Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 com.twitter.distributedlog.config; import com.google.common.base.Preconditions; import org.apache.commons.configuration.AbstractConfiguration; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.Iterator; import java.util.concurrent.ConcurrentHashMap; /** * Configuration view built on concurrent hash map for fast thread-safe access. * Notes: * 1. Multi-property list aggregation will not work in this class. I.e. commons config * normally combines all properties with the same key into one list property automatically. * This class simply overwrites any existing mapping. */ public class ConcurrentBaseConfiguration extends AbstractConfiguration { static final Logger LOG = LoggerFactory.getLogger(ConcurrentBaseConfiguration.class); private final ConcurrentHashMap<String, Object> map; public ConcurrentBaseConfiguration() { this.map = new ConcurrentHashMap<String, Object>(); } @Override protected void addPropertyDirect(String key, Object value) { Preconditions.checkNotNull(value); map.put(key, value); } @Override public Object getProperty(String key) { return map.get(key); } @Override public Iterator getKeys() { return map.keySet().iterator(); } @Override public boolean containsKey(String key) { return map.containsKey(key); } @Override public boolean isEmpty() { return map.isEmpty(); } @Override protected void clearPropertyDirect(String key) { map.remove(key); } }