1 /*
2 * $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/define/DynamicTag.java,v 1.7 2002/05/17 15:18:12 jstrachan Exp $
3 * $Revision: 1.7 $
4 * $Date: 2002/05/17 15:18:12 $
5 *
6 * ====================================================================
7 *
8 * The Apache Software License, Version 1.1
9 *
10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
11 * reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 *
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
23 * distribution.
24 *
25 * 3. The end-user documentation included with the redistribution, if
26 * any, must include the following acknowlegement:
27 * "This product includes software developed by the
28 * Apache Software Foundation (http://www.apache.org/)."
29 * Alternately, this acknowlegement may appear in the software itself,
30 * if and wherever such third-party acknowlegements normally appear.
31 *
32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33 * Foundation" must not be used to endorse or promote products derived
34 * from this software without prior written permission. For written
35 * permission, please contact apache@apache.org.
36 *
37 * 5. Products derived from this software may not be called "Apache"
38 * nor may "Apache" appear in their names without prior written
39 * permission of the Apache Group.
40 *
41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This software consists of voluntary contributions made by many
56 * individuals on behalf of the Apache Software Foundation. For more
57 * information on the Apache Software Foundation, please see
58 * <http://www.apache.org/>.
59 *
60 * $Id: DynamicTag.java,v 1.7 2002/05/17 15:18:12 jstrachan Exp $
61 */
62 package org.apache.commons.jelly.impl;
63
64 import java.util.HashSet;
65 import java.util.Iterator;
66 import java.util.Map;
67 import java.util.Set;
68
69 import org.apache.commons.beanutils.DynaBean;
70 import org.apache.commons.beanutils.DynaClass;
71
72 import org.apache.commons.jelly.DynaBeanTagSupport;
73 import org.apache.commons.jelly.JellyException;
74 import org.apache.commons.jelly.MissingAttributeException;
75 import org.apache.commons.jelly.Tag;
76 import org.apache.commons.jelly.XMLOutput;
77 import org.apache.commons.jelly.expression.Expression;
78 import org.apache.commons.jelly.impl.BeanSource;
79
80 import org.apache.commons.logging.Log;
81 import org.apache.commons.logging.LogFactory;
82
83 /***
84 * This tag is bound onto a {@link DynaClass} instance.
85 * When the tag is invoked a {@link DynaBean will be created using the tags attributes.
86 * So this class is like a {@link DynaBean} implemenation of {@link DynamicBeanTag}
87 *
88 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
89 * @version $Revision: 1.7 $
90 */
91 public class DynamicDynaBeanTag extends DynaBeanTagSupport implements BeanSource {
92
93 /*** The Log to which logging calls will be made. */
94 private static final Log log = LogFactory.getLog(DynamicDynaBeanTag.class);
95
96 /*** the bean class */
97 private DynaClass beanClass;
98
99 /***
100 * the tag attribute name that is used to declare the name
101 * of the variable to export after running this tag
102 */
103 private String variableNameAttribute;
104
105 /*** the current variable name that the bean should be exported as */
106 private String var;
107
108 /*** the set of attribute names we've already set */
109 private Set setAttributesSet = new HashSet();
110
111 /*** the attribute definitions */
112 private Map attributes;
113
114 public DynamicDynaBeanTag(DynaClass beanClass, Map attributes, String variableNameAttribute) {
115 this.beanClass = beanClass;
116 this.attributes = attributes;
117 this.variableNameAttribute = variableNameAttribute;
118 }
119
120 public void beforeSetAttributes() throws Exception {
121 // create a new dynabean before the attributes are set
122 setDynaBean( beanClass.newInstance() );
123
124 setAttributesSet.clear();
125 }
126
127 public void setAttribute(String name, Object value) throws Exception {
128 boolean isVariableName = false;
129 if (variableNameAttribute != null ) {
130 if ( variableNameAttribute.equals( name ) ) {
131 if (value == null) {
132 var = null;
133 }
134 else {
135 var = value.toString();
136 }
137 isVariableName = true;
138 }
139 }
140 if (! isVariableName) {
141
142 // #### strictly speaking we could
143 // know what attributes are specified at compile time
144 // so this dynamic set is unnecessary
145 setAttributesSet.add(name);
146
147 // we could maybe implement attribute specific validation here
148
149 super.setAttribute(name, value);
150 }
151 }
152
153 // Tag interface
154 //-------------------------------------------------------------------------
155 public void doTag(XMLOutput output) throws Exception {
156
157 // lets find any attributes that are not set and
158 for ( Iterator iter = attributes.values().iterator(); iter.hasNext(); ) {
159 Attribute attribute = (Attribute) iter.next();
160 String name = attribute.getName();
161 if ( ! setAttributesSet.contains( name ) ) {
162 if ( attribute.isRequired() ) {
163 throw new MissingAttributeException(name);
164 }
165 // lets get the default value
166 Object value = null;
167 Expression expression = attribute.getDefaultValue();
168 if ( expression != null ) {
169 value = expression.evaluate(context);
170 }
171
172 // only set non-null values?
173 if ( value != null ) {
174 super.setAttribute(name, value);
175 }
176 }
177 }
178
179 invokeBody(output);
180
181 // export the bean if required
182 if ( var != null ) {
183 context.setVariable(var, getDynaBean());
184 }
185 }
186
187 // Properties
188 //-------------------------------------------------------------------------
189 /***
190 * @return the bean that has just been created
191 */
192 public Object getBean() {
193 return getDynaBean();
194 }
195 }
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