DefineTag


1   /*
2    * $Id: DefineTag.java 54929 2004-10-16 16:38:42Z germuska $ 
3    *
4    * Copyright 1999-2004 The Apache Software Foundation.
5    * 
6    * Licensed under the Apache License, Version 2.0 (the "License");
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    * 
10   *      http://www.apache.org/licenses/LICENSE-2.0
11   * 
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  
20  package org.apache.struts.taglib.bean;
21  
22  
23  import javax.servlet.jsp.JspException  ;
24  import javax.servlet.jsp.PageContext  ;
25  import javax.servlet.jsp.tagext.BodyTagSupport  ;
26  
27  import org.apache.struts.taglib.TagUtils;
28  import org.apache.struts.util.MessageResources;
29  import org.apache.commons.logging.Log;
30  import org.apache.commons.logging.LogFactory;
31  
32  
33  /**
34   * Define a scripting variable based on the value(s) of the specified
35   * bean property.
36   *
37   * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
38   */
39  
40  public class DefineTag extends BodyTagSupport   {
41  
42      /**
43        * Commons logging instance.
44        */
45       private static final Log log = LogFactory.getLog(DefineTag.class);
46  
47      // ---------------------------------------------------- Protected variables
48  
49      /**
50       * The message resources for this package.
51       */
52      protected static MessageResources messages =
53          MessageResources.getMessageResources
54          ("org.apache.struts.taglib.bean.LocalStrings");
55  
56  
57      /**
58       * The body content of this tag (if any).
59       */
60      protected String   body = null;
61  
62  
63      // ------------------------------------------------------------- Properties
64  
65  
66      /**
67       * The name of the scripting variable that will be exposed as a page
68       * scope attribute.
69       */
70      protected String   id = null;
71  
72      public String   getId() {
73          return (this.id);
74      }
75  
76      public void setId(String   id) {
77          this.id = id;
78      }
79  
80  
81      /**
82       * The name of the bean owning the property to be exposed.
83       */
84      protected String   name = null;
85  
86      public String   getName() {
87          return (this.name);
88      }
89  
90      public void setName(String   name) {
91          this.name = name;
92      }
93  
94  
95      /**
96       * The name of the property to be retrieved.
97       */
98      protected String   property = null;
99  
100     public String   getProperty() {
101         return (this.property);
102     }
103 
104     public void setProperty(String   property) {
105         this.property = property;
106     }
107 
108 
109     /**
110      * The scope within which to search for the specified bean.
111      */
112     protected String   scope = null;
113 
114     public String   getScope() {
115         return (this.scope);
116     }
117 
118     public void setScope(String   scope) {
119         this.scope = scope;
120     }
121 
122 
123     /**
124      * The scope within which the newly defined bean will be creatd.
125      */
126     protected String   toScope = null;
127 
128     public String   getToScope() {
129         return (this.toScope);
130     }
131 
132     public void setToScope(String   toScope) {
133         this.toScope = toScope;
134     }
135 
136 
137     /**
138      * The fully qualified Java class name of the value to be exposed.
139      */
140     protected String   type = null;
141 
142     public String   getType() {
143         return (this.type);
144     }
145 
146     public void setType(String   type) {
147         this.type = type;
148     }
149 
150 
151     /**
152      * The (String) value to which the defined bean will be set.
153      */
154     protected String   value = null;
155 
156     public String   getValue() {
157         return (this.value);
158     }
159 
160     public void setValue(String   value) {
161         this.value = value;
162     }
163 
164 
165     // --------------------------------------------------------- Public Methods
166 
167 
168     /**
169      * Check if we need to evaluate the body of the tag
170      *
171      * @exception JspException if a JSP exception has occurred
172      */
173     public int doStartTag() throws JspException   {
174        
175         return (EVAL_BODY_TAG);
176 
177     }
178 
179 
180     /**
181      * Save the body content of this tag (if any), or throw a JspException
182      * if the value was already defined.
183      *
184      * @exception JspException if value was defined by an attribute
185      */
186     public int doAfterBody() throws JspException   {
187 
188         if (bodyContent != null) {
189             body = bodyContent.getString();
190             if (body != null) {
191                 body = body.trim();
192             }
193             if (body.length() < 1) {
194                 body = null;
195             }
196         }
197         return (SKIP_BODY);
198 
199     }
200 
201 
202     /**
203      * Retrieve the required property and expose it as a scripting variable.
204      *
205      * @exception JspException if a JSP exception has occurred
206      */
207     public int doEndTag() throws JspException   {
208 
209         // Enforce restriction on ways to declare the new value
210         int n = 0;
211         if (this.body != null) {
212             n++;
213         }
214         if (this.name != null) {
215             n++;
216         }
217         if (this.value != null) {
218             n++;
219         }
220         if (n != 1) {
221             JspException   e =
222                 new JspException  (messages.getMessage("define.value"));
223             TagUtils.getInstance().saveException(pageContext, e);
224             throw e;
225         }
226 
227         // Retrieve the required property value
228         Object   value = this.value;
229         if ((value == null) && (name != null)) {
230             value = TagUtils.getInstance().lookup(pageContext, name, property, scope);
231         }
232         if ((value == null) && (body != null)) {
233             value = body;
234         }
235         if (value == null) {
236             JspException   e =
237                 new JspException  (messages.getMessage("define.null"));
238             TagUtils.getInstance().saveException(pageContext, e);
239             throw e;
240         }
241 
242         // Expose this value as a scripting variable
243         int inScope = PageContext.PAGE_SCOPE;
244         try {
245             if (toScope != null) {
246                 inScope = TagUtils.getInstance().getScope(toScope);
247             }
248         } catch (JspException   e) {
249             log.warn("toScope was invalid name so we default to PAGE_SCOPE",e);
250         }
251             
252         pageContext.setAttribute(id, value, inScope);
253 
254         // Continue processing this page
255         return (EVAL_PAGE);
256 
257     }
258 
259     /**
260      * Release all allocated resources.
261      */
262     public void release() {
263 
264         super.release();
265         body = null;
266         id = null;
267         name = null;
268         property = null;
269         scope = null;
270         toScope = "page";
271         type = null;
272         value = null;
273 
274     }
275 
276 
277 }
278
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