1 /*
2 * $Id: ELBaseTag.java 471754 2006-11-06 14:55:09Z husted $
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21 package org.apache.strutsel.taglib.html;
22
23 import org.apache.struts.taglib.html.BaseTag;
24 import org.apache.strutsel.taglib.utils.EvalHelper;
25
26 import javax.servlet.jsp.JspException;
27
28 /**
29 * Renders an HTML <base> element with an href attribute pointing to the
30 * absolute location of the enclosing JSP page. This tag is only valid when
31 * nested inside a head tag body. The presence of this tag allows the browser
32 * to resolve relative URL's to images, CSS stylesheets and other resources
33 * in a manner independent of the URL used to call the ActionServlet. <p> This
34 * class is a subclass of the class <code>org.apache.struts.taglib.html.BaseTag</code>
35 * which provides most of the described functionality. This subclass allows
36 * all attribute values to be specified as expressions utilizing the
37 * JavaServer Pages Standard Library expression language.
38 *
39 * @version $Rev: 471754 $
40 */
41 public class ELBaseTag extends BaseTag {
42 /**
43 * Instance variable mapped to "target" tag attribute. (Mapping set in
44 * associated BeanInfo class.)
45 */
46 private String targetExpr;
47
48 /**
49 * Instance variable mapped to "server" tag attribute. (Mapping set in
50 * associated BeanInfo class.)
51 */
52 private String serverExpr;
53
54 /**
55 * Instance variable mapped to "ref" tag attribute. (Mapping set in
56 * associated BeanInfo class.)
57 */
58 private String refExpr;
59
60 /**
61 * Getter method for "target" tag attribute. (Mapping set in associated
62 * BeanInfo class.)
63 */
64 public String getTargetExpr() {
65 return (targetExpr);
66 }
67
68 /**
69 * Getter method for "server" tag attribute. (Mapping set in associated
70 * BeanInfo class.)
71 */
72 public String getServerExpr() {
73 return (serverExpr);
74 }
75
76 /**
77 * Getter method for "ref" tag attribute. (Mapping set in associated
78 * BeanInfo class.)
79 */
80 public String getRefExpr() {
81 return (refExpr);
82 }
83
84 /**
85 * Setter method for "target" tag attribute. (Mapping set in associated
86 * BeanInfo class.)
87 */
88 public void setTargetExpr(String targetExpr) {
89 this.targetExpr = targetExpr;
90 }
91
92 /**
93 * Setter method for "server" tag attribute. (Mapping set in associated
94 * BeanInfo class.)
95 */
96 public void setServerExpr(String serverExpr) {
97 this.serverExpr = serverExpr;
98 }
99
100 /**
101 * Setter method for "ref" tag attribute. (Mapping set in associated
102 * BeanInfo class.)
103 */
104 public void setRefExpr(String refExpr) {
105 this.refExpr = refExpr;
106 }
107
108 /**
109 * Resets attribute values for tag reuse.
110 */
111 public void release() {
112 super.release();
113 setTargetExpr(null);
114 setServerExpr(null);
115 setRefExpr(null);
116 }
117
118 /**
119 * Process the start tag.
120 *
121 * @throws JspException if a JSP exception has occurred
122 */
123 public int doStartTag() throws JspException {
124 evaluateExpressions();
125
126 return (super.doStartTag());
127 }
128
129 /**
130 * Processes all attribute values which use the JSTL expression evaluation
131 * engine to determine their values.
132 *
133 * @throws JspException if a JSP exception has occurred
134 */
135 private void evaluateExpressions()
136 throws JspException {
137 String string = null;
138
139 if ((string =
140 EvalHelper.evalString("target", getTargetExpr(), this,
141 pageContext)) != null) {
142 setTarget(string);
143 }
144
145 if ((string =
146 EvalHelper.evalString("server", getServerExpr(), this,
147 pageContext)) != null) {
148 setServer(string);
149 }
150
151 if ((string =
152 EvalHelper.evalString("ref", getRefExpr(), this, pageContext)) != null) {
153 setRef(string);
154 }
155 }
156 }