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.io.File;
66 import java.net.URL;
67 import java.net.URLClassLoader;
68
69 import org.apache.commons.jelly.MissingAttributeException;
70 import org.apache.commons.jelly.XMLOutput;
71 import org.apache.commons.logging.Log;
72 import org.apache.commons.logging.LogFactory;
73
74
75 /***
76 * Creates a new <code>URLClassLoader</code> to dynamically
77 * load tags froms.
78 *
79 * @author <a href="mailto:stephenh@chase3000.com">Stephen Haberman</a>
80 * @version $Revision: 1.1 $
81 */
82 public class ClassLoaderTag extends BeanTag {
83
84 /*** The Log to which logging calls will be made. */
85 private static final Log log = LogFactory.getLog(ClassLoaderTag.class);
86
87 /*** The name to export the classloader to. */
88 private String var;
89
90 /*** The URL to load the classes from. */
91 private String url;
92
93 // Properties
94 //-------------------------------------------------------------------------
95
96 /***
97 * @return the variable to store the class loader in
98 */
99 public String getVar() {
100 return this.var;
101 }
102
103 /***
104 * @param var the variable to store the class loader in
105 */
106 public void setVar(String var) {
107 this.var = var;
108 }
109
110 /***
111 * @return the url to load the classes from
112 */
113 public String getUrl() {
114 return this.url;
115 }
116
117 /***
118 * @param url the url to load the classes from
119 */
120 public void setUrl(String url) {
121 this.url = url;
122 }
123
124 // Implementation methods
125 //-------------------------------------------------------------------------
126
127 public void doTag(XMLOutput output) throws Exception {
128 if ( getVar() == null ) {
129 throw new MissingAttributeException( "var" );
130 }
131 if ( getUrl() == null ) {
132 throw new MissingAttributeException( "url" );
133 }
134
135 ClassLoader parent = Thread.currentThread().getContextClassLoader();
136 if (parent == null) {
137 parent = getClass().getClassLoader();
138 }
139
140 URLClassLoader newClassLoader = new URLClassLoader(
141 new URL[] { new URL(getUrl()) },
142 parent );
143
144 log.debug("Storing the new classloader in " + getVar());
145
146 context.setVariable(getVar(), newClassLoader);
147 }
148
149 }
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