com.cimait.invoicec.portal.util.servlet.SBServletInitializer.java Source code

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/*
* Copyright 2012-2014 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 com.cimait.invoicec.portal.util.servlet;

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.ParentContextApplicationContextInitializer;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
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 starts a
 * Spring Boot application and lets it bind to the servlet and filter mappings. 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 SBServletInitializer implements WebApplicationInitializer {
    protected final Log logger = LogFactory.getLog(getClass());

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        WebApplicationContext rootAppContext = 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);
        // Ensure error pages are registered
        //application.sources(ErrorPageFilter.class);
        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;
    }
}