src/java/de/uapcore/lightpit/AbstractLightPITServlet.java@bb594abac796
src/java/de/uapcore/lightpit/AbstractLightPITServlet.java
Tue, 26 Dec 2017 19:45:31 +0100
- author
- Mike Becker <universe@uap-core.de>
- date
- Tue, 26 Dec 2017 19:45:31 +0100
- changeset 15
- bb594abac796
- parent 14
- 2b270c714678
- child 17
- d1036b776eee
- permissions
- -rw-r--r--
language selector completed
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 private final Map<HttpMethod, Map<String, HandlerMethod>> mappings = new HashMap<>();
79 /**
80 * Gives implementing modules access to the {@link ModuleManager}.
81 * @return the module manager
82 */
83 protected final ModuleManager getModuleManager() {
84 return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
85 }
87 private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp)
88 throws IOException, ServletException {
89 try {
90 LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
91 return (ResponseType) method.invoke(this, req, resp);
92 } catch (ReflectiveOperationException | ClassCastException ex) {
93 LOG.error(String.format("invocation of method %s failed", method.getName()), ex);
94 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
95 return ResponseType.NONE;
96 }
97 }
99 @Override
100 public void init() throws ServletException {
101 moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class));
102 moduleInfoELProxy = moduleInfo.map(LightPITModule.ELProxy::convert);
104 if (moduleInfo.isPresent()) {
105 scanForRequestMappings();
106 }
108 LOG.trace("{} initialized", getServletName());
109 }
111 private void scanForRequestMappings() {
112 try {
113 Method[] methods = getClass().getDeclaredMethods();
114 for (Method method : methods) {
115 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
116 if (mapping.isPresent()) {
117 if (!Modifier.isPublic(method.getModifiers())) {
118 LOG.warn("{} is annotated with {} but is not public",
119 method.getName(), RequestMapping.class.getSimpleName()
120 );
121 continue;
122 }
123 if (Modifier.isAbstract(method.getModifiers())) {
124 LOG.warn("{} is annotated with {} but is abstract",
125 method.getName(), RequestMapping.class.getSimpleName()
126 );
127 continue;
128 }
129 if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
130 LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
131 method.getName(), RequestMapping.class.getSimpleName()
132 );
133 continue;
134 }
136 Class<?>[] params = method.getParameterTypes();
137 if (params.length == 2
138 && HttpServletRequest.class.isAssignableFrom(params[0])
139 && HttpServletResponse.class.isAssignableFrom(params[1])) {
141 if (mappings.computeIfAbsent(mapping.get().method(), k -> new HashMap<>()).
142 putIfAbsent(mapping.get().requestPath(),
143 (req, resp) -> invokeMapping(method, req, resp)) != null) {
144 LOG.warn("{} {} has multiple mappings",
145 mapping.get().method(),
146 mapping.get().requestPath()
147 );
148 }
150 LOG.info("{} {} maps to {}",
151 mapping.get().method(),
152 mapping.get().requestPath(),
153 method.getName()
154 );
155 } else {
156 LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse) required",
157 method.getName(), RequestMapping.class.getSimpleName()
158 );
159 }
160 }
161 }
162 } catch (SecurityException ex) {
163 LOG.error("Scan for request mappings on declared methods failed.", ex);
164 }
165 }
167 @Override
168 public void destroy() {
169 mappings.clear();
170 LOG.trace("{} destroyed", getServletName());
171 }
173 /**
174 * Sets the name of the dynamic fragment.
175 *
176 * It is sufficient to specify the name without any extension. The extension
177 * is added automatically if not specified.
178 *
179 * The fragment must be located in the dynamic fragments folder.
180 *
181 * @param req the servlet request object
182 * @param fragmentName the name of the fragment
183 * @see Constants#DYN_FRAGMENT_PATH_PREFIX
184 */
185 public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
186 req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
187 }
189 /**
190 * Specifies the name of an additional stylesheet used by the module.
191 *
192 * Setting an additional stylesheet is optional, but quite common for HTML
193 * output.
194 *
195 * It is sufficient to specify the name without any extension. The extension
196 * is added automatically if not specified.
197 *
198 * @param req the servlet request object
199 * @param stylesheet the name of the stylesheet
200 */
201 public void setStylesheet(HttpServletRequest req, String stylesheet) {
202 req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
203 }
205 private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
206 throws IOException, ServletException {
208 req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
209 req.getRequestDispatcher(HTML_FULL_DISPATCHER).forward(req, resp);
210 }
212 private Optional<HandlerMethod> findMapping(HttpMethod method, HttpServletRequest req) {
213 return Optional.ofNullable(mappings.get(method)).map(
214 (rm) -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse(""))
215 );
216 }
218 private void forwardAsSepcified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
219 throws ServletException, IOException {
220 switch (type) {
221 case NONE: return;
222 case HTML_FULL:
223 forwardToFullView(req, resp);
224 return;
225 // TODO: implement remaining response types
226 default:
227 // this code should be unreachable
228 LOG.error("ResponseType switch is not exhaustive - this is a bug!");
229 throw new UnsupportedOperationException();
230 }
231 }
233 private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp)
234 throws ServletException, IOException {
236 HttpSession session = req.getSession();
238 // choose the requested language as session language (if available) or fall back to english, otherwise
239 if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
240 Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
241 Optional<Locale> reqLocale = Optional.of(req.getLocale());
242 Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
243 session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
244 LOG.debug("Settng language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
245 } else {
246 Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
247 resp.setLocale(sessionLocale);
248 LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
249 }
251 req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
252 req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
253 moduleInfoELProxy.ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
255 Optional<HandlerMethod> mapping = findMapping(method, req);
256 if (mapping.isPresent()) {
257 forwardAsSepcified(mapping.get().apply(req, resp), req, resp);
258 } else {
259 resp.sendError(HttpServletResponse.SC_NOT_FOUND);
260 }
261 }
263 @Override
264 protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
265 throws ServletException, IOException {
266 doProcess(HttpMethod.GET, req, resp);
267 }
269 @Override
270 protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
271 throws ServletException, IOException {
272 doProcess(HttpMethod.POST, req, resp);
273 }
274 }
