ConfigurationProviderManager.java

/**
 * Copyright 2012 Sven Diedrichsen 
 * 
 * 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 de.jollyday.configuration;

import java.util.Properties;
import java.util.logging.Logger;

import de.jollyday.ManagerParameter;
import de.jollyday.configuration.impl.DefaultConfigurationProvider;
import de.jollyday.configuration.impl.URLConfigurationProvider;
import de.jollyday.util.ClassLoadingUtil;

/**
 * Manages the configuration provider implementations and thus delivering the
 * jollyday configuration.
 * 
 * @author sven
 */
public class ConfigurationProviderManager {

	private static final Logger LOG = Logger.getLogger(ConfigurationProviderManager.class.getName());

	private ConfigurationProvider defaultConfigurationProvider = new DefaultConfigurationProvider();
	private ConfigurationProvider urlConfigurationProvider = new URLConfigurationProvider();
	private transient ClassLoadingUtil classLoadingUtil = new ClassLoadingUtil();

	/**
	 * Constructs an instance
	 */
	public ConfigurationProviderManager() {
	}

	/**
	 * Reads the jollyday configuration from the
	 * {@link DefaultConfigurationProvider}, the
	 * {@link URLConfigurationProvider} and any configuration provider specified
	 * by the system property 'de.jollyday.config.provider'.
	 * 
	 * @param parameter
	 *            the configuration {@link ManagerParameter} to use
	 */
	public void mergeConfigurationProperties(ManagerParameter parameter) {
		addInternalConfigurationProviderProperies(parameter);
		addCustomConfigurationProviderProperties(parameter);
	}

	private void addInternalConfigurationProviderProperies(ManagerParameter parameter) {
		parameter.mergeProperties(urlConfigurationProvider.getProperties());
		parameter.mergeProperties(defaultConfigurationProvider.getProperties());
	}

	private void addCustomConfigurationProviderProperties(ManagerParameter parameter) {
		Properties systemProps = System.getProperties();
		String providersStrList = systemProps.getProperty(ConfigurationProvider.CONFIG_PROVIDERS_PROPERTY);
		if (providersStrList != null) {
			String[] providersClassNames = providersStrList.split(",");
			if (providersClassNames != null) {
				for (String providerClassName : providersClassNames) {
					if (providerClassName == null || "".equals(providerClassName))
						continue;
					try {
						Class<?> providerClass = Class.forName(providerClassName.trim(), true,
								classLoadingUtil.getClassloader());
						ConfigurationProvider configurationProvider = ConfigurationProvider.class.cast(providerClass
								.newInstance());
						parameter.mergeProperties(configurationProvider.getProperties());
					} catch (Exception e) {
						LOG.warning("Cannot load configuration from provider class '" + providerClassName + "'. "
								+ e.getClass().getSimpleName() + " (" + e.getMessage() + ").");
					}
				}
			}
		}
	}

}