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.lang.reflect.InvocationTargetException;
65 import java.lang.reflect.Method;
66 import java.util.HashSet;
67 import java.util.Iterator;
68 import java.util.Map;
69 import java.util.Set;
70
71 import org.apache.commons.beanutils.ConvertingWrapDynaBean;
72
73 import org.apache.commons.collections.BeanMap;
74
75 import org.apache.commons.jelly.DynaBeanTagSupport;
76 import org.apache.commons.jelly.JellyException;
77 import org.apache.commons.jelly.MissingAttributeException;
78 import org.apache.commons.jelly.Tag;
79 import org.apache.commons.jelly.XMLOutput;
80 import org.apache.commons.jelly.expression.Expression;
81 import org.apache.commons.jelly.impl.BeanSource;
82
83 import org.apache.commons.logging.Log;
84 import org.apache.commons.logging.LogFactory;
85
86 /***
87 * This tag is bound onto a Java Bean class. When the tag is invoked a bean will be created
88 * using the tags attributes.
89 * The bean may also have an invoke method called invoke(), run(), execute() or some such method
90 * which will be invoked after the bean has been configured.</p>
91 *
92 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
93 * @author <a href="mailto:jason@zenplex.com">Jason van Zyl</a>
94 * @version $Revision: 1.7 $
95 */
96 public class DynamicBeanTag extends DynaBeanTagSupport implements BeanSource {
97
98 /*** The Log to which logging calls will be made. */
99 private static final Log log = LogFactory.getLog(DynamicBeanTag.class);
100
101 /*** Empty arguments for Method.invoke() */
102 private static final Object[] emptyArgs = {};
103
104 /*** the bean class */
105 private Class beanClass;
106
107 /*** the current bean instance */
108 private Object bean;
109
110 /*** the method to invoke on the bean */
111 private Method method;
112
113 /***
114 * the tag attribute name that is used to declare the name
115 * of the variable to export after running this tag
116 */
117 private String variableNameAttribute;
118
119 /*** the current variable name that the bean should be exported as */
120 private String var;
121
122 /*** the set of attribute names we've already set */
123 private Set setAttributesSet = new HashSet();
124
125 /*** the attribute definitions */
126 private Map attributes;
127
128 public DynamicBeanTag(Class beanClass, Map attributes, String variableNameAttribute, Method method) {
129 this.beanClass = beanClass;
130 this.method = method;
131 this.attributes = attributes;
132 this.variableNameAttribute = variableNameAttribute;
133 }
134
135 public void beforeSetAttributes() throws Exception {
136 // create a new dynabean before the attributes are set
137 bean = beanClass.newInstance();
138 setDynaBean( new ConvertingWrapDynaBean( bean ) );
139
140 setAttributesSet.clear();
141 }
142
143 public void setAttribute(String name, Object value) throws Exception {
144 boolean isVariableName = false;
145 if (variableNameAttribute != null ) {
146 if ( variableNameAttribute.equals( name ) ) {
147 if (value == null) {
148 var = null;
149 }
150 else {
151 var = value.toString();
152 }
153 isVariableName = true;
154 }
155 }
156 if (! isVariableName) {
157
158 // #### strictly speaking we could
159 // know what attributes are specified at compile time
160 // so this dynamic set is unnecessary
161 setAttributesSet.add(name);
162
163 // we could maybe implement attribute specific validation here
164
165 super.setAttribute(name, value);
166 }
167 }
168
169 // Tag interface
170 //-------------------------------------------------------------------------
171 public void doTag(XMLOutput output) throws Exception {
172
173 // lets find any attributes that are not set and
174 for ( Iterator iter = attributes.values().iterator(); iter.hasNext(); ) {
175 Attribute attribute = (Attribute) iter.next();
176 String name = attribute.getName();
177 if ( ! setAttributesSet.contains( name ) ) {
178 if ( attribute.isRequired() ) {
179 throw new MissingAttributeException(name);
180 }
181 // lets get the default value
182 Object value = null;
183 Expression expression = attribute.getDefaultValue();
184 if ( expression != null ) {
185 value = expression.evaluate(context);
186 }
187
188 // only set non-null values?
189 if ( value != null ) {
190 super.setAttribute(name, value);
191 }
192 }
193 }
194
195 // If the dynamic bean is itself a tag, let it execute itself
196 if (bean instanceof Tag)
197 {
198 Tag tag = (Tag) bean;
199 tag.setBody(getBody());
200 tag.setContext(getContext());
201 tag.setParent(getParent());
202 ((Tag) bean).doTag(output);
203
204 return;
205 }
206
207 invokeBody(output);
208
209 // export the bean if required
210 if ( var != null ) {
211 context.setVariable(var, bean);
212 }
213
214 // now, I may invoke the 'execute' method if I have one
215 if ( method != null ) {
216 try {
217 method.invoke( bean, emptyArgs );
218 }
219 catch (IllegalAccessException e) {
220 methodInvocationError(bean, method, e);
221 }
222 catch (IllegalArgumentException e) {
223 methodInvocationError(bean, method, e);
224 }
225 catch (InvocationTargetException e) {
226 // methodInvocationError(bean, method, e);
227
228 Throwable inner = e.getTargetException();
229
230 if ( inner instanceof Exception )
231 {
232 throw (Exception) inner;
233 }
234 else
235 {
236 throw new JellyException( inner );
237 }
238 }
239 }
240 }
241
242 /***
243 * Report the state of the bean when method invocation fails
244 * so that the user can determine any problems that might
245 * be occuring while using dynamic jelly beans.
246 *
247 * @param bean Bean on which <code>method</code was invoked
248 * @param method Method that was invoked
249 * @param e Exception throw when <code>method</code> was invoked
250 */
251 private void methodInvocationError(Object bean, Method method, Exception e) throws Exception {
252 log.error("Could not invoke " + method, e);
253 BeanMap beanMap = new BeanMap(bean);
254
255 log.error("Bean properties:");
256 for (Iterator i = beanMap.keySet().iterator(); i.hasNext();) {
257 String property = (String) i.next();
258 Object value = beanMap.get(property);
259 log.error(property + " -> " + value);
260 }
261
262 log.error(beanMap);
263 throw e;
264 }
265
266 // Properties
267 //-------------------------------------------------------------------------
268 /***
269 * @return the bean that has just been created
270 */
271 public Object getBean() {
272 return bean;
273 }
274 }
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