SetRootRule


1   /* $Id: SetRootRule.java 155412 2005-02-26 12:58:36Z dirkv $
2    *
3    * Copyright 2002-2004 The Apache Software Foundation.
4    * 
5    * Licensed under the Apache License, Version 2.0 (the "License");
6    * you may not use this file except in compliance with the License.
7    * 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.commons.digester;
20  
21  
22  import org.apache.commons.beanutils.MethodUtils;
23  
24  
25  /**
26   * <p>Rule implementation that calls a method on the root object on the stack,
27   * passing the top object (child) as an argument.
28   * It is important to remember that this rule acts on <code>end</code>.</p>
29   *
30   * <p>This rule now supports more flexible method matching by default.
31   * It is possible that this may break (some) code 
32   * written against release 1.1.1 or earlier.
33   * See {@link #isExactMatch()} for more details.</p>
34   */
35  
36  public class SetRootRule extends Rule {
37  
38  
39      // ----------------------------------------------------------- Constructors
40  
41  
42      /**
43       * Construct a "set root" rule with the specified method name.  The
44       * method's argument type is assumed to be the class of the
45       * child object.
46       *
47       * @param digester The associated Digester
48       * @param methodName Method name of the parent method to call
49       *
50       * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
51       * Use {@link #SetRootRule(String methodName)} instead.
52       */
53      public SetRootRule(Digester digester, String   methodName) {
54  
55          this(methodName);
56  
57      }
58  
59  
60      /**
61       * Construct a "set root" rule with the specified method name.
62       *
63       * @param digester The associated Digester
64       * @param methodName Method name of the parent method to call
65       * @param paramType Java class of the parent method's argument
66       *  (if you wish to use a primitive type, specify the corresonding
67       *  Java wrapper class instead, such as <code>java.lang.Boolean</code>
68       *  for a <code>boolean</code> parameter)
69       *
70       * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
71       * Use {@link #SetRootRule(String methodName,String paramType)} instead.
72       */
73      public SetRootRule(Digester digester, String   methodName,
74                         String   paramType) {
75  
76          this(methodName, paramType);
77  
78      }
79  
80      /**
81       * Construct a "set root" rule with the specified method name.  The
82       * method's argument type is assumed to be the class of the
83       * child object.
84       *
85       * @param methodName Method name of the parent method to call
86       */
87      public SetRootRule(String   methodName) {
88  
89          this(methodName, null);
90  
91      }
92  
93  
94      /**
95       * Construct a "set root" rule with the specified method name.
96       *
97       * @param methodName Method name of the parent method to call
98       * @param paramType Java class of the parent method's argument
99       *  (if you wish to use a primitive type, specify the corresonding
100      *  Java wrapper class instead, such as <code>java.lang.Boolean</code>
101      *  for a <code>boolean</code> parameter)
102      */
103     public SetRootRule(String   methodName,
104                        String   paramType) {
105 
106         this.methodName = methodName;
107         this.paramType = paramType;
108 
109     }
110 
111     // ----------------------------------------------------- Instance Variables
112 
113 
114     /**
115      * The method name to call on the parent object.
116      */
117     protected String   methodName = null;
118 
119 
120     /**
121      * The Java class name of the parameter type expected by the method.
122      */
123     protected String   paramType = null;
124     
125     /**
126      * Should we use exact matching. Default is no.
127      */
128     protected boolean useExactMatch = false;
129 
130 
131     // --------------------------------------------------------- Public Methods
132 
133 
134     /**
135      * <p>Is exact matching being used.</p>
136      *
137      * <p>This rule uses <code>org.apache.commons.beanutils.MethodUtils</code> 
138      * to introspect the relevent objects so that the right method can be called.
139      * Originally, <code>MethodUtils.invokeExactMethod</code> was used.
140      * This matches methods very strictly 
141      * and so may not find a matching method when one exists.
142      * This is still the behaviour when exact matching is enabled.</p>
143      *
144      * <p>When exact matching is disabled, <code>MethodUtils.invokeMethod</code> is used.
145      * This method finds more methods but is less precise when there are several methods 
146      * with correct signatures.
147      * So, if you want to choose an exact signature you might need to enable this property.</p>
148      *
149      * <p>The default setting is to disable exact matches.</p>
150      *
151      * @return true iff exact matching is enabled
152      * @since Digester Release 1.1.1
153      */
154     public boolean isExactMatch() {
155     
156         return useExactMatch;
157     }
158     
159     
160     /**
161      * <p>Set whether exact matching is enabled.</p>
162      *
163      * <p>See {@link #isExactMatch()}.</p>
164      *
165      * @param useExactMatch should this rule use exact method matching
166      * @since Digester Release 1.1.1
167      */
168     public void setExactMatch(boolean useExactMatch) {
169 
170         this.useExactMatch = useExactMatch;
171     }
172 
173     /**
174      * Process the end of this element.
175      */
176     public void end() throws Exception   {
177 
178         // Identify the objects to be used
179         Object   child = digester.peek(0);
180         Object   parent = digester.root;
181         if (digester.log.isDebugEnabled()) {
182             if (parent == null) {
183                 digester.log.debug("[SetRootRule]{" + digester.match +
184                         "} Call [NULL ROOT]." +
185                         methodName + "(" + child + ")");
186             } else {
187                 digester.log.debug("[SetRootRule]{" + digester.match +
188                         "} Call " + parent.getClass().getName() + "." +
189                         methodName + "(" + child + ")");
190             }
191         }
192 
193         // Call the specified method
194         Class   paramTypes[] = new Class  [1];
195         if (paramType != null) {
196             paramTypes[0] =
197                     digester.getClassLoader().loadClass(paramType);
198         } else {
199             paramTypes[0] = child.getClass();
200         }
201         
202         if (useExactMatch) {
203         
204             MethodUtils.invokeExactMethod(parent, methodName,
205                 new Object  []{ child }, paramTypes);
206                 
207         } else {
208         
209             MethodUtils.invokeMethod(parent, methodName,
210                 new Object  []{ child }, paramTypes);
211         
212         }
213     }
214 
215 
216     /**
217      * Render a printable version of this Rule.
218      */
219     public String   toString() {
220 
221         StringBuffer   sb = new StringBuffer  ("SetRootRule[");
222         sb.append("methodName=");
223         sb.append(methodName);
224         sb.append(", paramType=");
225         sb.append(paramType);
226         sb.append("]");
227         return (sb.toString());
228 
229     }
230 
231 
232 }
233
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