AttributeTag


1   /*
2    * Copyright 1999,2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.taglibs.application;
18  
19  import java.util.*;
20  import javax.servlet.*;
21  import javax.servlet.http.*;
22  import javax.servlet.jsp.*;
23  import javax.servlet.jsp.tagext.*;
24  
25  /**
26   * JSP Tag <b>attribute</b>, used to output the value for a single
27   * ServletContext attribute named with <b>name</b>.
28   * <p>
29   * JSP Tag Lib Descriptor
30   * <p><pre>
31   * &lt;name&gt;attribute&lt;/name&gt;
32   * &lt;tagclass&gt;org.apache.taglibs.application.AttributeTag&lt;/tagclass&gt;
33   * &lt;bodycontent&gt;empty&lt;/bodycontent&gt;
34   * &lt;info&gt;Output the value of a single attribute.&lt;/info&gt;
35   *   &lt;attribute&gt;
36   *     &lt;name&gt;name&lt;/name&gt;
37   *     &lt;required&gt;true&lt;/required&gt;
38   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
39   *   &lt;/attribute&gt;
40   * </pre>
41   *
42   * @author Morgan Delagrange
43   */
44  
45  public class AttributeTag extends TagSupport
46  {
47      // Name of application attribute
48      private String   name = null;
49  
50      /**
51       * Method called at end of Tag to output attribute value
52       *
53       * @return EVAL_PAGE
54       */
55      public final int doEndTag() throws JspException
56      {
57      Object   value =
58          pageContext.getServletContext().getAttribute(name);
59      if( value == null )
60          value = "";
61  
62      try {
63          pageContext.getOut().write(value.toString());
64      } catch(Exception   e) {
65          throw new JspException("IO Error: " + e.getMessage());
66      }
67  
68      return EVAL_PAGE;
69      }
70  
71      /**
72       * Set the required tag attribute <b>name</b>. 
73       *
74       * @param String name of application attribute
75       */
76      public final void setName(String   str)
77      {
78      name = str;
79      }
80  
81  }
82
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