1 package org.apache.turbine.modules;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache Turbine" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache Turbine", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 // Java Core Classes
58 import java.util.Vector;
59
60 // Turbine Utility Classes
61 import org.apache.turbine.TurbineConstants;
62 import org.apache.turbine.services.resources.TurbineResources;
63 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService;
64 import org.apache.turbine.services.TurbineServices;
65 import org.apache.turbine.util.ObjectUtils;
66 import org.apache.turbine.util.RunData;
67
68
69 /***
70 * The purpose of this class is to allow one to load and execute
71 * Layout modules.
72 *
73 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
74 * @version $Id: LayoutLoader.java,v 1.1.1.1 2001/08/16 05:08:30 jvanzyl Exp $
75 */
76 public class LayoutLoader extends GenericLoader
77 {
78 /*** The single instance of this class. */
79 private static LayoutLoader instance = new LayoutLoader(
80 TurbineResources.getInt(TurbineConstants.LAYOUT_CACHE_SIZE, 10));
81
82 /***
83 * These ctor's are private to force clients to use getInstance()
84 * to access this class.
85 */
86 private LayoutLoader()
87 {
88 super();
89 }
90
91 /***
92 * These ctor's are private to force clients to use getInstance()
93 * to access this class.
94 */
95 private LayoutLoader(int i)
96 {
97 super(i);
98 }
99
100 /***
101 * Adds an instance of an object into the hashtable.
102 *
103 * @param name Name of object.
104 * @param layout Layout to be associated with name.
105 */
106 private void addInstance( String name, Layout layout )
107 {
108 if ( cache() )
109 this.put( name, (Layout) layout );
110 }
111
112 /***
113 * Attempts to load and execute the external layout.
114 *
115 * @param data Turbine information.
116 * @param name Name of object that will execute the layout.
117 * @exception Exception a generic exception.
118 */
119 public void exec( RunData data, String name )
120 throws Exception
121 {
122 // Execute layout
123 getInstance(name).build(data);
124 }
125
126 /***
127 * Pulls out an instance of the object by name. Name is just the
128 * single name of the object.
129 *
130 * @param name Name of object instance.
131 * @return A Layout with the specified name, or null.
132 * @exception Exception a generic exception.
133 */
134 public Layout getInstance(String name)
135 throws Exception
136 {
137 Layout layout = null;
138
139 if ( cache() && this.containsKey( name ) )
140 {
141 layout = (Layout) this.get ( name );
142 }
143 else
144 {
145 // We get the broker service
146 AssemblerBrokerService ab =
147 (AssemblerBrokerService)TurbineServices.getInstance()
148 .getService (AssemblerBrokerService.SERVICE_NAME);
149
150 try
151 {
152 // Attempt to load the screen
153 layout = (Layout) ab.getAssembler(
154 AssemblerBrokerService.LAYOUT_TYPE,name);
155 }
156 catch (ClassCastException cce)
157 {
158 // This can alternatively let this exception be thrown
159 // So that the ClassCastException is shown in the
160 // browser window. Like this it shows "Screen not Found"
161 layout = null;
162 }
163
164 if (layout == null)
165 {
166 // If we did not find a screen we should try and give
167 // the user a reason for that...
168 // FIX ME: The AssemblerFactories should each add it's own
169 // string here...
170 Vector packages = TurbineResources.getVector(
171 TurbineConstants.MODULE_PACKAGES);
172 ObjectUtils.addOnce( packages,
173 GenericLoader.getBasePackage() );
174
175 throw new ClassNotFoundException(
176 "\n\n\tRequested Layout not found: " + name + "\n" +
177 "\tTurbine looked in the following modules.packages " +
178 "path: \n\t" + packages.toString() + "\n");
179 }
180 else if ( cache() )
181 {
182 // The new instance is added to the cache
183 addInstance( name, layout );
184 }
185 }
186 return layout;
187 }
188
189 /***
190 * The method through which this class is accessed.
191 *
192 * @return The single instance of this class.
193 */
194 public static LayoutLoader getInstance()
195 {
196 return instance;
197 }
198 }
This page was automatically generated by Maven