001: /* ====================================================================
002: * The Jcorporate Apache Style Software License, Version 1.2 05-07-2002
003: *
004: * Copyright (c) 1995-2003 Jcorporate Ltd. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above copyright
011: * notice, this list of conditions and the following disclaimer.
012: *
013: * 2. Redistributions in binary form must reproduce the above copyright
014: * notice, this list of conditions and the following disclaimer in
015: * the documentation and/or other materials provided with the
016: * distribution.
017: *
018: * 3. The end-user documentation included with the redistribution,
019: * if any, must include the following acknowledgment:
020: * "This product includes software developed by Jcorporate Ltd.
021: * (http://www.jcorporate.com/)."
022: * Alternately, this acknowledgment may appear in the software itself,
023: * if and wherever such third-party acknowledgments normally appear.
024: *
025: * 4. "Jcorporate" and product names such as "Expresso" must
026: * not be used to endorse or promote products derived from this
027: * software without prior written permission. For written permission,
028: * please contact info@jcorporate.com.
029: *
030: * 5. Products derived from this software may not be called "Expresso",
031: * or other Jcorporate product names; nor may "Expresso" or other
032: * Jcorporate product names appear in their name, without prior
033: * written permission of Jcorporate Ltd.
034: *
035: * 6. No product derived from this software may compete in the same
036: * market space, i.e. framework, without prior written permission
037: * of Jcorporate Ltd. For written permission, please contact
038: * partners@jcorporate.com.
039: *
040: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
041: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
042: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
043: * DISCLAIMED. IN NO EVENT SHALL JCORPORATE LTD OR ITS CONTRIBUTORS
044: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
045: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
046: * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
047: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
048: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
049: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
050: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
051: * SUCH DAMAGE.
052: * ====================================================================
053: *
054: * This software consists of voluntary contributions made by many
055: * individuals on behalf of the Jcorporate Ltd. Contributions back
056: * to the project(s) are encouraged when you make modifications.
057: * Please send them to support@jcorporate.com. For more information
058: * on Jcorporate Ltd. and its products, please see
059: * <http://www.jcorporate.com/>.
060: *
061: * Portions of this software are based upon other open source
062: * products and are subject to their respective licenses.
063: */
064: package com.jcorporate.expresso.kernel;
065:
066: import EDU.oswego.cs.dl.util.concurrent.ReadWriteLock;
067: import EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock;
068: import org.apache.log4j.Logger;
069:
070: /**
071: * This class provides basic implementations of the Containable Interface to
072: * save the typical programmer lots of typing. Under 99% of the conditions it
073: * should be sufficient to derivce your container component from this class
074: * instead of implementing the interfaces in a raw fashion.
075: *
076: * @author Michael Rimov
077: * @since Expresso 5.1
078: */
079: abstract public class ContainerComponentBase extends ComponentBase
080: implements Containable {
081:
082: /**
083: * Read Write lock on the container
084: */
085: private ReadWriteLock containerLock = new WriterPreferenceReadWriteLock();
086:
087: /**
088: * The log4j Logger
089: */
090: private static Logger log = Logger
091: .getLogger(ContainerComponentBase.class);
092:
093: /**
094: * This is the 1:1 implementation class. (One exists for each containable component)
095: */
096: private ComponentContainer implementation;
097:
098: /**
099: * Default constructor that currently does nothing.
100: */
101: public ContainerComponentBase() {
102: super ();
103: }
104:
105: /**
106: * Sets the marker to the ComponentContainer (which has a 1:1 instance mapping
107: * with Containable). This is often called by the actual implementation
108: * of the ComponentContainer.
109: *
110: * @param newContainer a <code>ComponentCo
111: */
112: public synchronized void setContainerImplementation(
113: ComponentContainer newContainer) {
114: try {
115: containerLock.writeLock().acquire();
116: } catch (InterruptedException ex) {
117: log
118: .error(
119: "Interrupted while waiting for write lock. Aborting method",
120: ex);
121: }
122: implementation = newContainer;
123:
124: containerLock.writeLock().release();
125: }
126:
127: /**
128: * Retrieves the actual container implementation
129: *
130: * @return ComponentContainer
131: */
132: public synchronized ComponentContainer getContainerImplementation() {
133: try {
134: containerLock.readLock().acquire();
135: } catch (InterruptedException ex) {
136: log
137: .error(
138: "Interrupted while waiting for read lock. Aborting method",
139: ex);
140: }
141:
142: try {
143: return implementation;
144: } finally {
145: containerLock.readLock().release();
146: }
147: }
148:
149: /**
150: * <p>Convenience method for Container clients. Recommended
151: * Implementation:</p>
152: * <p/>
153: * <code>
154: * ExpressoComponent getComponent(String componentName) {<br />
155: * return this.getContainerImplementation().getComponent(componentName);
156: * }<br />
157: * <p/>
158: * </code>
159: * </p>
160: *
161: * @param componentName The name of the component to retrieve
162: * @return an ExpressoComponent or null if the specified name doesn't exist
163: */
164: public synchronized ExpressoComponent locateComponent(
165: String componentName) {
166: try {
167: containerLock.readLock().acquire();
168: } catch (InterruptedException ex) {
169: log
170: .error(
171: "Interrupted while waiting for read lock. Aborting method",
172: ex);
173: }
174:
175: try {
176: return implementation.locateComponent(componentName);
177: } finally {
178: containerLock.readLock().release();
179: }
180: }
181: }
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