org.springframework.boot.web.SpringBootServletInitializer.java Source code

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Here is the source code for org.springframework.boot.web.SpringBootServletInitializer.java

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/*
 * Copyright 2012-2013 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;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
import org.springframework.boot.context.initializer.ParentContextApplicationContextInitializer;
import org.springframework.boot.context.initializer.ServletContextApplicationContextInitializer;
import org.springframework.context.ApplicationContext;
import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.WebApplicationContext;

/**
 * A handy opinionated {@link WebApplicationInitializer} for applications that only have
 * one Spring servlet, and no more than a single filter (which itself is only enabled when
 * Spring Security is detected). If your application is more complicated consider using
 * one of the other WebApplicationInitializers.
 * 
 * <p/>
 * Note that a WebApplicationInitializer is only needed if you are building a war file and
 * deploying it. If you prefer to run an embedded container (we do) then you won't need
 * this at all.
 * 
 * @author Dave Syer
 */
public abstract class SpringBootServletInitializer implements WebApplicationInitializer {

    protected final Log logger = LogFactory.getLog(getClass());

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        WebApplicationContext rootAppContext = this.createRootApplicationContext(servletContext);
        if (rootAppContext != null) {
            servletContext.addListener(new ContextLoaderListener(rootAppContext) {
                @Override
                public void contextInitialized(ServletContextEvent event) {
                    // no-op because the application context is already initialized
                }
            });
        } else {
            this.logger.debug("No ContextLoaderListener registered, as " + "createRootApplicationContext() did not "
                    + "return an application context");
        }
    }

    protected WebApplicationContext createRootApplicationContext(ServletContext servletContext) {
        ApplicationContext parent = null;
        Object object = servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
        if (object instanceof ApplicationContext) {
            this.logger.info("Root context already created (using as parent).");
            parent = (ApplicationContext) object;
            servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
        }
        SpringApplicationBuilder application = new SpringApplicationBuilder();
        if (parent != null) {
            application.initializers(new ParentContextApplicationContextInitializer(parent));
        }
        application.initializers(new ServletContextApplicationContextInitializer(servletContext));
        application.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
        application = configure(application);
        return (WebApplicationContext) application.run();
    }

    /**
     * Configure the application. Normally all you would need to do it add sources (e.g.
     * config classes) because other settings have sensible defaults. You might choose
     * (for instance) to add default command line arguments, or set an active Spring
     * profile.
     * 
     * @param application a builder for the application context
     * @see SpringApplicationBuilder
     */
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application;
    }

}