001/* $Id: ObjectCreateRule.java 471661 2006-11-06 08:09:25Z skitching $
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements.  See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License.  You may obtain a copy of the License at
009 * 
010 *      http://www.apache.org/licenses/LICENSE-2.0
011 * 
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */ 
018
019
020package org.apache.commons.digester;
021
022
023import org.xml.sax.Attributes;
024
025
026/**
027 * Rule implementation that creates a new object and pushes it
028 * onto the object stack.  When the element is complete, the
029 * object will be popped
030 */
031
032public class ObjectCreateRule extends Rule {
033
034
035    // ----------------------------------------------------------- Constructors
036
037
038    /**
039     * Construct an object create rule with the specified class name.
040     *
041     * @param digester The associated Digester
042     * @param className Java class name of the object to be created
043     *
044     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
045     * Use {@link #ObjectCreateRule(String className)} instead.
046     */
047    public ObjectCreateRule(Digester digester, String className) {
048
049        this(className);
050
051    }
052
053
054    /**
055     * Construct an object create rule with the specified class.
056     *
057     * @param digester The associated Digester
058     * @param clazz Java class name of the object to be created
059     *
060     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
061     * Use {@link #ObjectCreateRule(Class clazz)} instead.
062     */
063    public ObjectCreateRule(Digester digester, Class clazz) {
064
065        this(clazz);
066
067    }
068
069
070    /**
071     * Construct an object create rule with the specified class name and an
072     * optional attribute name containing an override.
073     *
074     * @param digester The associated Digester
075     * @param className Java class name of the object to be created
076     * @param attributeName Attribute name which, if present, contains an
077     *  override of the class name to create
078     *
079     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
080     * Use {@link #ObjectCreateRule(String className, String attributeName)} instead.
081     */
082    public ObjectCreateRule(Digester digester, String className,
083                            String attributeName) {
084
085        this (className, attributeName);
086
087    }
088
089
090    /**
091     * Construct an object create rule with the specified class and an
092     * optional attribute name containing an override.
093     *
094     * @param digester The associated Digester
095     * @param attributeName Attribute name which, if present, contains an
096     * @param clazz Java class name of the object to be created
097     *  override of the class name to create
098     *
099     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
100     * Use {@link #ObjectCreateRule(String attributeName, Class clazz)} instead.
101     */
102    public ObjectCreateRule(Digester digester,
103                            String attributeName,
104                            Class clazz) {
105
106        this(attributeName, clazz);
107
108    }
109
110    /**
111     * Construct an object create rule with the specified class name.
112     *
113     * @param className Java class name of the object to be created
114     */
115    public ObjectCreateRule(String className) {
116
117        this(className, (String) null);
118
119    }
120
121
122    /**
123     * Construct an object create rule with the specified class.
124     *
125     * @param clazz Java class name of the object to be created
126     */
127    public ObjectCreateRule(Class clazz) {
128
129        this(clazz.getName(), (String) null);
130
131    }
132
133
134    /**
135     * Construct an object create rule with the specified class name and an
136     * optional attribute name containing an override.
137     *
138     * @param className Java class name of the object to be created
139     * @param attributeName Attribute name which, if present, contains an
140     *  override of the class name to create
141     */
142    public ObjectCreateRule(String className,
143                            String attributeName) {
144
145        this.className = className;
146        this.attributeName = attributeName;
147
148    }
149
150
151    /**
152     * Construct an object create rule with the specified class and an
153     * optional attribute name containing an override.
154     *
155     * @param attributeName Attribute name which, if present, contains an
156     * @param clazz Java class name of the object to be created
157     *  override of the class name to create
158     */
159    public ObjectCreateRule(String attributeName,
160                            Class clazz) {
161
162        this(clazz.getName(), attributeName);
163
164    }
165
166    // ----------------------------------------------------- Instance Variables
167
168
169    /**
170     * The attribute containing an override class name if it is present.
171     */
172    protected String attributeName = null;
173
174
175    /**
176     * The Java class name of the object to be created.
177     */
178    protected String className = null;
179
180
181    // --------------------------------------------------------- Public Methods
182
183
184    /**
185     * Process the beginning of this element.
186     *
187     * @param attributes The attribute list of this element
188     */
189    public void begin(Attributes attributes) throws Exception {
190
191        // Identify the name of the class to instantiate
192        String realClassName = className;
193        if (attributeName != null) {
194            String value = attributes.getValue(attributeName);
195            if (value != null) {
196                realClassName = value;
197            }
198        }
199        if (digester.log.isDebugEnabled()) {
200            digester.log.debug("[ObjectCreateRule]{" + digester.match +
201                    "}New " + realClassName);
202        }
203
204        // Instantiate the new object and push it on the context stack
205        Class clazz = digester.getClassLoader().loadClass(realClassName);
206        Object instance = clazz.newInstance();
207        digester.push(instance);
208
209    }
210
211
212    /**
213     * Process the end of this element.
214     */
215    public void end() throws Exception {
216
217        Object top = digester.pop();
218        if (digester.log.isDebugEnabled()) {
219            digester.log.debug("[ObjectCreateRule]{" + digester.match +
220                    "} Pop " + top.getClass().getName());
221        }
222
223    }
224
225
226    /**
227     * Render a printable version of this Rule.
228     */
229    public String toString() {
230
231        StringBuffer sb = new StringBuffer("ObjectCreateRule[");
232        sb.append("className=");
233        sb.append(className);
234        sb.append(", attributeName=");
235        sb.append(attributeName);
236        sb.append("]");
237        return (sb.toString());
238
239    }
240
241
242}