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
19 package org.apache.tomcat.util.digester;
20
21
22 import org.xml.sax.Attributes;
23
24
25 /**
26 * Rule implementation that creates a new object and pushes it
27 * onto the object stack. When the element is complete, the
28 * object will be popped
29 */
30
31 public class ObjectCreateRule extends Rule {
32
33
34 // ----------------------------------------------------------- Constructors
35
36
37 /**
38 * Construct an object create rule with the specified class name.
39 *
40 * @param className Java class name of the object to be created
41 */
42 public ObjectCreateRule(String className) {
43
44 this(className, null);
45
46 }
47
48
49 /**
50 * Construct an object create rule with the specified class name and an
51 * optional attribute name containing an override.
52 *
53 * @param className Java class name of the object to be created
54 * @param attributeName Attribute name which, if present, contains an
55 * override of the class name to create
56 */
57 public ObjectCreateRule(String className,
58 String attributeName) {
59
60 this.className = className;
61 this.attributeName = attributeName;
62
63 }
64
65
66 // ----------------------------------------------------- Instance Variables
67
68 /**
69 * The attribute containing an override class name if it is present.
70 */
71 protected String attributeName = null;
72
73
74 /**
75 * The Java class name of the object to be created.
76 */
77 protected String className = null;
78
79
80 // --------------------------------------------------------- Public Methods
81
82
83 /**
84 * Process the beginning of this element.
85 *
86 * @param namespace the namespace URI of the matching element, or an
87 * empty string if the parser is not namespace aware or the element has
88 * no namespace
89 * @param name the local name if the parser is namespace aware, or just
90 * the element name otherwise
91 * @param attributes The attribute list for this element
92 */
93 @Override
94 public void begin(String namespace, String name, Attributes attributes)
95 throws Exception {
96
97 String realClassName = getRealClassName(attributes);
98
99 if (realClassName == null) {
100 throw new NullPointerException(sm.getString("rule.noClassName", namespace, name));
101 }
102
103 // Instantiate the new object and push it on the context stack
104 Class<?> clazz = digester.getClassLoader().loadClass(realClassName);
105 Object instance = clazz.getConstructor().newInstance();
106 digester.push(instance);
107 }
108
109
110 /**
111 * Return the actual class name of the class to be instantiated.
112 * @param attributes The attribute list for this element
113 * @return the class name
114 */
115 protected String getRealClassName(Attributes attributes) {
116 // Identify the name of the class to instantiate
117 String realClassName = className;
118 if (attributeName != null) {
119 String value = attributes.getValue(attributeName);
120 if (value != null) {
121 realClassName = value;
122 }
123 }
124 return realClassName;
125 }
126
127
128 /**
129 * Process the end of this element.
130 *
131 * @param namespace the namespace URI of the matching element, or an
132 * empty string if the parser is not namespace aware or the element has
133 * no namespace
134 * @param name the local name if the parser is namespace aware, or just
135 * the element name otherwise
136 */
137 @Override
138 public void end(String namespace, String name) throws Exception {
139
140 Object top = digester.pop();
141 if (digester.log.isDebugEnabled()) {
142 digester.log.debug("[ObjectCreateRule]{" + digester.match +
143 "} Pop " + top.getClass().getName());
144 }
145
146 }
147
148
149 /**
150 * Render a printable version of this Rule.
151 */
152 @Override
153 public String toString() {
154 StringBuilder sb = new StringBuilder("ObjectCreateRule[");
155 sb.append("className=");
156 sb.append(className);
157 sb.append(", attributeName=");
158 sb.append(attributeName);
159 sb.append("]");
160 return sb.toString();
161 }
162
163
164 }
165