LightPIT: src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@51aa5e267c7f (annotated)

src/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@51aa5e267c7f (annotated)

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

Mon, 18 May 2020 21:06:38 +0200

author: Mike Becker <universe@uap-core.de>
date: Mon, 18 May 2020 21:06:38 +0200
changeset 63: 51aa5e267c7f
parent 58: 8d3047f78190
child 70: 821c4950b619
permissions: -rw-r--r--

adds utility function to find an entity by ID (reduces code duplication)

 /*
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Copyright 2018 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 de.uapcore.lightpit.dao.DataAccessObjects;
 import de.uapcore.lightpit.dao.postgres.PGDataAccessObjects;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.*;
 import java.util.function.Function;
 /**
  * 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);
     private static final String SITE_JSP = Functions.jspPath("site");
     /**
      * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
      */
     private LightPITModule.ELProxy moduleInfo = null;
     @FunctionalInterface
     protected interface SQLFindFunction<K, T> {
         T apply(K key) throws SQLException;
         default <V> SQLFindFunction<V, T> compose(Function<? super V, ? extends K> before) throws SQLException {
             Objects.requireNonNull(before);
             return (v) -> this.apply(before.apply(v));
         }
         default <V> SQLFindFunction<K, V> andThen(Function<? super T, ? extends V> after) throws SQLException {
             Objects.requireNonNull(after);
             return (t) -> after.apply(this.apply(t));
         }
         static <K> Function<K, K> identity() {
             return (t) -> t;
         }
     }
     /**
      * Invocation mapping gathered from the {@link RequestMapping} annotations.
      * <p>
      * Paths in this map must always start with a leading slash, although
      * the specification in the annotation must not start with a leading slash.
      * <p>
      * The reason for this is the different handling of empty paths in
      * {@link HttpServletRequest#getPathInfo()}.
      */
     private final Map<HttpMethod, Map<String, Method>> mappings = new HashMap<>();
     private final List<MenuEntry> subMenu = new ArrayList<>();
     /**
      * Gives implementing modules access to the {@link ModuleManager}.
      *
      * @return the module manager
      */
     protected final ModuleManager getModuleManager() {
         return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
     }
     /**
      * Creates a set of data access objects for the specified connection.
      *
      * @param connection the SQL connection
      * @return a set of data access objects
      */
     private DataAccessObjects createDataAccessObjects(Connection connection) throws SQLException {
         final var df = (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
         if (df.getSQLDialect() == DatabaseFacade.Dialect.Postgres) {
             return new PGDataAccessObjects(connection);
         }
         throw new AssertionError("Non-exhaustive if-else - this is a bug.");
     }
     private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp, DataAccessObjects dao) throws IOException {
         try {
             LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
             final var paramTypes = method.getParameterTypes();
             final var paramValues = new Object[paramTypes.length];
             for (int i = 0; i < paramTypes.length; i++) {
                 if (paramTypes[i].isAssignableFrom(HttpServletRequest.class)) {
                     paramValues[i] = req;
                 } else if (paramTypes[i].isAssignableFrom(HttpServletResponse.class)) {
                     paramValues[i] = resp;
                 }
                 if (paramTypes[i].isAssignableFrom(DataAccessObjects.class)) {
                     paramValues[i] = dao;
                 }
             }
             return (ResponseType) method.invoke(this, paramValues);
         } catch (ReflectiveOperationException | ClassCastException ex) {
             LOG.error("invocation of method {} failed: {}", method.getName(), ex.getMessage());
             LOG.debug("Details: ", 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))
                 .map(LightPITModule.ELProxy::new).orElse(null);
         if (moduleInfo != null) {
             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;
                     }
                     boolean paramsInjectible = true;
                     for (var param : method.getParameterTypes()) {
                         paramsInjectible &= HttpServletRequest.class.isAssignableFrom(param)
                                 || HttpServletResponse.class.isAssignableFrom(param)
                                 || DataAccessObjects.class.isAssignableFrom(param);
                     }
                     if (paramsInjectible) {
                         String requestPath = "/" + mapping.get().requestPath();
                         if (!mapping.get().requestPath().isBlank() && !mapping.get().menuKey().isBlank()) {
                             requestPath += "/";
                         }
                         if (mappings
                                 .computeIfAbsent(mapping.get().method(), k -> new HashMap<>())
                                 .putIfAbsent(requestPath, method) != null) {
                             LOG.warn("{} {} has multiple mappings",
                                     mapping.get().method(),
                                     mapping.get().requestPath()
                             );
                         }
                         final var menuKey = mapping.get().menuKey();
                         if (!menuKey.isBlank()) {
                             subMenu.add(new MenuEntry(
                                     new ResourceKey(moduleInfo.getBundleBaseName(), menuKey),
                                     moduleInfo.getModulePath() + requestPath,
                                     mapping.get().menuSequence()));
                         }
                         LOG.debug("{} {} maps to {}::{}",
                                 mapping.get().method(),
                                 requestPath,
                                 getClass().getSimpleName(),
                                 method.getName()
                         );
                     } else {
                         LOG.warn("{} is annotated with {} but has the wrong parameters - only HttpServletRequest. HttpServletResponse, and DataAccessObjects are allowed",
                                 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 the name of the dynamic fragment.
      * <p>
      * It is sufficient to specify the name without any extension. The extension
      * is added automatically if not specified.
      * <p>
      * The fragment must be located in the dynamic fragments folder.
      *
      * @param req          the servlet request object
      * @param fragmentName the name of the fragment
      * @see Constants#DYN_FRAGMENT_PATH_PREFIX
      */
     protected void setDynamicFragment(HttpServletRequest req, String fragmentName) {
         req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
     }
     /**
      * @param req      the servlet request object
      * @param location the location where to redirect
      * @see Constants#REQ_ATTR_REDIRECT_LOCATION
      */
     protected void setRedirectLocation(HttpServletRequest req, String location) {
         if (location.startsWith("./")) {
             location = location.replaceFirst("\\./", Functions.baseHref(req));
         }
         req.setAttribute(Constants.REQ_ATTR_REDIRECT_LOCATION, location);
     }
     /**
      * Specifies the name of an additional stylesheet used by the module.
      * <p>
      * Setting an additional stylesheet is optional, but quite common for HTML
      * output.
      * <p>
      * It is sufficient to specify the name without any extension. The extension
      * is added automatically if not specified.
      *
      * @param req        the servlet request object
      * @param stylesheet the name of the stylesheet
      */
     public void setStylesheet(HttpServletRequest req, String stylesheet) {
         req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
     }
     /**
      * Obtains a request parameter of the specified type.
      * The specified type must have a single-argument constructor accepting a string to perform conversion.
      * The constructor of the specified type may throw an exception on conversion failures.
      *
      * @param req the servlet request object
      * @param clazz the class object of the expected type
      * @param name the name of the parameter
      * @param <T> the expected type
      * @return the parameter value or an empty optional, if no parameter with the specified name was found
      */
     protected<T> Optional<T> getParameter(HttpServletRequest req, Class<T> clazz, String name) {
         final String paramValue = req.getParameter(name);
         if (paramValue == null) return Optional.empty();
         if (clazz.equals(String.class)) return Optional.of((T)paramValue);
         try {
             final Constructor<T> ctor = clazz.getConstructor(String.class);
             return Optional.of(ctor.newInstance(paramValue));
         } catch (ReflectiveOperationException e) {
             throw new RuntimeException(e);
         }
     }
     /**
      * Tries to look up an entity with a key obtained from a request parameter.
      *
      * @param req the servlet request object
      * @param clazz the class representing the type of the request parameter
      * @param name the name of the request parameter
      * @param find the find function (typically a DAO function)
      * @param <T> the type of the request parameter
      * @param <R> the type of the looked up entity
      * @return the retrieved entity or an empty optional if there is no such entity or the request parameter was missing
      * @throws SQLException if the find function throws an exception
      */
     protected<T,R> Optional<R> findByParameter(HttpServletRequest req, Class<T> clazz, String name, SQLFindFunction<? super T, ? extends R> find) throws SQLException {
         final var param = getParameter(req, clazz, name);
         if (param.isPresent()) {
             return Optional.ofNullable(find.apply(param.get()));
         } else {
             return Optional.empty();
         }
     }
     private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
             throws IOException, ServletException {
         req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
         req.setAttribute(Constants.REQ_ATTR_SUB_MENU, subMenu);
         req.getRequestDispatcher(SITE_JSP).forward(req, resp);
     }
     private String sanitizeRequestPath(HttpServletRequest req) {
         return Optional.ofNullable(req.getPathInfo()).orElse("/");
     }
     private Optional<Method> findMapping(HttpMethod method, HttpServletRequest req) {
         return Optional.ofNullable(mappings.get(method)).map(rm -> rm.get(sanitizeRequestPath(req)));
     }
     private void forwardAsSpecified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         switch (type) {
             case NONE:
                 return;
             case HTML:
                 forwardToFullView(req, resp);
                 return;
             // TODO: implement remaining response types
             default:
                 throw new AssertionError("ResponseType switch is not exhaustive - this is a bug!");
         }
     }
     private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         // choose the requested language as session language (if available) or fall back to english, otherwise
         HttpSession session = req.getSession();
         if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
             Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
             Optional<Locale> reqLocale = Optional.of(req.getLocale());
             Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
             session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
             LOG.debug("Setting language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
         } else {
             Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
             resp.setLocale(sessionLocale);
             LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
         }
         // set some internal request attributes
         final String fullPath = Functions.fullPath(req);
         req.setAttribute(Constants.REQ_ATTR_BASE_HREF, Functions.baseHref(req));
         req.setAttribute(Constants.REQ_ATTR_PATH, fullPath);
         Optional.ofNullable(moduleInfo).ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
         // if this is an error path, bypass the normal flow
         if (fullPath.startsWith("/error/")) {
             final var mapping = findMapping(method, req);
             if (mapping.isPresent()) {
                 forwardAsSpecified(invokeMapping(mapping.get(), req, resp, null), req, resp);
             }
             return;
         }
         // obtain a connection and create the data access objects
         final var db = (DatabaseFacade) req.getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
         final var ds = db.getDataSource();
         if (ds == null) {
             resp.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, "JNDI DataSource lookup failed. See log for details.");
             return;
         }
         try (final var connection = ds.getConnection()) {
             final var dao = createDataAccessObjects(connection);
             try {
                 connection.setAutoCommit(false);
                 // call the handler, if available, or send an HTTP 404 error
                 final var mapping = findMapping(method, req);
                 if (mapping.isPresent()) {
                     forwardAsSpecified(invokeMapping(mapping.get(), req, resp, dao), req, resp);
                 } else {
                     resp.sendError(HttpServletResponse.SC_NOT_FOUND);
                 }
                 connection.commit();
             } catch (SQLException ex) {
                 LOG.warn("Database transaction failed (Code {}): {}", ex.getErrorCode(), ex.getMessage());
                 LOG.debug("Details: ", ex);
                 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Unhandled Transaction Error - Code: " + ex.getErrorCode());
                 connection.rollback();
             }
         } catch (SQLException ex) {
             LOG.error("Severe Database Exception (Code {}): {}", ex.getErrorCode(), ex.getMessage());
             LOG.debug("Details: ", ex);
             resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Database Error - Code: " + ex.getErrorCode());
         }
     }
     @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/main/java/de/uapcore/lightpit/AbstractLightPITServlet.java@51aa5e267c7f (annotated)

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