LightPIT: src/java/de/uapcore/lightpit/AbstractLightPITServlet.java@005d27918b57 (annotated)

src/java/de/uapcore/lightpit/AbstractLightPITServlet.java@005d27918b57 (annotated)

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

Sat, 23 Dec 2017 17:28:19 +0100

author: Mike Becker <universe@uap-core.de>
date: Sat, 23 Dec 2017 17:28:19 +0100
changeset 12: 005d27918b57
parent 11: 737ab27e37b3
child 13: f4608ad6c947
permissions: -rw-r--r--

implements ResponseTypes

 /*
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Copyright 2017 Mike Becker. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *   1. Redistributions of source code must retain the above copyright
  *      notice, this list of conditions and the following disclaimer.
  *
  *   2. Redistributions in binary form must reproduce the above copyright
  *      notice, this list of conditions and the following disclaimer in the
  *      documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  *
  */
 package de.uapcore.lightpit;
 import java.io.IOException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 /**
  * A special implementation of a HTTPServlet which is focused on implementing
  * the necessary functionality for {@link LightPITModule}s.
  */
 public abstract class AbstractLightPITServlet extends HttpServlet {
     private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
     /**
      * Store a reference to the annotation for quicker access.
      */
     private Optional<LightPITModule> moduleInfo = Optional.empty();
     /**
      * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
      */
     private Optional<LightPITModule.ELProxy> moduleInfoELProxy = Optional.empty();
     @FunctionalInterface
     private static interface HandlerMethod {
         ResponseType apply(HttpServletRequest t, HttpServletResponse u) throws IOException, ServletException;
     }
     /**
      * Invocation mapping gathered from the {@link RequestMapping} annotations.
      */
     private final Map<HttpMethod, Map<String, HandlerMethod>> mappings = new HashMap<>();
     /**
      * Gives implementing modules access to the {@link ModuleManager}.
      * @return the module manager
      */
     protected final ModuleManager getModuleManager() {
         return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
     }
     private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp)
             throws IOException, ServletException {
         try {
             LOG.debug("invoke {}", method.getName());
             return (ResponseType) method.invoke(this, req, resp);
         } catch (ReflectiveOperationException | ClassCastException ex) {
             LOG.error(String.format("invocation of method %s failed", method.getName()), ex);
             resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
             return ResponseType.NONE;
         }
     }
     @Override
     public void init() throws ServletException {
         moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class));
         moduleInfoELProxy = moduleInfo.map(LightPITModule.ELProxy::convert);
         if (moduleInfo.isPresent()) {
             scanForRequestMappings();
         }
         LOG.trace("{} initialized", getServletName());
     }
     private void scanForRequestMappings() {
         try {
             Method[] methods = getClass().getDeclaredMethods();
             for (Method method : methods) {
                 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
                 if (mapping.isPresent()) {
                     if (!Modifier.isPublic(method.getModifiers())) {
                         LOG.warn("{} is annotated with {} but is not public",
                                 method.getName(), RequestMapping.class.getSimpleName()
                         );
                         continue;
                     }
                     if (Modifier.isAbstract(method.getModifiers())) {
                         LOG.warn("{} is annotated with {} but is abstract",
                                 method.getName(), RequestMapping.class.getSimpleName()
                         );
                         continue;
                     }
                     if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
                         LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
                                 method.getName(), RequestMapping.class.getSimpleName()
                         );
                         continue;
                     }
                     Class<?>[] params = method.getParameterTypes();
                     if (params.length == 2
                             && HttpServletRequest.class.isAssignableFrom(params[0])
                             && HttpServletResponse.class.isAssignableFrom(params[1])) {
                         if (mappings.computeIfAbsent(mapping.get().method(), k -> new HashMap<>()).
                                 putIfAbsent(mapping.get().requestPath(),
                                         (req, resp) -> invokeMapping(method, req, resp)) != null) {
                             LOG.warn("{} {} has multiple mappings",
                                     mapping.get().method(),
                                     mapping.get().requestPath()
                             );
                         }
                         LOG.info("{} {} maps to {}",
                                 mapping.get().method(),
                                 mapping.get().requestPath(),
                                 method.getName()
                         );
                     } else {
                         LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse) required",
                                 method.getName(), RequestMapping.class.getSimpleName()
                         );
                     }
                 }
             }
         } catch (SecurityException ex) {
             LOG.error("Scan for request mappings on declared methods failed.", ex);
         }
     }
     @Override
     public void destroy() {
         mappings.clear();
         LOG.trace("{} destroyed", getServletName());
     }
     /**
      * Sets several requests attributes, that can be used by the JSP.
      *
      * @param req the servlet request object
      * @see Constants#REQ_ATTR_PATH
      * @see Constants#REQ_ATTR_MODULE_CLASSNAME
      * @see Constants#REQ_ATTR_MODULE_INFO
      */
     private void setGenericRequestAttributes(HttpServletRequest req) {
         req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
         req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
         moduleInfoELProxy.ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
     }
     private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
             throws IOException, ServletException {
         setGenericRequestAttributes(req);
         req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
         req.getRequestDispatcher(Functions.jspPath("full.jsp")).forward(req, resp);
     }
     private Optional<HandlerMethod> findMapping(HttpMethod method, HttpServletRequest req) {
         return Optional.ofNullable(mappings.get(method)).map(
                 (rm) -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse(""))
         );
     }
     private void forwardAsSepcified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         switch (type) {
             case NONE: return;
             case HTML_FULL:
                 forwardToFullView(req, resp);
                 return;
             // TODO: implement remaining response types
             default:
                 // this code should be unreachable
                 LOG.error("ResponseType switch is not exhaustive - this is a bug!");
                 throw new UnsupportedOperationException();
         }
     }
     private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         Optional<HandlerMethod> mapping = findMapping(method, req);
         if (mapping.isPresent()) {
             forwardAsSepcified(mapping.get().apply(req, resp), req, resp);
         } else {
             resp.sendError(HttpServletResponse.SC_NOT_FOUND);
         }
     }
     @Override
     protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         doProcess(HttpMethod.GET, req, resp);
     }
     @Override
     protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         doProcess(HttpMethod.POST, req, resp);
     }
 }

Mercurial > hg > LightPIT / annotate

src/java/de/uapcore/lightpit/AbstractLightPITServlet.java@005d27918b57 (annotated)

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