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Java > Open Source Codes > org > apache > taglibs > i18n > IfndefTag


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.i18n;
18
19 import java.io.IOException JavaDoc;
20
21 import java.util.ResourceBundle JavaDoc;
22
23 import javax.servlet.jsp.JspException JavaDoc;
24 import javax.servlet.jsp.PageContext JavaDoc;
25 import javax.servlet.jsp.tagext.BodyTag JavaDoc;
26 import javax.servlet.jsp.tagext.BodyTagSupport JavaDoc;
27
28
29 /**
30  * This class implements body tag that allows you to use a resource bundle
31  * to internationalize content in a web page. If a value is found in the
32  * resource bundle for the required "key" attribute, then the enclosed JSP
33  * is evaluated, otherwise, it is skipped.
34  * <P>
35  * The ifdef and ifndef tags allow the JSP author to conditionally evaluate
36  * sections of a JSP based on whether or not a value is provided for the
37  * given key.
38  * <P>
39  * <H2>Examples</H2>
40  * <PRE>
41  * &lt;i18n:bundle baseName="test"/&gt;
42  * &lt;i18n:ifndef key="test"&gt;
43  * misc html and jsp
44  * &lt;/i18n:ifndef&gt;
45  * etc...
46  * </PRE>
47  * <P>
48  *
49  * @author <a HREF="mailto:tdawson@wamnet.com">Tim Dawson</a>
50  *
51  */
52 public class IfndefTag extends ConditionalTagSupport
53 {
54
55     protected static final String JavaDoc _tagname = "i18n:ifndef";
56
57     /**
58      * locates the bundle and tests whether the key has a value
59      */
60     public boolean shouldEvaluate() throws JspException JavaDoc
61     {
62         String JavaDoc value = this.getValue();
63         if ( value == null || value.length() == 0 ) {
64             return true;
65         } else {
66             return false;
67         }
68     }
69
70 }
71
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