Java tutorial
/* * Copyright 2011-2014 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.cloudfoundry.reconfiguration.util; import org.springframework.cloud.CloudException; import org.springframework.cloud.CloudFactory; import org.springframework.context.ApplicationContext; import org.springframework.core.io.Resource; import org.springframework.util.ClassUtils; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.HashSet; import java.util.Set; import java.util.logging.Logger; /** * Standard implementation of {@link CloudUtils} */ public final class StandardCloudUtils implements CloudUtils { private final Logger logger = Logger.getLogger(this.getClass().getName()); private final Object monitor = new Object(); private volatile CloudFactory cloudFactory; private volatile Boolean usingCloudServices; /** * Creates a new instance */ public StandardCloudUtils() { } StandardCloudUtils(CloudFactory cloudFactory) { this.cloudFactory = cloudFactory; } @Override public CloudFactory getCloudFactory() { synchronized (this.monitor) { if (this.cloudFactory == null) { this.cloudFactory = new CloudFactory(); } return this.cloudFactory; } } @Override public Boolean isInCloud() { try { getCloudFactory().getCloud(); return true; } catch (CloudException e) { return false; } } @Override public Boolean isUsingCloudServices(ApplicationContext applicationContext) { synchronized (this.monitor) { if (this.usingCloudServices == null) { this.usingCloudServices = calculateUsingCloudServices(applicationContext); } return this.usingCloudServices; } } private Boolean calculateUsingCloudServices(ApplicationContext applicationContext) { try { for (Resource resource : applicationContext.getResources("classpath*:/META-INF/cloud/cloud-services")) { for (String cloudServiceClass : getCloudServiceClasses(resource)) { if (hasBeanOfType(applicationContext, cloudServiceClass)) { return true; } } } } catch (IOException e) { this.logger.warning("Unable to read cloud service classes"); } return false; } private Boolean hasBeanOfType(ApplicationContext applicationContext, String cloudServiceClassName) { if (ClassUtils.isPresent(cloudServiceClassName, null)) { Class<?> cloudServiceClass = ClassUtils.resolveClassName(cloudServiceClassName, null); return applicationContext.getBeanNamesForType(cloudServiceClass, true, false).length != 0; } return false; } private Set<String> getCloudServiceClasses(Resource resource) { Set<String> cloudServiceClasses = new HashSet<String>(); BufferedReader in = null; try { in = new BufferedReader(new InputStreamReader(resource.getInputStream())); String line; while ((line = in.readLine()) != null) { cloudServiceClasses.add(line.trim()); } } catch (IOException e) { this.logger .warning(String.format("Unable to read cloud service classes from %s", resource.getFilename())); } finally { IoUtils.closeQuietly(in); } return cloudServiceClasses; } }