Mercurial > hg > LightPIT / file comparison

comparison: src/java/de/uapcore/lightpit/AbstractLightPITServlet.java

src/java/de/uapcore/lightpit/AbstractLightPITServlet.java

changeset 29
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parent 28
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child 30
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equal deleted inserted replaced
28:cfc3d11884ad 29:27a0fdd7bca7
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;
30
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;
47
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 {
53
54 private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
55
56 private static final String HTML_FULL_DISPATCHER = Functions.jspPath("html_full");
57
58 /**
59 * Store a reference to the annotation for quicker access.
60 */
61 private Optional<LightPITModule> moduleInfo = Optional.empty();
62
63 /**
64 * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
65 */
66 private Optional<LightPITModule.ELProxy> moduleInfoELProxy = Optional.empty();
67
68
69 @FunctionalInterface
70 private static interface HandlerMethod {
71 ResponseType apply(HttpServletRequest t, HttpServletResponse u) throws IOException, ServletException;
72 }
73
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<>();
84
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 }
92
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 }
100
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 }
112
113 @Override
114 public void init() throws ServletException {
115 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class));
116 moduleInfoELProxy = moduleInfo.map(LightPITModule.ELProxy::convert);
117
118 if (moduleInfo.isPresent()) {
119 scanForRequestMappings();
120 }
121
122 LOG.trace("{} initialized", getServletName());
123 }
124
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 }
149
150 Class<?>[] params = method.getParameterTypes();
151 if (params.length == 2
152 && HttpServletRequest.class.isAssignableFrom(params[0])
153 && HttpServletResponse.class.isAssignableFrom(params[1])) {
154
155 final String requestPath = "/"+mapping.get().requestPath();
156
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 }
165
166 LOG.debug("{} {} maps to {}::{}",
167 mapping.get().method(),
168 requestPath,
169 getClass().getSimpleName(),
170 method.getName()
171 );
172 } else {
173 LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse) required",
174 method.getName(), RequestMapping.class.getSimpleName()
175 );
176 }
177 }
178 }
179 } catch (SecurityException ex) {
180 LOG.error("Scan for request mappings on declared methods failed.", ex);
181 }
182 }
183
184 @Override
185 public void destroy() {
186 mappings.clear();
187 LOG.trace("{} destroyed", getServletName());
188 }
189
190 /**
191 * Sets the name of the dynamic fragment.
192 *
193 * It is sufficient to specify the name without any extension. The extension
194 * is added automatically if not specified.
195 *
196 * The fragment must be located in the dynamic fragments folder.
197 *
198 * @param req the servlet request object
199 * @param fragmentName the name of the fragment
200 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
201 */
202 public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
203 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
204 }
205
206 /**
207 * Specifies the name of an additional stylesheet used by the module.
208 *
209 * Setting an additional stylesheet is optional, but quite common for HTML
210 * output.
211 *
212 * It is sufficient to specify the name without any extension. The extension
213 * is added automatically if not specified.
214 *
215 * @param req the servlet request object
216 * @param stylesheet the name of the stylesheet
217 */
218 public void setStylesheet(HttpServletRequest req, String stylesheet) {
219 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
220 }
221
222 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
223 throws IOException, ServletException {
224
225 req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu(getDatabaseFacade()));
226 req.getRequestDispatcher(HTML_FULL_DISPATCHER).forward(req, resp);
227 }
228
229 private Optional<HandlerMethod> findMapping(HttpMethod method, HttpServletRequest req) {
230 return Optional.ofNullable(mappings.get(method)).map(
231 (rm) -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse("/"))
232 );
233 }
234
235 private void forwardAsSepcified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
236 throws ServletException, IOException {
237 switch (type) {
238 case NONE: return;
239 case HTML_FULL:
240 forwardToFullView(req, resp);
241 return;
242 // TODO: implement remaining response types
243 default:
244 // this code should be unreachable
245 LOG.error("ResponseType switch is not exhaustive - this is a bug!");
246 throw new UnsupportedOperationException();
247 }
248 }
249
250 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp)
251 throws ServletException, IOException {
252
253 // Synchronize module information with database
254 getModuleManager().syncWithDatabase(getDatabaseFacade());
255
256 // choose the requested language as session language (if available) or fall back to english, otherwise
257 HttpSession session = req.getSession();
258 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
259 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
260 Optional<Locale> reqLocale = Optional.of(req.getLocale());
261 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
262 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
263 LOG.debug("Settng language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
264 } else {
265 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
266 resp.setLocale(sessionLocale);
267 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
268 }
269
270 // set some internal request attributes
271 req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
272 req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
273 moduleInfoELProxy.ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
274
275
276 // call the handler, if available, or send an HTTP 404 error
277 Optional<HandlerMethod> mapping = findMapping(method, req);
278 if (mapping.isPresent()) {
279 forwardAsSepcified(mapping.get().apply(req, resp), req, resp);
280 } else {
281 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
282 }
283 }
284
285 @Override
286 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
287 throws ServletException, IOException {
288 doProcess(HttpMethod.GET, req, resp);
289 }
290
291 @Override
292 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
293 throws ServletException, IOException {
294 doProcess(HttpMethod.POST, req, resp);
295 }
296 }

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