Java tutorial
/* * Copyright 2003-2004 The Apache Software Foundation * * 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.apache.commons.chain; import java.util.Map; /** * <p>A {@link Context} represents the state information that is * accessed and manipulated by the execution of a {@link Command} or a * {@link Chain}. Specialized implementations of {@link Context} will * typically add JavaBeans properties that contain typesafe accessors * to information that is relevant to a particular use case for this * context, and/or add operations that affect the state information * that is saved in the context.</p> * * <p>Implementations of {@link Context} must also implement all of the * required and optional contracts of the <code>java.util.Map</code> * interface.</p> * * <p>It is strongly recommended, but not required, that JavaBeans * properties added to a particular {@link Context} implementation exhibit * <em>Attribute-Property Transparency</em>. In other words, * a value stored via a call to <code>setFoo(value)</code> should be visible * by calling <code>get("foo")</code>, and a value stored * via a call to <code>put("foo", value)</code> should be * visible by calling <code>getFoo()</code>. If your {@link Context} * implementation class exhibits this featue, it becomes easier to reuse the * implementation in multiple environments, without the need to cast to a * particular implementation class in order to access the property getter * and setter methods.</p> * * <p>To protect applications from evolution of this interface, specialized * implementations of {@link Context} should generally be created by extending * the provided base class ({@link org.apache.commons.chain.impl.ContextBase}) * rather than directly implementing this interface.</p> * * <p>Applications should <strong>NOT</strong> assume that * {@link Context} implementations, or the values stored in its * attributes, may be accessed from multiple threads * simultaneously unless this is explicitly documented for a particular * implementation.</p> * * @author Craig R. McClanahan * @version $Revision: 1.6 $ $Date: 2004/02/25 00:01:07 $ */ public interface Context extends Map { }