src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@9abf0bf44c7b
src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java
Wed, 13 May 2020 18:45:28 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Wed, 13 May 2020 18:45:28 +0200
- changeset 43
- 9abf0bf44c7b
- parent 42
- f962ff9dd44e
- child 45
- cc7f082c5ef3
- permissions
- -rw-r--r--
renames some crappy constants
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 de.uapcore.lightpit.dao.DataAccessObjects;
32 import de.uapcore.lightpit.dao.postgres.PGDataAccessObjects;
33 import org.slf4j.Logger;
34 import org.slf4j.LoggerFactory;
36 import javax.servlet.ServletException;
37 import javax.servlet.http.HttpServlet;
38 import javax.servlet.http.HttpServletRequest;
39 import javax.servlet.http.HttpServletResponse;
40 import javax.servlet.http.HttpSession;
41 import java.io.IOException;
42 import java.lang.reflect.Method;
43 import java.lang.reflect.Modifier;
44 import java.sql.Connection;
45 import java.sql.SQLException;
46 import java.util.*;
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 SITE_JSP = Functions.jspPath("site");
58 /**
59 * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
60 */
61 private LightPITModule.ELProxy moduleInfo = null;
63 /**
64 * Invocation mapping gathered from the {@link RequestMapping} annotations.
65 * <p>
66 * Paths in this map must always start with a leading slash, although
67 * the specification in the annotation must not start with a leading slash.
68 * <p>
69 * The reason for this is the different handling of empty paths in
70 * {@link HttpServletRequest#getPathInfo()}.
71 */
72 private final Map<HttpMethod, Map<String, Method>> mappings = new HashMap<>();
74 /**
75 * Gives implementing modules access to the {@link ModuleManager}.
76 *
77 * @return the module manager
78 */
79 protected final ModuleManager getModuleManager() {
80 return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
81 }
84 /**
85 * Creates a set of data access objects for the specified connection.
86 *
87 * @param connection the SQL connection
88 * @return a set of data access objects
89 */
90 private DataAccessObjects createDataAccessObjects(Connection connection) throws SQLException {
91 final var df = (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
92 if (df.getSQLDialect() == DatabaseFacade.Dialect.Postgres) {
93 return new PGDataAccessObjects(connection);
94 }
95 throw new AssertionError("Non-exhaustive if-else - this is a bug.");
96 }
98 private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp, DataAccessObjects dao) throws IOException {
99 try {
100 LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
101 final var paramTypes = method.getParameterTypes();
102 final var paramValues = new Object[paramTypes.length];
103 for (int i = 0; i < paramTypes.length; i++) {
104 if (paramTypes[i].isAssignableFrom(HttpServletRequest.class)) {
105 paramValues[i] = req;
106 } else if (paramTypes[i].isAssignableFrom(HttpServletResponse.class)) {
107 paramValues[i] = resp;
108 }
109 if (paramTypes[i].isAssignableFrom(DataAccessObjects.class)) {
110 paramValues[i] = dao;
111 }
112 }
113 return (ResponseType) method.invoke(this, paramValues);
114 } catch (ReflectiveOperationException | ClassCastException ex) {
115 LOG.error("invocation of method {} failed: {}", method.getName(), ex.getMessage());
116 LOG.debug("Details: ", ex);
117 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
118 return ResponseType.NONE;
119 }
120 }
122 @Override
123 public void init() throws ServletException {
124 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class))
125 .map(LightPITModule.ELProxy::new).orElse(null);
127 if (moduleInfo != null) {
128 scanForRequestMappings();
129 }
131 LOG.trace("{} initialized", getServletName());
132 }
134 private void scanForRequestMappings() {
135 try {
136 Method[] methods = getClass().getDeclaredMethods();
137 for (Method method : methods) {
138 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
139 if (mapping.isPresent()) {
140 if (!Modifier.isPublic(method.getModifiers())) {
141 LOG.warn("{} is annotated with {} but is not public",
142 method.getName(), RequestMapping.class.getSimpleName()
143 );
144 continue;
145 }
146 if (Modifier.isAbstract(method.getModifiers())) {
147 LOG.warn("{} is annotated with {} but is abstract",
148 method.getName(), RequestMapping.class.getSimpleName()
149 );
150 continue;
151 }
152 if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
153 LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
154 method.getName(), RequestMapping.class.getSimpleName()
155 );
156 continue;
157 }
159 boolean paramsInjectible = true;
160 for (var param : method.getParameterTypes()) {
161 paramsInjectible &= HttpServletRequest.class.isAssignableFrom(param)
162 || HttpServletResponse.class.isAssignableFrom(param)
163 || DataAccessObjects.class.isAssignableFrom(param);
164 }
165 if (paramsInjectible) {
166 final String requestPath = "/" + mapping.get().requestPath();
168 if (mappings
169 .computeIfAbsent(mapping.get().method(), k -> new HashMap<>())
170 .putIfAbsent(requestPath, method) != null) {
171 LOG.warn("{} {} has multiple mappings",
172 mapping.get().method(),
173 mapping.get().requestPath()
174 );
175 }
177 LOG.debug("{} {} maps to {}::{}",
178 mapping.get().method(),
179 requestPath,
180 getClass().getSimpleName(),
181 method.getName()
182 );
183 } else {
184 LOG.warn("{} is annotated with {} but has the wrong parameters - only HttpServletRequest. HttpServletResponse, and DataAccessObjects are allowed",
185 method.getName(), RequestMapping.class.getSimpleName()
186 );
187 }
188 }
189 }
190 } catch (SecurityException ex) {
191 LOG.error("Scan for request mappings on declared methods failed.", ex);
192 }
193 }
195 @Override
196 public void destroy() {
197 mappings.clear();
198 LOG.trace("{} destroyed", getServletName());
199 }
201 /**
202 * Sets the name of the dynamic fragment.
203 * <p>
204 * It is sufficient to specify the name without any extension. The extension
205 * is added automatically if not specified.
206 * <p>
207 * The fragment must be located in the dynamic fragments folder.
208 *
209 * @param req the servlet request object
210 * @param fragmentName the name of the fragment
211 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
212 */
213 public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
214 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
215 }
217 /**
218 * Specifies the name of an additional stylesheet used by the module.
219 * <p>
220 * Setting an additional stylesheet is optional, but quite common for HTML
221 * output.
222 * <p>
223 * It is sufficient to specify the name without any extension. The extension
224 * is added automatically if not specified.
225 *
226 * @param req the servlet request object
227 * @param stylesheet the name of the stylesheet
228 */
229 public void setStylesheet(HttpServletRequest req, String stylesheet) {
230 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
231 }
233 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
234 throws IOException, ServletException {
236 req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
237 req.getRequestDispatcher(SITE_JSP).forward(req, resp);
238 }
240 private Optional<Method> findMapping(HttpMethod method, HttpServletRequest req) {
241 return Optional.ofNullable(mappings.get(method))
242 .map(rm -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse("/"))
243 );
244 }
246 private void forwardAsSpecified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
247 throws ServletException, IOException {
248 switch (type) {
249 case NONE:
250 return;
251 case HTML:
252 forwardToFullView(req, resp);
253 return;
254 // TODO: implement remaining response types
255 default:
256 throw new AssertionError("ResponseType switch is not exhaustive - this is a bug!");
257 }
258 }
260 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
262 // choose the requested language as session language (if available) or fall back to english, otherwise
263 HttpSession session = req.getSession();
264 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
265 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
266 Optional<Locale> reqLocale = Optional.of(req.getLocale());
267 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
268 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
269 LOG.debug("Setting language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
270 } else {
271 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
272 resp.setLocale(sessionLocale);
273 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
274 }
276 // set some internal request attributes
277 req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
278 req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
279 Optional.ofNullable(moduleInfo).ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
281 // obtain a connection and create the data access objects
282 final var db = (DatabaseFacade) req.getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
283 try (final var connection = db.getDataSource().getConnection()) {
284 final var dao = createDataAccessObjects(connection);
285 try {
286 connection.setAutoCommit(false);
287 // call the handler, if available, or send an HTTP 404 error
288 final var mapping = findMapping(method, req);
289 if (mapping.isPresent()) {
290 forwardAsSpecified(invokeMapping(mapping.get(), req, resp, dao), req, resp);
291 } else {
292 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
293 }
294 connection.commit();
295 } catch (SQLException ex) {
296 LOG.warn("Database transaction failed (Code {}): {}", ex.getErrorCode(), ex.getMessage());
297 LOG.debug("Details: ", ex);
298 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Unhandled Transaction Error - Code:" + ex.getErrorCode());
299 connection.rollback();
300 }
301 } catch (SQLException ex) {
302 LOG.error("Severe Database Exception (Code {}): {}", ex.getErrorCode(), ex.getMessage());
303 LOG.debug("Details: ", ex);
304 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Database Error - Code:" + ex.getErrorCode());
305 }
306 }
308 @Override
309 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
310 throws ServletException, IOException {
311 doProcess(HttpMethod.GET, req, resp);
312 }
314 @Override
315 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
316 throws ServletException, IOException {
317 doProcess(HttpMethod.POST, req, resp);
318 }
319 }
