Java tutorial
/* * Copyright 2002-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.servlet.config.annotation; import java.util.ArrayList; import java.util.Arrays; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import javax.servlet.ServletContext; import org.springframework.beans.factory.BeanInitializationException; import org.springframework.context.ApplicationContext; import org.springframework.core.Ordered; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.web.HttpRequestHandler; import org.springframework.web.accept.ContentNegotiationManager; import org.springframework.web.servlet.HandlerMapping; import org.springframework.web.servlet.handler.AbstractHandlerMapping; import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping; import org.springframework.web.servlet.resource.ResourceHttpRequestHandler; import org.springframework.web.util.UrlPathHelper; /** * Stores registrations of resource handlers for serving static resources such as images, css files and others * through Spring MVC including setting cache headers optimized for efficient loading in a web browser. * Resources can be served out of locations under web application root, from the classpath, and others. * * <p>To create a resource handler, use {@link #addResourceHandler(String...)} providing the URL path patterns * for which the handler should be invoked to serve static resources (e.g. {@code "/resources/**"}). * * <p>Then use additional methods on the returned {@link ResourceHandlerRegistration} to add one or more * locations from which to serve static content from (e.g. {{@code "/"}, * {@code "classpath:/META-INF/public-web-resources/"}}) or to specify a cache period for served resources. * * @author Rossen Stoyanchev * @since 3.1 * @see DefaultServletHandlerConfigurer */ public class ResourceHandlerRegistry { private final ServletContext servletContext; private final ApplicationContext applicationContext; @Nullable private final ContentNegotiationManager contentNegotiationManager; @Nullable private final UrlPathHelper pathHelper; private final List<ResourceHandlerRegistration> registrations = new ArrayList<>(); private int order = Ordered.LOWEST_PRECEDENCE - 1; /** * Create a new resource handler registry for the given application context. * @param applicationContext the Spring application context * @param servletContext the corresponding Servlet context */ public ResourceHandlerRegistry(ApplicationContext applicationContext, ServletContext servletContext) { this(applicationContext, servletContext, null); } /** * Create a new resource handler registry for the given application context. * @param applicationContext the Spring application context * @param servletContext the corresponding Servlet context * @param contentNegotiationManager the content negotiation manager to use * @since 4.3 */ public ResourceHandlerRegistry(ApplicationContext applicationContext, ServletContext servletContext, @Nullable ContentNegotiationManager contentNegotiationManager) { this(applicationContext, servletContext, contentNegotiationManager, null); } /** * A variant of * {@link #ResourceHandlerRegistry(ApplicationContext, ServletContext, ContentNegotiationManager)} * that also accepts the {@link UrlPathHelper} used for mapping requests to static resources. * @since 4.3.13 */ public ResourceHandlerRegistry(ApplicationContext applicationContext, ServletContext servletContext, @Nullable ContentNegotiationManager contentNegotiationManager, @Nullable UrlPathHelper pathHelper) { Assert.notNull(applicationContext, "ApplicationContext is required"); this.applicationContext = applicationContext; this.servletContext = servletContext; this.contentNegotiationManager = contentNegotiationManager; this.pathHelper = pathHelper; } /** * Add a resource handler for serving static resources based on the specified URL path patterns. * The handler will be invoked for every incoming request that matches to one of the specified * path patterns. * <p>Patterns like {@code "/static/**"} or {@code "/css/{filename:\\w+\\.css}"} are allowed. * See {@link org.springframework.util.AntPathMatcher} for more details on the syntax. * @return a {@link ResourceHandlerRegistration} to use to further configure the * registered resource handler */ public ResourceHandlerRegistration addResourceHandler(String... pathPatterns) { ResourceHandlerRegistration registration = new ResourceHandlerRegistration(pathPatterns); this.registrations.add(registration); return registration; } /** * Whether a resource handler has already been registered for the given path pattern. */ public boolean hasMappingForPattern(String pathPattern) { for (ResourceHandlerRegistration registration : this.registrations) { if (Arrays.asList(registration.getPathPatterns()).contains(pathPattern)) { return true; } } return false; } /** * Specify the order to use for resource handling relative to other {@link HandlerMapping HandlerMappings} * configured in the Spring MVC application context. * <p>The default value used is {@code Integer.MAX_VALUE-1}. */ public ResourceHandlerRegistry setOrder(int order) { this.order = order; return this; } /** * Return a handler mapping with the mapped resource handlers; or {@code null} in case * of no registrations. */ @Nullable protected AbstractHandlerMapping getHandlerMapping() { if (this.registrations.isEmpty()) { return null; } Map<String, HttpRequestHandler> urlMap = new LinkedHashMap<>(); for (ResourceHandlerRegistration registration : this.registrations) { for (String pathPattern : registration.getPathPatterns()) { ResourceHttpRequestHandler handler = registration.getRequestHandler(); if (this.pathHelper != null) { handler.setUrlPathHelper(this.pathHelper); } if (this.contentNegotiationManager != null) { handler.setContentNegotiationManager(this.contentNegotiationManager); } handler.setServletContext(this.servletContext); handler.setApplicationContext(this.applicationContext); try { handler.afterPropertiesSet(); } catch (Throwable ex) { throw new BeanInitializationException("Failed to init ResourceHttpRequestHandler", ex); } urlMap.put(pathPattern, handler); } } return new SimpleUrlHandlerMapping(urlMap, this.order); } }