.setLocale(sessionLocale);
255 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
256 }
258 // set some internal request attributes
259 req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
260 req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
261 Optional.ofNullable(moduleInfo).ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
264 // call the handler, if available, or send an HTTP 404 error
265 Optional<HandlerMethod> mapping = findMapping(method, req);
266 if (mapping.isPresent()) {
267 forwardAsSpecified(mapping.get().apply(req, resp), req, resp);
268 } else {
269 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
270 }
271 }
273 @Override
274 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
275 throws ServletException, IOException {
276 doProcess(HttpMethod.GET, req, resp);
277 }
279 @Override
280 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
281 throws ServletException, IOException {
282 doProcess(HttpMethod.POST, req, resp);
283 }
284 }
