org.springframework.web.server.adapter.AbstractReactiveWebInitializer Maven / Gradle / Ivy
/*
* 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
*
* 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.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 {@link org.springframework.web.WebApplicationInitializer}
* that installs a Spring Reactive Web Application on a Servlet container.
*
* 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 {@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 {@link ServletHttpHandlerAdapter}.
*
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 {@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 {@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.
*/
protected void refreshApplicationContext(ApplicationContext context) {
if (context instanceof ConfigurableApplicationContext) {
ConfigurableApplicationContext cac = (ConfigurableApplicationContext) context;
if (!cac.isActive()) {
cac.refresh();
}
}
}
/**
* 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 '/'.
*/
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();
}
}
}