001 /**
002 * Java Gui Builder - A library to build GUIs using an XML file.
003 * Copyright 2002, 2003 (C) François Beausoleil
004 *
005 * This library is free software; you can redistribute it and/or
006 * modify it under the terms of the GNU Lesser General Public
007 * License as published by the Free Software Foundation; either
008 * version 2.1 of the License, or (at your option) any later version.
009 *
010 * This library is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
013 * Lesser General Public License for more details.
014 *
015 * You should have received a copy of the GNU Lesser General Public
016 * License along with this library; if not, write to the Free Software
017 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
018 */
019
020 package jgb.factories.swing;
021
022 import jgb.builder.TagHandler;
023 import jgb.builder.TagHandlerFactory;
024
025 import java.util.HashMap;
026 import java.util.Map;
027
028 /**
029 * Implementation of {@link jgb.builder.TagHandlerFactory TagHandlerFactory}
030 * that returns {@link jgb.builder.TagHandler TagHandler}s based on
031 * a package name and class suffix.
032 * This factory will use the following formula to build the fully-qualified
033 * name of the class to instantiate:
034 * <ol>
035 * <li>The package name (prefix)</li>
036 * <li>a period (dot - ".")</li>
037 * <li>the first letter of the tag name, upper cased</li>
038 * <li>the remaining characters of the tag name</li>
039 * <li>the suffix</li>
040 * </ol>
041 * For example, if an instance of this factory was created with the package name
042 * equal to "com.xyz.handlers" and the suffix equal to "XmlTagHandler",
043 * {@link #getHandlerFor(java.lang.String) getHandlerFor(String)} would return
044 * an instance of <em>com.xyz.handlers.WindowsXmlTagHandler</em> if the tag name was
045 * equal to <em>windows</em>.<br />
046 * This factory expects all {@link jgb.builder.TagHandler TagHandler}s
047 * to have a no-arg constructor.
048 *
049 * @since 0.1.1a
050 * @author Francois Beausoleil, <a href="mailto:fbos@users.sourceforge.net">fbos@users.sourceforge.net</a>
051 */
052 public class PackageTagHandlerFactory implements TagHandlerFactory {
053 private String basePackageName;
054 private String classSuffix;
055 private Map tagsMap = new HashMap();
056
057 /**
058 * @param basePackageName A String that will be prepended to the final
059 * class name before instantiation.
060 * @param classSuffix A String that will be appended to the final class name
061 * before instantiation.
062 */
063 public PackageTagHandlerFactory(final String basePackageName, final String classSuffix) {
064 if (basePackageName.endsWith(".")) {
065 this.basePackageName = basePackageName;
066 } else {
067 this.basePackageName = basePackageName + ".";
068 }
069
070 this.classSuffix = classSuffix;
071 }
072
073 public TagHandler getHandlerFor(final String tagName) throws ClassNotFoundException {
074 if (false == tagsMap.containsKey(tagName)) {
075 tagsMap.put(tagName, createTag(tagName));
076 }
077
078 return (TagHandler)tagsMap.get(tagName);
079 }
080
081 private TagHandler createTag(final String tagName) throws ClassNotFoundException {
082 String className = buildClassName(tagName);
083 Class tagClass = Class.forName(className);
084 try {
085 return (TagHandler)tagClass.newInstance();
086 } catch (Exception e) {
087 throw new ClassNotFoundException("Could not instantiate " + tagName, e);
088 }
089 }
090
091 private String buildClassName(final String tagName) {
092 StringBuffer classNameBuffer = new StringBuffer();
093 classNameBuffer.append(basePackageName);
094 classNameBuffer.append(Character.toUpperCase(tagName.charAt(0)));
095 classNameBuffer.append(tagName.substring(1));
096 classNameBuffer.append(classSuffix);
097 return classNameBuffer.toString();
098 }
099 }