Java tutorial
/** * This file is part of lavagna. * * lavagna is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * lavagna is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with lavagna. If not, see <http://www.gnu.org/licenses/>. */ package io.lavagna.common; import org.apache.commons.lang3.StringUtils; import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.core.env.MapPropertySource; import org.springframework.core.io.UrlResource; import org.springframework.core.io.support.ResourcePropertySource; import java.io.IOException; import java.util.Collections; import java.util.Map; public class LavagnaEnvironment { private final ConfigurableEnvironment environment; private static final String LAVAGNA_CONFIG_LOCATION = "lavagna.config.location"; private static final Logger LOG = LogManager.getLogger(); public LavagnaEnvironment(ConfigurableEnvironment environment) { this.environment = environment; if (environment.containsProperty(LAVAGNA_CONFIG_LOCATION) && StringUtils.isNotBlank(environment.getProperty(LAVAGNA_CONFIG_LOCATION))) { String configLocation = environment.getProperty(LAVAGNA_CONFIG_LOCATION); LOG.info("Detected config file {}, loading it", configLocation); try { environment.getPropertySources() .addFirst(new ResourcePropertySource(new UrlResource(configLocation))); } catch (IOException ioe) { throw new IllegalStateException( "error while loading external configuration file at " + configLocation, ioe); } } setSystemPropertyIfNull(environment, "datasource.dialect", "HSQLDB"); setSystemPropertyIfNull(environment, "datasource.url", "jdbc:hsqldb:mem:lavagna"); setSystemPropertyIfNull(environment, "datasource.username", "sa"); setSystemPropertyIfNull(environment, "datasource.password", ""); setSystemPropertyIfNull(environment, "spring.profiles.active", "dev"); logUse("datasource.dialect"); logUse("datasource.url"); logUse("datasource.username"); logUse("spring.profiles.active"); } private void logUse(String name) { LOG.info("For property {}, the value is: {}", name, environment.getProperty(name)); } private static void setSystemPropertyIfNull(ConfigurableEnvironment env, String name, String value) { if (!env.containsProperty(name) || StringUtils.isBlank(env.getProperty(name))) { LOG.warn("Property {} is not set, using default value: {}", name, value); Map<String, Object> source = Collections.singletonMap(name, (Object) value); env.getPropertySources().addFirst(new MapPropertySource(name, source)); } } public String getProperty(String key) { return environment.getProperty(key); } public boolean containsProperty(String key) { return environment.containsProperty(key); } public String getRequiredProperty(String key) { return environment.getRequiredProperty(key); } public String[] getActiveProfiles() { return environment.getActiveProfiles(); } }