src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@dca186d3911f
src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java
Fri, 22 May 2020 16:21:31 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Fri, 22 May 2020 16:21:31 +0200
- changeset 71
- dca186d3911f
- parent 70
- 821c4950b619
- child 73
- 672b5003cafe
- permissions
- -rw-r--r--
adds breadcrumb menu
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.Constructor;
43 import java.lang.reflect.Method;
44 import java.lang.reflect.Modifier;
45 import java.sql.Connection;
46 import java.sql.SQLException;
47 import java.util.*;
48 import java.util.function.Function;
50 /**
51 * A special implementation of a HTTPServlet which is focused on implementing
52 * the necessary functionality for {@link LightPITModule}s.
53 */
54 public abstract class AbstractLightPITServlet extends HttpServlet {
56 private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
58 private static final String SITE_JSP = Functions.jspPath("site");
60 /**
61 * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
62 */
63 private LightPITModule.ELProxy moduleInfo = null;
65 @FunctionalInterface
66 protected interface SQLFindFunction<K, T> {
67 T apply(K key) throws SQLException;
69 default <V> SQLFindFunction<V, T> compose(Function<? super V, ? extends K> before) throws SQLException {
70 Objects.requireNonNull(before);
71 return (v) -> this.apply(before.apply(v));
72 }
74 default <V> SQLFindFunction<K, V> andThen(Function<? super T, ? extends V> after) throws SQLException {
75 Objects.requireNonNull(after);
76 return (t) -> after.apply(this.apply(t));
77 }
79 static <K> Function<K, K> identity() {
80 return (t) -> t;
81 }
82 }
84 /**
85 * Invocation mapping gathered from the {@link RequestMapping} annotations.
86 * <p>
87 * Paths in this map must always start with a leading slash, although
88 * the specification in the annotation must not start with a leading slash.
89 * <p>
90 * The reason for this is the different handling of empty paths in
91 * {@link HttpServletRequest#getPathInfo()}.
92 */
93 private final Map<HttpMethod, Map<String, Method>> mappings = new HashMap<>();
95 /**
96 * Gives implementing modules access to the {@link ModuleManager}.
97 *
98 * @return the module manager
99 */
100 protected final ModuleManager getModuleManager() {
101 return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
102 }
105 /**
106 * Creates a set of data access objects for the specified connection.
107 *
108 * @param connection the SQL connection
109 * @return a set of data access objects
110 */
111 private DataAccessObjects createDataAccessObjects(Connection connection) throws SQLException {
112 final var df = (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
113 if (df.getSQLDialect() == DatabaseFacade.Dialect.Postgres) {
114 return new PGDataAccessObjects(connection);
115 }
116 throw new AssertionError("Non-exhaustive if-else - this is a bug.");
117 }
119 private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp, DataAccessObjects dao) throws IOException {
120 try {
121 LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
122 final var paramTypes = method.getParameterTypes();
123 final var paramValues = new Object[paramTypes.length];
124 for (int i = 0; i < paramTypes.length; i++) {
125 if (paramTypes[i].isAssignableFrom(HttpServletRequest.class)) {
126 paramValues[i] = req;
127 } else if (paramTypes[i].isAssignableFrom(HttpServletResponse.class)) {
128 paramValues[i] = resp;
129 }
130 if (paramTypes[i].isAssignableFrom(DataAccessObjects.class)) {
131 paramValues[i] = dao;
132 }
133 }
134 return (ResponseType) method.invoke(this, paramValues);
135 } catch (ReflectiveOperationException | ClassCastException ex) {
136 LOG.error("invocation of method {} failed: {}", method.getName(), ex.getMessage());
137 LOG.debug("Details: ", ex);
138 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
139 return ResponseType.NONE;
140 }
141 }
143 @Override
144 public void init() throws ServletException {
145 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class))
146 .map(LightPITModule.ELProxy::new).orElse(null);
148 if (moduleInfo != null) {
149 scanForRequestMappings();
150 }
152 LOG.trace("{} initialized", getServletName());
153 }
155 private void scanForRequestMappings() {
156 try {
157 Method[] methods = getClass().getDeclaredMethods();
158 for (Method method : methods) {
159 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
160 if (mapping.isPresent()) {
161 if (!Modifier.isPublic(method.getModifiers())) {
162 LOG.warn("{} is annotated with {} but is not public",
163 method.getName(), RequestMapping.class.getSimpleName()
164 );
165 continue;
166 }
167 if (Modifier.isAbstract(method.getModifiers())) {
168 LOG.warn("{} is annotated with {} but is abstract",
169 method.getName(), RequestMapping.class.getSimpleName()
170 );
171 continue;
172 }
173 if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
174 LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
175 method.getName(), RequestMapping.class.getSimpleName()
176 );
177 continue;
178 }
180 boolean paramsInjectible = true;
181 for (var param : method.getParameterTypes()) {
182 paramsInjectible &= HttpServletRequest.class.isAssignableFrom(param)
183 || HttpServletResponse.class.isAssignableFrom(param)
184 || DataAccessObjects.class.isAssignableFrom(param);
185 }
186 if (paramsInjectible) {
187 String requestPath = "/" + mapping.get().requestPath();
189 if (mappings
190 .computeIfAbsent(mapping.get().method(), k -> new HashMap<>())
191 .putIfAbsent(requestPath, method) != null) {
192 LOG.warn("{} {} has multiple mappings",
193 mapping.get().method(),
194 mapping.get().requestPath()
195 );
196 }
198 LOG.debug("{} {} maps to {}::{}",
199 mapping.get().method(),
200 requestPath,
201 getClass().getSimpleName(),
202 method.getName()
203 );
204 } else {
205 LOG.warn("{} is annotated with {} but has the wrong parameters - only HttpServletRequest. HttpServletResponse, and DataAccessObjects are allowed",
206 method.getName(), RequestMapping.class.getSimpleName()
207 );
208 }
209 }
210 }
211 } catch (SecurityException ex) {
212 LOG.error("Scan for request mappings on declared methods failed.", ex);
213 }
214 }
216 @Override
217 public void destroy() {
218 mappings.clear();
219 LOG.trace("{} destroyed", getServletName());
220 }
222 /**
223 * Sets the name of the dynamic fragment.
224 * <p>
225 * It is sufficient to specify the name without any extension. The extension
226 * is added automatically if not specified.
227 * <p>
228 * The fragment must be located in the dynamic fragments folder.
229 *
230 * @param req the servlet request object
231 * @param fragmentName the name of the fragment
232 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
233 * @see Constants#REQ_ATTR_FRAGMENT
234 */
235 protected void setDynamicFragment(HttpServletRequest req, String fragmentName) {
236 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
237 }
239 /**
240 * Sets the breadcrumbs menu.
241 *
242 * @param req the servlet request object
243 * @param breadcrumbs the menu entries for the breadcrumbs menu
244 * @see Constants#REQ_ATTR_BREADCRUMBS
245 */
246 protected void setBreadcrumbs(HttpServletRequest req, List<MenuEntry> breadcrumbs) {
247 req.setAttribute(Constants.REQ_ATTR_BREADCRUMBS, breadcrumbs);
248 }
250 /**
251 * @param req the servlet request object
252 * @param location the location where to redirect
253 * @see Constants#REQ_ATTR_REDIRECT_LOCATION
254 */
255 protected void setRedirectLocation(HttpServletRequest req, String location) {
256 if (location.startsWith("./")) {
257 location = location.replaceFirst("\\./", Functions.baseHref(req));
258 }
259 req.setAttribute(Constants.REQ_ATTR_REDIRECT_LOCATION, location);
260 }
262 /**
263 * Specifies the name of an additional stylesheet used by the module.
264 * <p>
265 * Setting an additional stylesheet is optional, but quite common for HTML
266 * output.
267 * <p>
268 * It is sufficient to specify the name without any extension. The extension
269 * is added automatically if not specified.
270 *
271 * @param req the servlet request object
272 * @param stylesheet the name of the stylesheet
273 */
274 public void setStylesheet(HttpServletRequest req, String stylesheet) {
275 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
276 }
278 /**
279 * Obtains a request parameter of the specified type.
280 * The specified type must have a single-argument constructor accepting a string to perform conversion.
281 * The constructor of the specified type may throw an exception on conversion failures.
282 *
283 * @param req the servlet request object
284 * @param clazz the class object of the expected type
285 * @param name the name of the parameter
286 * @param <T> the expected type
287 * @return the parameter value or an empty optional, if no parameter with the specified name was found
288 */
289 protected <T> Optional<T> getParameter(HttpServletRequest req, Class<T> clazz, String name) {
290 final String paramValue = req.getParameter(name);
291 if (paramValue == null) return Optional.empty();
292 if (clazz.equals(String.class)) return Optional.of((T) paramValue);
293 try {
294 final Constructor<T> ctor = clazz.getConstructor(String.class);
295 return Optional.of(ctor.newInstance(paramValue));
296 } catch (ReflectiveOperationException e) {
297 throw new RuntimeException(e);
298 }
300 }
302 /**
303 * Tries to look up an entity with a key obtained from a request parameter.
304 *
305 * @param req the servlet request object
306 * @param clazz the class representing the type of the request parameter
307 * @param name the name of the request parameter
308 * @param find the find function (typically a DAO function)
309 * @param <T> the type of the request parameter
310 * @param <R> the type of the looked up entity
311 * @return the retrieved entity or an empty optional if there is no such entity or the request parameter was missing
312 * @throws SQLException if the find function throws an exception
313 */
314 protected <T, R> Optional<R> findByParameter(HttpServletRequest req, Class<T> clazz, String name, SQLFindFunction<? super T, ? extends R> find) throws SQLException {
315 final var param = getParameter(req, clazz, name);
316 if (param.isPresent()) {
317 return Optional.ofNullable(find.apply(param.get()));
318 } else {
319 return Optional.empty();
320 }
321 }
323 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
324 throws IOException, ServletException {
326 final var mainMenu = new ArrayList<MenuEntry>(getModuleManager().getMainMenu());
327 for (var entry : mainMenu) {
328 if (Functions.fullPath(req).startsWith("/" + entry.getPathName())) {
329 entry.setActive(true);
330 }
331 }
332 req.setAttribute(Constants.REQ_ATTR_MENU, mainMenu);
333 req.getRequestDispatcher(SITE_JSP).forward(req, resp);
334 }
336 private String sanitizeRequestPath(HttpServletRequest req) {
337 return Optional.ofNullable(req.getPathInfo()).orElse("/");
338 }
340 private Optional<Method> findMapping(HttpMethod method, HttpServletRequest req) {
341 return Optional.ofNullable(mappings.get(method)).map(rm -> rm.get(sanitizeRequestPath(req)));
342 }
344 private void forwardAsSpecified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
345 throws ServletException, IOException {
346 switch (type) {
347 case NONE:
348 return;
349 case HTML:
350 forwardToFullView(req, resp);
351 return;
352 // TODO: implement remaining response types
353 default:
354 throw new AssertionError("ResponseType switch is not exhaustive - this is a bug!");
355 }
356 }
358 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
360 // choose the requested language as session language (if available) or fall back to english, otherwise
361 HttpSession session = req.getSession();
362 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
363 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
364 Optional<Locale> reqLocale = Optional.of(req.getLocale());
365 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
366 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
367 LOG.debug("Setting language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
368 } else {
369 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
370 resp.setLocale(sessionLocale);
371 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
372 }
374 // set some internal request attributes
375 final String fullPath = Functions.fullPath(req);
376 req.setAttribute(Constants.REQ_ATTR_BASE_HREF, Functions.baseHref(req));
377 req.setAttribute(Constants.REQ_ATTR_PATH, fullPath);
378 Optional.ofNullable(moduleInfo).ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
380 // if this is an error path, bypass the normal flow
381 if (fullPath.startsWith("/error/")) {
382 final var mapping = findMapping(method, req);
383 if (mapping.isPresent()) {
384 forwardAsSpecified(invokeMapping(mapping.get(), req, resp, null), req, resp);
385 }
386 return;
387 }
389 // obtain a connection and create the data access objects
390 final var db = (DatabaseFacade) req.getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
391 final var ds = db.getDataSource();
392 if (ds == null) {
393 resp.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, "JNDI DataSource lookup failed. See log for details.");
394 return;
395 }
396 try (final var connection = ds.getConnection()) {
397 final var dao = createDataAccessObjects(connection);
398 try {
399 connection.setAutoCommit(false);
400 // call the handler, if available, or send an HTTP 404 error
401 final var mapping = findMapping(method, req);
402 if (mapping.isPresent()) {
403 forwardAsSpecified(invokeMapping(mapping.get(), req, resp, dao), req, resp);
404 } else {
405 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
406 }
407 connection.commit();
408 } catch (SQLException ex) {
409 LOG.warn("Database transaction failed (Code {}): {}", ex.getErrorCode(), ex.getMessage());
410 LOG.debug("Details: ", ex);
411 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Unhandled Transaction Error - Code: " + ex.getErrorCode());
412 connection.rollback();
413 }
414 } catch (SQLException ex) {
415 LOG.error("Severe Database Exception (Code {}): {}", ex.getErrorCode(), ex.getMessage());
416 LOG.debug("Details: ", ex);
417 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Database Error - Code: " + ex.getErrorCode());
418 }
419 }
421 @Override
422 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
423 throws ServletException, IOException {
424 doProcess(HttpMethod.GET, req, resp);
425 }
427 @Override
428 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
429 throws ServletException, IOException {
430 doProcess(HttpMethod.POST, req, resp);
431 }
432 }
