KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > net > sourceforge > cruisecontrol > util > EmptyElementFilter


1 /********************************************************************************
2  * CruiseControl, a Continuous Integration Toolkit
3  * Copyright (c) 2001, ThoughtWorks, Inc.
4  * 651 W Washington Ave. Suite 600
5  * Chicago, IL 60661 USA
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * + Redistributions of source code must retain the above copyright
13  * notice, this list of conditions and the following disclaimer.
14  *
15  * + Redistributions in binary form must reproduce the above
16  * copyright notice, this list of conditions and the following
17  * disclaimer in the documentation and/or other materials provided
18  * with the distribution.
19  *
20  * + Neither the name of ThoughtWorks, Inc., CruiseControl, nor the
21  * names of its contributors may be used to endorse or promote
22  * products derived from this software without specific prior
23  * written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
29  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
30  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
32  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
33  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
34  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
35  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  ********************************************************************************/
37
38 package net.sourceforge.cruisecontrol.util;
39
40 import org.apache.log4j.Logger;
41 import org.xml.sax.Attributes JavaDoc;
42 import org.xml.sax.SAXException JavaDoc;
43 import org.xml.sax.XMLReader JavaDoc;
44 import org.xml.sax.helpers.XMLFilterImpl JavaDoc;
45
46 /**
47  * This filter deletes elements without child nodes (text or elements) with
48  * the given tagname.
49  * It is used by the AntBuilder to get rid of empty tags
50  * generated by Ant's XmlLogger, like empty messages and tasks.
51  *
52  * @author <a HREF="mailto:joriskuipers@xs4all.nl">Joris Kuipers</a>
53  */
54 public class EmptyElementFilter extends XMLFilterImpl JavaDoc {
55
56     private static final Logger LOG = Logger.getLogger(EmptyElementFilter.class);
57
58     private final String JavaDoc tagName;
59
60     private boolean checkingTag = false;
61     // atts for storing the Element info
62 private String JavaDoc messageUri;
63     private String JavaDoc messageQName;
64     private Attributes JavaDoc messageAtts;
65
66     /**
67      * Constructor for EmptyElementFilter.
68      */
69     public EmptyElementFilter(String JavaDoc tagName) {
70         super();
71         this.tagName = tagName;
72     }
73
74     /**
75      * Constructor for EmptyElementFilter.
76      * @param arg0
77      */
78     public EmptyElementFilter(String JavaDoc tagName, XMLReader JavaDoc arg0) {
79         super(arg0);
80         this.tagName = tagName;
81     }
82
83     /**
84      * @see org.xml.sax.ContentHandler#characters(char[], int, int)
85      */
86     public void characters(char[] ch, int start, int length) throws SAXException JavaDoc {
87         if (checkingTag) {
88             cancelCheck();
89         }
90         super.characters(ch, start, length);
91     }
92
93     /**
94      * @see org.xml.sax.ContentHandler#endElement(String, String, String)
95      */
96     public void endElement(String JavaDoc uri, String JavaDoc localName, String JavaDoc qName) throws SAXException JavaDoc {
97         if (checkingTag) {
98             // localName must be tagName now, and we're dealing with an empty tag
99 checkingTag = false;
100             LOG.debug("Skipping empty <" + localName + ">-tag");
101         } else {
102             super.endElement(uri, localName, qName);
103         }
104     }
105
106     /**
107      * @see org.xml.sax.ContentHandler#startElement(String, String, String, Attributes)
108      */
109     public void startElement(String JavaDoc uri, String JavaDoc localName, String JavaDoc qName, Attributes JavaDoc atts) throws SAXException JavaDoc {
110         if (checkingTag) {
111             cancelCheck();
112         }
113         if (localName.equals(tagName)) {
114             // hold the delegation until we're sure this is not an empty tag
115 checkingTag = true;
116             messageUri = uri;
117             messageQName = qName;
118             messageAtts = atts;
119         } else {
120             super.startElement(uri, localName, qName, atts);
121         }
122     }
123     
124     private void cancelCheck() throws SAXException JavaDoc {
125         // delegate the event that we've held back and stop checking
126 super.startElement(messageUri, tagName, messageQName, messageAtts);
127         checkingTag = false;
128     }
129
130 }
131
Popular Tags