ProfileContextInitializer.java

package de.neosit.spring.context;

import java.io.IOException;

import javax.servlet.ServletContext;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.AbstractEnvironment;
import org.springframework.core.io.support.ResourcePropertySource;
import org.springframework.util.StringUtils;
import org.springframework.web.context.support.XmlWebApplicationContext;

/**
 * This context enables the selection of profiles which were introduced with
 * Spring 3.1. The primary idea behind this class came from Alex Radzin /
 * {@link http 
 * ://alexradzin.blogspot.de/2012/04/initiate-current-spring-profile-from .html}
 * .
 * 
 * You have to use the following context parameter inside your web.xml to enable
 * this initializer:
 * 
 * <pre>
 * &lt;context-param&gt;
 *   	&lt;param-name&gt;contextInitializerClasses&lt;/param-name&gt;
 * 		&lt;param-value&gt;de.neosit.spring.context.ProfileContextInitializer&lt;/param-value&gt;
 * &lt;/context-param&gt;
 * </pre>
 * 
 * <strong>Order</strong>
 * <ul>
 * <li>If application was started with -Dspring.profiles.active, do nothing.</li>
 * <li>Lookup {@value #USE_SPRING_PROFILE_PROPERTY} inside web.xml's
 * context-param tag. If it does exist, use the defined value active profile.</li>
 * <li>If no {@value #USE_SPRING_PROFILE_PROPERTY} is given, lookup
 * context-param {@value #LOAD_PROPERTY_FILE} inside the web.xml. If it does
 * exist, load the resource(s). One of the resources should contain
 * <em>spring.profiles.active</em> parameter. The value behind this parameter
 * can be dynamically replaced with Maven or Ant during the build process.</li>
 * <li>If no {@value #LOAD_PROPERTY_FILE} is defined, the resource
 * "classpath:profile.properties" will be included. The initializer throws a
 * {@link RuntimeException} if it does not exist.</li>
 * </ul>
 * 
 * @author Christopher Klein
 * 
 */
public class ProfileContextInitializer implements
		ApplicationContextInitializer<ConfigurableApplicationContext> {

	Logger log = LoggerFactory.getLogger(ProfileContextInitializer.class);

	public final static String DEFAULT_PROFILE_PROPERTY_FILE = "classpath:profile/active.properties";

	public final static String USE_SPRING_PROFILE_PROPERTY = "useSpringProfile";

	public final static String LOAD_PROPERTY_FILE = "additionalPropertySources";

	public void initialize(ConfigurableApplicationContext applicationContext) {
		log.info("Initializing profile context");
		String additionalPropertySources = System
				.getProperty(LOAD_PROPERTY_FILE);

		String profilesSysProp = System
				.getProperty(AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME);

		if (!StringUtils.isEmpty(profilesSysProp)) {
			log.info("Spring profile was selected by global configuration parameter (active Spring profiles: "
					+ profilesSysProp + ")");
			return;
		}

		if (applicationContext.getClass().isAssignableFrom(
				XmlWebApplicationContext.class)) {
			ServletContext ctx = ((XmlWebApplicationContext) applicationContext)
					.getServletContext();

			String profile = ctx.getInitParameter(USE_SPRING_PROFILE_PROPERTY);

			if (!StringUtils.isEmpty(profile)) {
				log.info("Spring profile selected by web.xml configuration setting "
						+ USE_SPRING_PROFILE_PROPERTY
						+ " (active Spring profiles: " + profile + ")");
				applicationContext.getEnvironment().setActiveProfiles(profile);
				return;
			}

			String overrideAdditionalPropertySources = ctx
					.getInitParameter(LOAD_PROPERTY_FILE);

			if (!StringUtils.isEmpty(overrideAdditionalPropertySources)) {
				log.info("Loading additional property files by web.xml configuration setting "
						+ LOAD_PROPERTY_FILE
						+ ". This file should contain the spring.profiles.active parameter.");
				additionalPropertySources = overrideAdditionalPropertySources;
			}
		}

		if (StringUtils.isEmpty(additionalPropertySources)) {
			log.warn("No additional property sources defined. Falling back to "
					+ DEFAULT_PROFILE_PROPERTY_FILE);
			additionalPropertySources = DEFAULT_PROFILE_PROPERTY_FILE;
		}

		try {
			log.info("Loading additional property sources from "
					+ additionalPropertySources);

			ResourcePropertySource propertySource = new ResourcePropertySource(
					additionalPropertySources);

			Object assignedProfile = propertySource
					.getProperty(AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME);

			if (StringUtils.isEmpty(assignedProfile)) {
				log.warn("None of the defined property source from "
						+ additionalPropertySources + " contains "
						+ AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME);
			} else {
				log.info("One of the additional property sources contained "
						+ AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME
						+ " (active Spring profiles: "
						+ (String) assignedProfile + ")");

				// prevent circular resolvement
				if (((String) assignedProfile).startsWith("${")) {
					throw new RuntimeException(
							"The profile file "
									+ additionalPropertySources
									+ " contains a profile statement but this is invalid as it although uses Spring EL ("
									+ assignedProfile
									+ "). Please check your Maven build process that the environment variable has been correctly replaced.");
				}
			}

			applicationContext.getEnvironment().getPropertySources()
					.addFirst(propertySource);
		} catch (IOException e) {
			log.error("Unable to load property source "
					+ additionalPropertySources, e);
			throw new RuntimeException(e);
		}
	}
}