Java tutorial
/* * Copyright 2012-2018 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 * * 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.context.properties; import java.util.Map; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.PropertySourcesPlaceholderConfigurer; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.core.env.Environment; import org.springframework.core.env.MutablePropertySources; import org.springframework.core.env.PropertySources; /** * Utility to deduce the {@link PropertySources} to use for configuration binding. * * @author Phillip Webb */ class PropertySourcesDeducer { private static final Log logger = LogFactory.getLog(PropertySourcesDeducer.class); private final ApplicationContext applicationContext; PropertySourcesDeducer(ApplicationContext applicationContext) { this.applicationContext = applicationContext; } public PropertySources getPropertySources() { PropertySourcesPlaceholderConfigurer configurer = getSinglePropertySourcesPlaceholderConfigurer(); if (configurer != null) { return configurer.getAppliedPropertySources(); } MutablePropertySources sources = extractEnvironmentPropertySources(); if (sources != null) { return sources; } throw new IllegalStateException( "Unable to obtain PropertySources from " + "PropertySourcesPlaceholderConfigurer or Environment"); } private MutablePropertySources extractEnvironmentPropertySources() { Environment environment = this.applicationContext.getEnvironment(); if (environment instanceof ConfigurableEnvironment) { return ((ConfigurableEnvironment) environment).getPropertySources(); } return null; } private PropertySourcesPlaceholderConfigurer getSinglePropertySourcesPlaceholderConfigurer() { // Take care not to cause early instantiation of all FactoryBeans Map<String, PropertySourcesPlaceholderConfigurer> beans = this.applicationContext .getBeansOfType(PropertySourcesPlaceholderConfigurer.class, false, false); if (beans.size() == 1) { return beans.values().iterator().next(); } if (beans.size() > 1 && logger.isWarnEnabled()) { logger.warn("Multiple PropertySourcesPlaceholderConfigurer " + "beans registered " + beans.keySet() + ", falling back to Environment"); } return null; } }