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1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.commons.jelly.tags.define;
18  
19  import java.util.HashMap;
20  import java.util.Map;
21  
22  import org.apache.commons.beanutils.DynaClass;
23  import org.apache.commons.jelly.JellyTagException;
24  import org.apache.commons.jelly.MissingAttributeException;
25  import org.apache.commons.jelly.Tag;
26  import org.apache.commons.jelly.XMLOutput;
27  import org.apache.commons.jelly.impl.Attribute;
28  import org.apache.commons.jelly.impl.DynamicDynaBeanTag;
29  import org.apache.commons.jelly.impl.TagFactory;
30  import org.apache.commons.logging.Log;
31  import org.apache.commons.logging.LogFactory;
32  import org.xml.sax.Attributes;
33  
34  /***
35   * Binds a Java bean to the given named Jelly tag so that the attributes of
36   * the tag set the bean properties..
37   *
38   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
39   * @version $Revision: 155420 $
40   */
41  public class DynaBeanTag extends DefineTagSupport {
42  
43      /*** The Log to which logging calls will be made. */
44      private static final Log log = LogFactory.getLog(DynaBeanTag.class);
45  
46      /*** An empty Map as I think Collections.EMPTY_MAP is only JDK 1.3 onwards */
47      private static final Map EMPTY_MAP = new HashMap();
48  
49      /*** the name of the tag to create */
50      private String name;
51  
52      /*** the DyanClass to bind to the tag */
53      private DynaClass dynaClass;
54  
55      /*** the name of the attribute used for the variable name */
56      private String varAttribute = "var";
57  
58      /*** the attribute definitions for this dynamic tag */
59      private Map attributes;
60  
61      /***
62       * Adds a new attribute definition to this dynamic tag
63       */
64      public void addAttribute(Attribute attribute) {
65          if ( attributes == null ) {
66              attributes = new HashMap();
67          }
68          attributes.put( attribute.getName(), attribute );
69      }
70  
71      // Tag interface
72      //-------------------------------------------------------------------------
73      public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
74          invokeBody(output);
75  
76          if (name == null) {
77              throw new MissingAttributeException("name");
78          }
79          if (dynaClass == null) {
80              throw new MissingAttributeException("dynaClass");
81          }
82  
83          final DynaClass theDynaClass = dynaClass;
84          final Map beanAttributes = (attributes != null) ? attributes : EMPTY_MAP;
85  
86          TagFactory factory = new TagFactory() {
87              public Tag createTag(String name, Attributes attributes) {
88                  return  new DynamicDynaBeanTag(theDynaClass, beanAttributes, varAttribute);
89              }
90          };
91          getTagLibrary().registerBeanTag(name, factory);
92  
93          // now lets clear the attributes for next invocation and help the GC
94          attributes = null;
95      }
96  
97  
98      // Properties
99      //-------------------------------------------------------------------------
100 
101     /***
102      * Sets the name of the tag to create
103      */
104     public void setName(String name) {
105         this.name = name;
106     }
107 
108     /***
109      * Sets the name of the attribute used to define the bean variable that this dynamic
110      * tag will output its results as. This defaults to 'var' though this property
111      * can be used to change this if it conflicts with a bean property called 'var'.
112      */
113     public void setVarAttribute(String varAttribute) {
114         this.varAttribute = varAttribute;
115     }
116 
117     /***
118      * Returns the dynaClass.
119      * @return DynaClass
120      */
121     public DynaClass getDynaClass() {
122         return dynaClass;
123     }
124 
125     /***
126      * Sets the {@link DynaClass} which will be bound to this dynamic tag.
127      */
128     public void setDynaClass(DynaClass dynaClass) {
129         this.dynaClass = dynaClass;
130     }
131 
132 }