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.configuration2;
19
20 import org.apache.commons.configuration2.tree.ConfigurationNodeVisitorAdapter;
21 import org.apache.commons.configuration2.tree.NodeHandler;
22 import org.apache.commons.configuration2.tree.NodeTreeWalker;
23 import org.xml.sax.Attributes;
24 import org.xml.sax.helpers.AttributesImpl;
25
26 /**
27 * <p>
28 * A specialized SAX2 XML parser that "parses" hierarchical configuration objects.
29 * </p>
30 * <p>
31 * This class mimics to be a SAX conform XML parser. Instead of parsing XML documents it processes a
32 * {@code Configuration} object and generates SAX events for the single properties defined there. This enables the whole
33 * world of XML processing for configuration objects.
34 * </p>
35 * <p>
36 * The {@code HierarchicalConfiguration} object to be parsed can be specified using a constructor or the
37 * {@code setConfiguration()} method. This object will be processed by the {@code parse()} methods. Note that these
38 * methods ignore their argument.
39 * </p>
40 *
41 * @param <T> the type of the nodes supported by this reader
42 */
43 public class HierarchicalConfigurationXMLReader<T> extends ConfigurationXMLReader {
44 /** Stores the configuration object to be parsed. */
45 private HierarchicalConfiguration<T> configuration;
46
47 /**
48 * Creates a new instance of {@code HierarchicalConfigurationXMLReader}.
49 */
50 public HierarchicalConfigurationXMLReader() {
51 }
52
53 /**
54 * Creates a new instance of {@code HierarchicalConfigurationXMLReader} and sets the configuration to be parsed.
55 *
56 * @param config the configuration object
57 */
58 public HierarchicalConfigurationXMLReader(final HierarchicalConfiguration<T> config) {
59 this();
60 setConfiguration(config);
61 }
62
63 /**
64 * Gets the configuration object to be parsed.
65 *
66 * @return the configuration object to be parsed
67 */
68 public HierarchicalConfiguration<T> getConfiguration() {
69 return configuration;
70 }
71
72 /**
73 * Sets the configuration object to be parsed.
74 *
75 * @param config the configuration object to be parsed
76 */
77 public void setConfiguration(final HierarchicalConfiguration<T> config) {
78 configuration = config;
79 }
80
81 /**
82 * Gets the configuration object to be processed.
83 *
84 * @return the actual configuration object
85 */
86 @Override
87 public Configuration getParsedConfiguration() {
88 return getConfiguration();
89 }
90
91 /**
92 * Processes the actual configuration object to generate SAX parsing events.
93 */
94 @Override
95 protected void processKeys() {
96 final NodeHandler<T> nodeHandler = getConfiguration().getNodeModel().getNodeHandler();
97 NodeTreeWalker.INSTANCE.walkDFS(nodeHandler.getRootNode(), new SAXVisitor(), nodeHandler);
98 }
99
100 /**
101 * A specialized visitor class for generating SAX events for a hierarchical node structure.
102 */
103 private final class SAXVisitor extends ConfigurationNodeVisitorAdapter<T> {
104 /** Constant for the attribute type. */
105 private static final String ATTR_TYPE = "CDATA";
106
107 /**
108 * Visits the specified node after its children have been processed.
109 *
110 * @param node the actual node
111 * @param handler the node handler
112 */
113 @Override
114 public void visitAfterChildren(final T node, final NodeHandler<T> handler) {
115 fireElementEnd(nodeName(node, handler));
116 }
117
118 /**
119 * Visits the specified node.
120 *
121 * @param node the actual node
122 * @param handler the node handler
123 */
124 @Override
125 public void visitBeforeChildren(final T node, final NodeHandler<T> handler) {
126 fireElementStart(nodeName(node, handler), fetchAttributes(node, handler));
127
128 final Object value = handler.getValue(node);
129 if (value != null) {
130 fireCharacters(value.toString());
131 }
132 }
133
134 /**
135 * Checks if iteration should be terminated. This implementation stops iteration after an exception has occurred.
136 *
137 * @return a flag if iteration should be stopped
138 */
139 @Override
140 public boolean terminate() {
141 return getException() != null;
142 }
143
144 /**
145 * Returns an object with all attributes for the specified node.
146 *
147 * @param node the current node
148 * @param handler the node handler
149 * @return an object with all attributes of this node
150 */
151 protected Attributes fetchAttributes(final T node, final NodeHandler<T> handler) {
152 final AttributesImpl attrs = new AttributesImpl();
153
154 handler.getAttributes(node).forEach(attr -> {
155 final Object value = handler.getAttributeValue(node, attr);
156 if (value != null) {
157 attrs.addAttribute(NS_URI, attr, attr, ATTR_TYPE, value.toString());
158 }
159 });
160
161 return attrs;
162 }
163
164 /**
165 * Helper method for determining the name of a node. If a node has no name (which is true for the root node), the
166 * specified default name will be used.
167 *
168 * @param node the node to be checked
169 * @param handler the node handler
170 * @return the name for this node
171 */
172 private String nodeName(final T node, final NodeHandler<T> handler) {
173 final String nodeName = handler.nodeName(node);
174 return nodeName == null ? getRootName() : nodeName;
175 }
176 }
177 }