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. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.http.protocol; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import org.apache.http.annotation.ThreadSafe; import org.apache.http.util.Args; /** * Default implementation of {@link HttpContext}. * <p> * Please note instances of this class can be thread unsafe if the * parent context is not thread safe. * * @since 4.0 */ @ThreadSafe public class BasicHttpContextHC4 implements HttpContext { private final HttpContext parentContext; private final Map<String, Object> map; public BasicHttpContextHC4() { this(null); } public BasicHttpContextHC4(final HttpContext parentContext) { super(); this.map = new ConcurrentHashMap<String, Object>(); this.parentContext = parentContext; } public Object getAttribute(final String id) { Args.notNull(id, "Id"); Object obj = this.map.get(id); if (obj == null && this.parentContext != null) { obj = this.parentContext.getAttribute(id); } return obj; } public void setAttribute(final String id, final Object obj) { Args.notNull(id, "Id"); if (obj != null) { this.map.put(id, obj); } else { this.map.remove(id); } } public Object removeAttribute(final String id) { Args.notNull(id, "Id"); return this.map.remove(id); } /** * @since 4.2 */ public void clear() { this.map.clear(); } @Override public String toString() { return this.map.toString(); } }