1 /*
2 * $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/taglibs/beanshell/src/java/org/apache/commons/jelly/tags/beanshell/BeanShellExpressionFactory.java,v 1.1 2002/05/21 07:58:55 jstrachan Exp $
3 * $Revision: 1.1 $
4 * $Date: 2002/05/21 07:58:55 $
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: BeanShellExpressionFactory.java,v 1.1 2002/05/21 07:58:55 jstrachan Exp $
61 */
62
63 package org.apache.commons.jelly.tags.define;
64
65 import java.lang.reflect.Method;
66 import java.util.HashMap;
67 import java.util.Map;
68
69 import org.apache.commons.jelly.JellyException;
70 import org.apache.commons.jelly.MissingAttributeException;
71 import org.apache.commons.jelly.Tag;
72 import org.apache.commons.jelly.XMLOutput;
73 import org.apache.commons.jelly.impl.Attribute;
74 import org.apache.commons.jelly.impl.DynamicBeanTag;
75 import org.apache.commons.jelly.impl.TagFactory;
76
77 import org.apache.commons.logging.Log;
78 import org.apache.commons.logging.LogFactory;
79
80
81 /***
82 * Binds a Java bean to the given named Jelly tag so that the attributes of
83 * the tag set the bean properties..
84 *
85 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
86 * @version $Revision: 1.1 $
87 */
88 public class BeanTag extends DefineTagSupport {
89
90 /*** The Log to which logging calls will be made. */
91 private static final Log log = LogFactory.getLog(BeanTag.class);
92
93 /*** An empty Map as I think Collections.EMPTY_MAP is only JDK 1.3 onwards */
94 private static final Map EMPTY_MAP = new HashMap();
95
96 /*** the name of the tag to create */
97 private String name;
98
99 /*** the Java class name to use for the tag */
100 private String className;
101
102 /*** the ClassLoader used to load beans */
103 private ClassLoader classLoader;
104
105 /*** the name of the attribute used for the variable name */
106 private String varAttribute = "var";
107
108 /*** the attribute definitions for this dynamic tag */
109 private Map attributes;
110
111 /***
112 * Adds a new attribute definition to this dynamic tag
113 */
114 public void addAttribute(Attribute attribute) {
115 if ( attributes == null ) {
116 attributes = new HashMap();
117 }
118 attributes.put( attribute.getName(), attribute );
119 }
120
121 // Tag interface
122 //-------------------------------------------------------------------------
123 public void doTag(XMLOutput output) throws Exception {
124 invokeBody(output);
125
126 if (name == null) {
127 throw new MissingAttributeException("name");
128 }
129 if (className == null) {
130 throw new MissingAttributeException("className");
131 }
132
133 Class theClass = null;
134 try {
135 ClassLoader classLoader = getClassLoader();
136 theClass = classLoader.loadClass(className);
137 }
138 catch (ClassNotFoundException e) {
139 try {
140 theClass = getClass().getClassLoader().loadClass(className);
141 }
142 catch (ClassNotFoundException e2) {
143 try {
144 theClass = Class.forName(className);
145 }
146 catch (ClassNotFoundException e3) {
147 log.error( "Could not load class: " + className + " exception: " + e, e );
148 throw new JellyException(
149 "Could not find class: "
150 + className
151 + " using ClassLoader: "
152 + classLoader);
153 }
154 }
155 }
156
157 final Class beanClass = theClass;
158 final Method invokeMethod = getInvokeMethod( theClass );
159 final Map beanAttributes = (attributes != null) ? attributes : EMPTY_MAP;
160
161 TagFactory factory = new TagFactory() {
162 public Tag createTag() {
163 return new DynamicBeanTag(beanClass, beanAttributes, varAttribute, invokeMethod);
164 }
165 };
166 getTagLibrary().registerBeanTag(name, factory);
167
168 // now lets clear the attributes for next invocation and help the GC
169 attributes = null;
170 }
171
172
173 // Properties
174 //-------------------------------------------------------------------------
175
176 /***
177 * Sets the name of the tag to create
178 */
179 public void setName(String name) {
180 this.name = name;
181 }
182
183 /***
184 * Sets the Java class name to use for the tag
185 */
186 public void setClassName(String className) {
187 this.className = className;
188 }
189
190 /***
191 * Sets the ClassLoader to use to load the class.
192 * If no value is set then the current threads context class
193 * loader is used.
194 */
195 public void setClassLoader(ClassLoader classLoader) {
196 this.classLoader = classLoader;
197 }
198
199 /***
200 * @return the ClassLoader to use to load classes
201 * or will use the thread context loader if none is specified.
202 */
203 public ClassLoader getClassLoader() {
204 if ( classLoader == null ) {
205 ClassLoader answer = Thread.currentThread().getContextClassLoader();
206 if ( answer == null ) {
207 answer = getClass().getClassLoader();
208 }
209 return answer;
210 }
211 return classLoader;
212 }
213
214 /***
215 * Sets the name of the attribute used to define the bean variable that this dynamic
216 * tag will output its results as. This defaults to 'var' though this property
217 * can be used to change this if it conflicts with a bean property called 'var'.
218 */
219 public void setVarAttribute(String varAttribute) {
220 this.varAttribute = varAttribute;
221 }
222
223
224 // Implementation methods
225 //-------------------------------------------------------------------------
226
227 /***
228 * Extracts the invoke method for the class if one is used.
229 */
230 protected Method getInvokeMethod( Class theClass ) throws Exception {
231 return null;
232 }
233 }
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