/*
 * Copyright 2002-2018 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
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package org.springframework.web.server.adapter;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.http.server.reactive.HttpHandler;
import org.springframework.http.server.reactive.ServletHttpHandlerAdapter;
import org.springframework.util.Assert;
import org.springframework.web.WebApplicationInitializer;

Base class for a WebApplicationInitializer that installs a Spring Reactive Web Application on a Servlet container.

Spring configuration is loaded and given to WebHttpHandlerBuilder which scans the context looking for specific beans and creates a reactive HttpHandler. The resulting handler is installed as a Servlet through the ServletHttpHandlerAdapter.

Author:Rossen Stoyanchev
Since:5.0.2
/** * Base class for a {@link org.springframework.web.WebApplicationInitializer} * that installs a Spring Reactive Web Application on a Servlet container. * * <p>Spring configuration is loaded and given to * {@link WebHttpHandlerBuilder#applicationContext WebHttpHandlerBuilder} * which scans the context looking for specific beans and creates a reactive * {@link HttpHandler}. The resulting handler is installed as a Servlet through * the {@link ServletHttpHandlerAdapter}. * * @author Rossen Stoyanchev * @since 5.0.2 */
public abstract class AbstractReactiveWebInitializer implements WebApplicationInitializer {
The default servlet name to use. See getServletName.
/** * The default servlet name to use. See {@link #getServletName}. */
public static final String DEFAULT_SERVLET_NAME = "http-handler-adapter"; @Override public void onStartup(ServletContext servletContext) throws ServletException { String servletName = getServletName(); Assert.hasLength(servletName, "getServletName() must not return null or empty"); ApplicationContext applicationContext = createApplicationContext(); Assert.notNull(applicationContext, "createApplicationContext() must not return null"); refreshApplicationContext(applicationContext); registerCloseListener(servletContext, applicationContext); HttpHandler httpHandler = WebHttpHandlerBuilder.applicationContext(applicationContext).build(); ServletHttpHandlerAdapter servlet = new ServletHttpHandlerAdapter(httpHandler); ServletRegistration.Dynamic registration = servletContext.addServlet(servletName, servlet); if (registration == null) { throw new IllegalStateException("Failed to register servlet with name '" + servletName + "'. " + "Check if there is another servlet registered under the same name."); } registration.setLoadOnStartup(1); registration.addMapping(getServletMapping()); registration.setAsyncSupported(true); }
Return the name to use to register the ServletHttpHandlerAdapter.

By default this is DEFAULT_SERVLET_NAME.

/** * Return the name to use to register the {@link ServletHttpHandlerAdapter}. * <p>By default this is {@link #DEFAULT_SERVLET_NAME}. */
protected String getServletName() { return DEFAULT_SERVLET_NAME; }
Return the Spring configuration that contains application beans including the ones detected by WebHttpHandlerBuilder.applicationContext.
/** * Return the Spring configuration that contains application beans including * the ones detected by {@link WebHttpHandlerBuilder#applicationContext}. */
protected ApplicationContext createApplicationContext() { AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(); Class<?>[] configClasses = getConfigClasses(); Assert.notEmpty(configClasses, "No Spring configuration provided through getConfigClasses()"); context.register(configClasses); return context; }
Specify @Configuration and/or @Component classes that make up the application configuration. The config classes are given to createApplicationContext().
/** * Specify {@link org.springframework.context.annotation.Configuration @Configuration} * and/or {@link org.springframework.stereotype.Component @Component} * classes that make up the application configuration. The config classes * are given to {@linkplain #createApplicationContext()}. */
protected abstract Class<?>[] getConfigClasses();
Refresh the given application context, if necessary.
/** * Refresh the given application context, if necessary. */
protected void refreshApplicationContext(ApplicationContext context) { if (context instanceof ConfigurableApplicationContext) { ConfigurableApplicationContext cac = (ConfigurableApplicationContext) context; if (!cac.isActive()) { cac.refresh(); } } }
Register a ServletContextListener that closes the given application context when the servlet context is destroyed.
Params:
  • servletContext – the servlet context to listen to
  • applicationContext – the application context that is to be closed when servletContext is destroyed
/** * Register a {@link ServletContextListener} that closes the given * application context when the servlet context is destroyed. * @param servletContext the servlet context to listen to * @param applicationContext the application context that is to be * closed when {@code servletContext} is destroyed */
protected void registerCloseListener(ServletContext servletContext, ApplicationContext applicationContext) { if (applicationContext instanceof ConfigurableApplicationContext) { ConfigurableApplicationContext cac = (ConfigurableApplicationContext) applicationContext; ServletContextDestroyedListener listener = new ServletContextDestroyedListener(cac); servletContext.addListener(listener); } }
Return the Servlet mapping to use. Only the default Servlet mapping '/' and path-based Servlet mappings such as '/api/*' are supported.

By default this is set to '/'.

/** * Return the Servlet mapping to use. Only the default Servlet mapping '/' * and path-based Servlet mappings such as '/api/*' are supported. * <p>By default this is set to '/'. */
protected String getServletMapping() { return "/"; } private static class ServletContextDestroyedListener implements ServletContextListener { private final ConfigurableApplicationContext applicationContext; public ServletContextDestroyedListener(ConfigurableApplicationContext applicationContext) { this.applicationContext = applicationContext; } @Override public void contextInitialized(ServletContextEvent sce) { } @Override public void contextDestroyed(ServletContextEvent sce) { this.applicationContext.close(); } } }