ELForwardTag


1   /*
2    * $Id: ELForwardTag.java 54933 2004-10-16 17:04:52Z germuska $ 
3    *
4    * Copyright 1999-2004 The Apache Software Foundation.
5    * 
6    * Licensed under the Apache License, Version 2.0 (the "License");
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    * 
10   *      http://www.apache.org/licenses/LICENSE-2.0
11   * 
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.strutsel.taglib.logic;
20  
21  import org.apache.struts.taglib.logic.ForwardTag;
22  import javax.servlet.jsp.JspException  ;
23  import org.apache.strutsel.taglib.utils.EvalHelper;
24  
25  /**
26   * Perform a forward or redirect to a page that is looked up in the
27   * configuration information associated with our application.
28   *<p>
29   * This class is a subclass of the class
30   * <code>org.apache.struts.taglib.logix.ForwardTag</code> which provides most of
31   * the described functionality.  This subclass allows all attribute values to
32   * be specified as expressions utilizing the JavaServer Pages Standard Library
33   * expression language.
34   *
35   * @version $Rev: 54933 $
36   */
37  public class ELForwardTag extends ForwardTag {
38  
39      /**
40       * Instance variable mapped to "name" tag attribute.
41       * (Mapping set in associated BeanInfo class.)
42       */
43      private String   nameExpr;
44  
45      /**
46       * Getter method for "name" tag attribute.
47       * (Mapping set in associated BeanInfo class.)
48       */
49      public String   getNameExpr() { return (nameExpr); }
50  
51      /**
52       * Setter method for "name" tag attribute.
53       * (Mapping set in associated BeanInfo class.)
54       */
55      public void setNameExpr(String   nameExpr) { this.nameExpr = nameExpr; }
56  
57      /**
58       * Resets attribute values for tag reuse.
59       */
60      public void release()
61      {
62          super.release();
63          setNameExpr(null);
64      }
65      
66      /**
67       * Process the start tag.
68       *
69       * @exception JspException if a JSP exception has occurred
70       */
71      public int doStartTag() throws JspException   {
72          evaluateExpressions();
73          return(super.doStartTag());
74      }
75  
76      /**
77       * Processes all attribute values which use the JSTL expression evaluation
78       * engine to determine their values.
79       *
80       * @exception JspException if a JSP exception has occurred
81       */
82      private void evaluateExpressions() throws JspException   {
83          String    string  = null;
84  
85          if ((string = EvalHelper.evalString("name", getNameExpr(),
86                                              this, pageContext)) != null)
87              setName(string);
88      }
89  }
90
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