Java tutorial
package com.devicehive.service.configuration; /* * #%L * DeviceHive Java Server Common business logic * %% * Copyright (C) 2016 DataArt * %% * 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. * #L% */ import com.devicehive.configuration.Messages; import com.devicehive.dao.ConfigurationDao; import com.devicehive.vo.ConfigurationVO; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Lazy; import org.springframework.stereotype.Component; import javax.transaction.Transactional; import javax.validation.constraints.NotNull; import java.util.Optional; @Component @Lazy(false) public class ConfigurationService { private static final Logger logger = LoggerFactory.getLogger(ConfigurationService.class); @Autowired private ConfigurationDao configurationDao; @Transactional public <T> void save(@NotNull String name, T value) { //TODO check keys are same String str = value != null ? value.toString() : null; Optional<ConfigurationVO> existingOpt = findByName(name); if (existingOpt.isPresent()) { ConfigurationVO existing = existingOpt.get(); existing.setValue(str); configurationDao.merge(existing); } else { ConfigurationVO configuration = new ConfigurationVO(); configuration.setName(name); configuration.setValue(str); configurationDao.persist(configuration); } } private Optional<ConfigurationVO> findByName(String name) { return configurationDao.getByName(name); } public String get(@NotNull String name) { return findByName(name).map(ConfigurationVO::getValue).orElseGet(() -> { logger.warn(String.format(Messages.CONFIG_NOT_FOUND, name)); return null; }); } public long getLong(@NotNull String name, long defaultValue) { String val = get(name); return val != null ? Long.parseLong(val) : defaultValue; } public int getInt(@NotNull String name, int defaultValue) { String val = get(name); return val != null ? Integer.parseInt(val) : defaultValue; } public boolean getBoolean(@NotNull String name, boolean defaultValue) { String val = get(name); return val != null ? Boolean.parseBoolean(val) : defaultValue; } @Transactional public <T> void delete(@NotNull String name) { int result = configurationDao.delete(name); logger.info("Deleted {} configuration entries by name {}", result, name); } }