Java tutorial
/* * Druid - a distributed column store. * Copyright 2012 - 2015 Metamarkets Group Inc. * * 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 io.druid.common.aws; import com.amazonaws.auth.AWSCredentialsProvider; public class LazyFileSessionCredentialsProvider implements AWSCredentialsProvider { private AWSCredentialsConfig config; private FileSessionCredentialsProvider provider; public LazyFileSessionCredentialsProvider(AWSCredentialsConfig config) { this.config = config; } private FileSessionCredentialsProvider getUnderlyingProvider() { if (provider == null) { synchronized (config) { if (provider == null) { provider = new FileSessionCredentialsProvider(config.getFileSessionCredentials()); } } } return provider; } @Override public com.amazonaws.auth.AWSCredentials getCredentials() { return getUnderlyingProvider().getCredentials(); } @Override public void refresh() { getUnderlyingProvider().refresh(); } }