001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * Portions Copyright Apache Software Foundation.
007: *
008: * The contents of this file are subject to the terms of either the GNU
009: * General Public License Version 2 only ("GPL") or the Common Development
010: * and Distribution License("CDDL") (collectively, the "License"). You
011: * may not use this file except in compliance with the License. You can obtain
012: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
013: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
014: * language governing permissions and limitations under the License.
015: *
016: * When distributing the software, include this License Header Notice in each
017: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
018: * Sun designates this particular file as subject to the "Classpath" exception
019: * as provided by Sun in the GPL Version 2 section of the License file that
020: * accompanied this code. If applicable, add the following below the License
021: * Header, with the fields enclosed by brackets [] replaced by your own
022: * identifying information: "Portions Copyrighted [year]
023: * [name of copyright owner]"
024: *
025: * Contributor(s):
026: *
027: * If you wish your version of this file to be governed by only the CDDL or
028: * only the GPL Version 2, indicate your decision by adding "[Contributor]
029: * elects to include this software in this distribution under the [CDDL or GPL
030: * Version 2] license." If you don't indicate a single choice of license, a
031: * recipient has the option to distribute your version of this file under
032: * either the CDDL, the GPL Version 2 or to extend the choice of license to
033: * its licensees as provided above. However, if you add GPL Version 2 code
034: * and therefore, elected the GPL Version 2 license, then the option applies
035: * only if the new code is made subject to such option by the copyright
036: * holder.
037: */
038:
039: package org.apache.taglibs.standard.tag.el.xml;
040:
041: import javax.servlet.jsp.JspException;
042:
043: import org.apache.taglibs.standard.tag.common.xml.ParamSupport;
044: import org.apache.taglibs.standard.tag.el.core.ExpressionUtil;
045:
046: /**
047: * <p>A handler for <param> that accepts attributes as Strings
048: * and evaluates them as expressions at runtime.</p>
049: *
050: * @author Shawn Bayern
051: */
052:
053: public class ParamTag extends ParamSupport {
054:
055: //*********************************************************************
056: // 'Private' state (implementation details)
057:
058: private String name_; // stores EL-based property
059: private String value_; // stores EL-based property
060:
061: //*********************************************************************
062: // Constructor
063:
064: public ParamTag() {
065: super ();
066: init();
067: }
068:
069: //*********************************************************************
070: // Tag logic
071:
072: // evaluates expression and chains to parent
073: public int doStartTag() throws JspException {
074:
075: // evaluate any expressions we were passed, once per invocation
076: evaluateExpressions();
077:
078: // chain to the parent implementation
079: return super .doStartTag();
080: }
081:
082: // Releases any resources we may have (or inherit)
083: public void release() {
084: super .release();
085: init();
086: }
087:
088: //*********************************************************************
089: // Accessor methods
090:
091: // for EL-based attribute
092: public void setName(String name_) {
093: this .name_ = name_;
094: }
095:
096: public void setValue(String value_) {
097: this .value_ = value_;
098: }
099:
100: //*********************************************************************
101: // Private (utility) methods
102:
103: // (re)initializes state (during release() or construction)
104: private void init() {
105: // null implies "no expression"
106: name_ = value_ = null;
107: }
108:
109: /* Evaluates expressions as necessary */
110: private void evaluateExpressions() throws JspException {
111: /*
112: * Note: we don't check for type mismatches here; we assume
113: * the expression evaluator will return the expected type
114: * (by virtue of knowledge we give it about what that type is).
115: * A ClassCastException here is truly unexpected, so we let it
116: * propagate up.
117: */
118:
119: name = (String) ExpressionUtil.evalNotNull("param", "name",
120: name_, String.class, this , pageContext);
121: value = ExpressionUtil.evalNotNull("param", "value", value_,
122: Object.class, this, pageContext);
123: }
124: }
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