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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.configuration;
19  
20  import java.util.Iterator;
21  
22  import org.apache.commons.configuration.HierarchicalConfiguration.Node;
23  import org.xml.sax.Attributes;
24  import org.xml.sax.helpers.AttributesImpl;
25  
26  /***
27   * <p>A specialized SAX2 XML parser that "parses" hierarchical
28   * configuration objects.</p>
29   * <p>This class mimics to be a SAX conform XML parser. Instead of parsing
30   * XML documents it processes a <code>Configuration</code> object and
31   * generates SAX events for the single properties defined there. This enables
32   * the whole world of XML processing for configuration objects.</p>
33   * <p>The <code>HierarchicalConfiguration</code> object to be parsed can be
34   * specified using a constructor or the <code>setConfiguration()</code> method.
35   * This object will be processed by the <code>parse()</code> methods. Note
36   * that these methods ignore their argument.</p>
37   *
38   * @author <a href="mailto:oliver.heger@t-online.de">Oliver Heger</a>
39   * @version $Id: HierarchicalConfigurationXMLReader.java 439648 2006-09-02 20:42:10Z oheger $
40   */
41  public class HierarchicalConfigurationXMLReader extends ConfigurationXMLReader
42  {
43      /*** Stores the configuration object to be parsed.*/
44      private HierarchicalConfiguration configuration;
45  
46      /***
47       * Creates a new instance of
48       * <code>HierarchicalConfigurationXMLReader</code>.
49       */
50      public HierarchicalConfigurationXMLReader()
51      {
52          super();
53      }
54  
55      /***
56       * Creates a new instance of
57       * <code>HierarchicalConfigurationXMLReader</code> and sets the
58       * configuration to be parsed.
59       *
60       * @param config the configuration object
61       */
62      public HierarchicalConfigurationXMLReader(HierarchicalConfiguration config)
63      {
64          this();
65          setConfiguration(config);
66      }
67  
68      /***
69       * Returns the configuration object to be parsed.
70       *
71       * @return the configuration object to be parsed
72       */
73      public HierarchicalConfiguration getConfiguration()
74      {
75          return configuration;
76      }
77  
78      /***
79       * Sets the configuration object to be parsed.
80       *
81       * @param config the configuration object to be parsed
82       */
83      public void setConfiguration(HierarchicalConfiguration config)
84      {
85          configuration = config;
86      }
87  
88      /***
89       * Returns the configuration object to be processed.
90       *
91       * @return the actual configuration object
92       */
93      public Configuration getParsedConfiguration()
94      {
95          return getConfiguration();
96      }
97  
98      /***
99       * Processes the actual configuration object to generate SAX parsing events.
100      */
101     protected void processKeys()
102     {
103         getConfiguration().getRoot().visit(new SAXVisitor(), null);
104     }
105 
106     /***
107      * A specialized visitor class for generating SAX events for a
108      * hierarchical node structure.
109      *
110      */
111     class SAXVisitor extends HierarchicalConfiguration.NodeVisitor
112     {
113         /*** Constant for the attribute type.*/
114         private static final String ATTR_TYPE = "CDATA";
115 
116         /***
117          * Visits the specified node after its children have been processed.
118          *
119          * @param node the actual node
120          * @param key the key of this node
121          */
122         public void visitAfterChildren(Node node, ConfigurationKey key)
123         {
124             if (!isAttributeNode(node))
125             {
126                 fireElementEnd(nodeName(node));
127             }
128         }
129 
130         /***
131          * Visits the specified node.
132          *
133          * @param node the actual node
134          * @param key the key of this node
135          */
136         public void visitBeforeChildren(Node node, ConfigurationKey key)
137         {
138             if (!isAttributeNode(node))
139             {
140                 fireElementStart(nodeName(node), fetchAttributes(node));
141 
142                 if (node.getValue() != null)
143                 {
144                     fireCharacters(node.getValue().toString());
145                 }
146             }
147         }
148 
149         /***
150          * Checks if iteration should be terminated. This implementation stops
151          * iteration after an exception has occurred.
152          *
153          * @return a flag if iteration should be stopped
154          */
155         public boolean terminate()
156         {
157             return getException() != null;
158         }
159 
160         /***
161          * Returns an object with all attributes for the specified node.
162          *
163          * @param node the actual node
164          * @return an object with all attributes of this node
165          */
166         protected Attributes fetchAttributes(Node node)
167         {
168             AttributesImpl attrs = new AttributesImpl();
169 
170             for (Iterator it = node.getAttributes().iterator(); it.hasNext();)
171             {
172                 Node child = (Node) it.next();
173                 if (child.getValue() != null)
174                 {
175                     String attr = child.getName();
176                     attrs.addAttribute(NS_URI, attr, attr, ATTR_TYPE, child.getValue().toString());
177                 }
178             }
179 
180             return attrs;
181         }
182 
183         /***
184          * Helper method for determining the name of a node. If a node has no
185          * name (which is true for the root node), the specified default name
186          * will be used.
187          *
188          * @param node the node to be checked
189          * @return the name for this node
190          */
191         private String nodeName(Node node)
192         {
193             return (node.getName() == null) ? getRootName() : node.getName();
194         }
195 
196         /***
197          * Checks if the specified node is an attribute node. In the node
198          * hierarchy attributes are stored as normal child nodes, but with
199          * special names.
200          *
201          * @param node the node to be checked
202          * @return a flag if this is an attribute node
203          */
204         private boolean isAttributeNode(Node node)
205         {
206             return node.isAttribute();
207         }
208     }
209 }