Java tutorial
/* * Copyright 2012-2018 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 * * http://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.boot.web.servlet.context; import java.util.Collection; import java.util.Collections; import java.util.EventListener; import java.util.HashMap; import java.util.LinkedHashSet; import java.util.Map; import java.util.Set; import javax.servlet.Filter; import javax.servlet.Servlet; import javax.servlet.ServletConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.config.Scope; import org.springframework.beans.factory.support.DefaultListableBeanFactory; import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext; import org.springframework.boot.web.server.WebServer; import org.springframework.boot.web.servlet.FilterRegistrationBean; import org.springframework.boot.web.servlet.ServletContextInitializer; import org.springframework.boot.web.servlet.ServletContextInitializerBeans; import org.springframework.boot.web.servlet.ServletRegistrationBean; import org.springframework.boot.web.servlet.server.ServletWebServerFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextException; import org.springframework.core.io.Resource; import org.springframework.util.StringUtils; import org.springframework.web.context.ContextLoader; import org.springframework.web.context.ContextLoaderListener; import org.springframework.web.context.ServletContextAware; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.support.GenericWebApplicationContext; import org.springframework.web.context.support.ServletContextAwareProcessor; import org.springframework.web.context.support.ServletContextResource; import org.springframework.web.context.support.WebApplicationContextUtils; /** * A {@link WebApplicationContext} that can be used to bootstrap itself from a contained * {@link ServletWebServerFactory} bean. * <p> * This context will create, initialize and run an {@link WebServer} by searching for a * single {@link ServletWebServerFactory} bean within the {@link ApplicationContext} * itself. The {@link ServletWebServerFactory} is free to use standard Spring concepts * (such as dependency injection, lifecycle callbacks and property placeholder variables). * <p> * In addition, any {@link Servlet} or {@link Filter} beans defined in the context will be * automatically registered with the web server. In the case of a single Servlet bean, the * '/' mapping will be used. If multiple Servlet beans are found then the lowercase bean * name will be used as a mapping prefix. Any Servlet named 'dispatcherServlet' will * always be mapped to '/'. Filter beans will be mapped to all URLs ('/*'). * <p> * For more advanced configuration, the context can instead define beans that implement * the {@link ServletContextInitializer} interface (most often * {@link ServletRegistrationBean}s and/or {@link FilterRegistrationBean}s). To prevent * double registration, the use of {@link ServletContextInitializer} beans will disable * automatic Servlet and Filter bean registration. * <p> * Although this context can be used directly, most developers should consider using the * {@link AnnotationConfigServletWebServerApplicationContext} or * {@link XmlServletWebServerApplicationContext} variants. * * @author Phillip Webb * @author Dave Syer * @see AnnotationConfigServletWebServerApplicationContext * @see XmlServletWebServerApplicationContext * @see ServletWebServerFactory */ public class ServletWebServerApplicationContext extends GenericWebApplicationContext implements ConfigurableWebServerApplicationContext { private static final Log logger = LogFactory.getLog(ServletWebServerApplicationContext.class); /** * Constant value for the DispatcherServlet bean name. A Servlet bean with this name * is deemed to be the "main" servlet and is automatically given a mapping of "/" by * default. To change the default behavior you can use a * {@link ServletRegistrationBean} or a different bean name. */ public static final String DISPATCHER_SERVLET_NAME = "dispatcherServlet"; private volatile WebServer webServer; private ServletConfig servletConfig; private String serverNamespace; /** * Create a new {@link ServletWebServerApplicationContext}. */ public ServletWebServerApplicationContext() { } /** * Create a new {@link ServletWebServerApplicationContext} with the given * {@code DefaultListableBeanFactory}. * @param beanFactory the DefaultListableBeanFactory instance to use for this context */ public ServletWebServerApplicationContext(DefaultListableBeanFactory beanFactory) { super(beanFactory); } /** * Register ServletContextAwareProcessor. * @see ServletContextAwareProcessor */ @Override protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this)); beanFactory.ignoreDependencyInterface(ServletContextAware.class); } @Override public final void refresh() throws BeansException, IllegalStateException { try { super.refresh(); } catch (RuntimeException ex) { stopAndReleaseWebServer(); throw ex; } } @Override protected void onRefresh() { super.onRefresh(); try { createWebServer(); } catch (Throwable ex) { throw new ApplicationContextException("Unable to start web server", ex); } } @Override protected void finishRefresh() { super.finishRefresh(); WebServer webServer = startWebServer(); if (webServer != null) { publishEvent(new ServletWebServerInitializedEvent(webServer, this)); } } @Override protected void onClose() { super.onClose(); stopAndReleaseWebServer(); } private void createWebServer() { WebServer webServer = this.webServer; ServletContext servletContext = getServletContext(); if (webServer == null && servletContext == null) { ServletWebServerFactory factory = getWebServerFactory(); this.webServer = factory.getWebServer(getSelfInitializer()); } else if (servletContext != null) { try { getSelfInitializer().onStartup(servletContext); } catch (ServletException ex) { throw new ApplicationContextException("Cannot initialize servlet context", ex); } } initPropertySources(); } /** * Returns the {@link ServletWebServerFactory} that should be used to create the * embedded {@link WebServer}. By default this method searches for a suitable bean in * the context itself. * @return a {@link ServletWebServerFactory} (never {@code null}) */ protected ServletWebServerFactory getWebServerFactory() { // Use bean names so that we don't consider the hierarchy String[] beanNames = getBeanFactory().getBeanNamesForType(ServletWebServerFactory.class); if (beanNames.length == 0) { throw new ApplicationContextException( "Unable to start ServletWebServerApplicationContext due to missing " + "ServletWebServerFactory bean."); } if (beanNames.length > 1) { throw new ApplicationContextException( "Unable to start ServletWebServerApplicationContext due to multiple " + "ServletWebServerFactory beans : " + StringUtils.arrayToCommaDelimitedString(beanNames)); } return getBeanFactory().getBean(beanNames[0], ServletWebServerFactory.class); } /** * Returns the {@link ServletContextInitializer} that will be used to complete the * setup of this {@link WebApplicationContext}. * @return the self initializer * @see #prepareWebApplicationContext(ServletContext) */ private org.springframework.boot.web.servlet.ServletContextInitializer getSelfInitializer() { return this::selfInitialize; } private void selfInitialize(ServletContext servletContext) throws ServletException { prepareWebApplicationContext(servletContext); ConfigurableListableBeanFactory beanFactory = getBeanFactory(); ExistingWebApplicationScopes existingScopes = new ExistingWebApplicationScopes(beanFactory); WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, getServletContext()); existingScopes.restore(); WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, getServletContext()); for (ServletContextInitializer beans : getServletContextInitializerBeans()) { beans.onStartup(servletContext); } } /** * Returns {@link ServletContextInitializer}s that should be used with the embedded * web server. By default this method will first attempt to find * {@link ServletContextInitializer}, {@link Servlet}, {@link Filter} and certain * {@link EventListener} beans. * @return the servlet initializer beans */ protected Collection<ServletContextInitializer> getServletContextInitializerBeans() { return new ServletContextInitializerBeans(getBeanFactory()); } /** * Prepare the {@link WebApplicationContext} with the given fully loaded * {@link ServletContext}. This method is usually called from * {@link ServletContextInitializer#onStartup(ServletContext)} and is similar to the * functionality usually provided by a {@link ContextLoaderListener}. * @param servletContext the operational servlet context */ protected void prepareWebApplicationContext(ServletContext servletContext) { Object rootContext = servletContext .getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE); if (rootContext != null) { if (rootContext == this) { throw new IllegalStateException( "Cannot initialize context because there is already a root application context present - " + "check whether you have multiple ServletContextInitializers!"); } return; } Log logger = LogFactory.getLog(ContextLoader.class); servletContext.log("Initializing Spring embedded WebApplicationContext"); try { servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this); if (logger.isDebugEnabled()) { logger.debug("Published root WebApplicationContext as ServletContext attribute with name [" + WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE + "]"); } setServletContext(servletContext); if (logger.isInfoEnabled()) { long elapsedTime = System.currentTimeMillis() - getStartupDate(); logger.info("Root WebApplicationContext: initialization completed in " + elapsedTime + " ms"); } } catch (RuntimeException | Error ex) { logger.error("Context initialization failed", ex); servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex); throw ex; } } private WebServer startWebServer() { WebServer webServer = this.webServer; if (webServer != null) { webServer.start(); } return webServer; } private void stopAndReleaseWebServer() { WebServer webServer = this.webServer; if (webServer != null) { try { webServer.stop(); this.webServer = null; } catch (Exception ex) { throw new IllegalStateException(ex); } } } @Override protected Resource getResourceByPath(String path) { if (getServletContext() == null) { return new ClassPathContextResource(path, getClassLoader()); } return new ServletContextResource(getServletContext(), path); } @Override public String getServerNamespace() { return this.serverNamespace; } @Override public void setServerNamespace(String serverNamespace) { this.serverNamespace = serverNamespace; } @Override public void setServletConfig(ServletConfig servletConfig) { this.servletConfig = servletConfig; } @Override public ServletConfig getServletConfig() { return this.servletConfig; } /** * Returns the {@link WebServer} that was created by the context or {@code null} if * the server has not yet been created. * @return the embedded web server */ @Override public WebServer getWebServer() { return this.webServer; } /** * Utility class to store and restore any user defined scopes. This allow scopes to be * registered in an ApplicationContextInitializer in the same way as they would in a * classic non-embedded web application context. */ public static class ExistingWebApplicationScopes { private static final Set<String> SCOPES; static { Set<String> scopes = new LinkedHashSet<>(); scopes.add(WebApplicationContext.SCOPE_REQUEST); scopes.add(WebApplicationContext.SCOPE_SESSION); SCOPES = Collections.unmodifiableSet(scopes); } private final ConfigurableListableBeanFactory beanFactory; private final Map<String, Scope> scopes = new HashMap<>(); public ExistingWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) { this.beanFactory = beanFactory; for (String scopeName : SCOPES) { Scope scope = beanFactory.getRegisteredScope(scopeName); if (scope != null) { this.scopes.put(scopeName, scope); } } } public void restore() { this.scopes.forEach((key, value) -> { if (logger.isInfoEnabled()) { logger.info("Restoring user defined scope " + key); } this.beanFactory.registerScope(key, value); }); } } }