SelectTag


1   /*
2    * $Id: SelectTag.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  package org.apache.struts.taglib.html;
20  
21  import java.lang.reflect.InvocationTargetException  ;
22  
23  import javax.servlet.jsp.JspException  ;
24  
25  import org.apache.commons.beanutils.BeanUtils;
26  import org.apache.struts.taglib.TagUtils;
27  import org.apache.struts.util.MessageResources;
28  
29  /**
30   * Custom tag that represents an HTML select element, associated with a
31   * bean property specified by our attributes.  This tag must be nested
32   * inside a form tag.
33   *
34   * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
35   */
36  public class SelectTag extends BaseHandlerTag {
37  
38  
39      // ----------------------------------------------------- Instance Variables
40  
41  
42      /**
43       * The actual values we will match against, calculated in doStartTag().
44       */
45      protected String   match[] = null;
46  
47  
48      /**
49       * The message resources for this package.
50       */
51      protected static MessageResources messages =
52       MessageResources.getMessageResources(Constants.Package + ".LocalStrings");
53  
54  
55      /**
56       * Should multiple selections be allowed.  Any non-null value will
57       * trigger rendering this.
58       */
59      protected String   multiple = null;
60  
61      public String   getMultiple() {
62          return (this.multiple);
63      }
64  
65      public void setMultiple(String   multiple) {
66          this.multiple = multiple;
67      }
68  
69  
70      /**
71       * The name of the bean containing our underlying property.
72       */
73      protected String   name = Constants.BEAN_KEY;
74  
75      public String   getName() {
76          return (this.name);
77      }
78  
79      public void setName(String   name) {
80          this.name = name;
81      }
82  
83  
84      /**
85       * The property name we are associated with.
86       */
87      protected String   property = null;
88  
89  
90      /**
91       * The saved body content of this tag.
92       */
93      protected String   saveBody = null;
94  
95  
96      /**
97       * How many available options should be displayed when this element
98       * is rendered?
99       */
100     protected String   size = null;
101 
102     public String   getSize() {
103         return (this.size);
104     }
105 
106     public void setSize(String   size) {
107         this.size = size;
108     }
109 
110 
111     /**
112      * The value to compare with for marking an option selected.
113      */
114     protected String   value = null;
115 
116 
117     // ------------------------------------------------------------- Properties
118 
119 
120     /**
121      * Does the specified value match one of those we are looking for?
122      *
123      * @param value Value to be compared.
124      */
125     public boolean isMatched(String   value) {
126         if ((this.match == null) || (value == null)) {
127             return false;
128         }
129         
130         for (int i = 0; i < this.match.length; i++) {
131             if (value.equals(this.match[i]))
132                 return true;
133         }
134         
135         return false;
136     }
137 
138 
139     /**
140      * Return the property name.
141      */
142     public String   getProperty() {
143 
144         return (this.property);
145 
146     }
147 
148 
149     /**
150      * Set the property name.
151      *
152      * @param property The new property name
153      */
154     public void setProperty(String   property) {
155 
156         this.property = property;
157 
158     }
159 
160 
161     /**
162      * Return the comparison value.
163      */
164     public String   getValue() {
165 
166         return (this.value);
167 
168     }
169 
170 
171     /**
172      * Set the comparison value.
173      *
174      * @param value The new comparison value
175      */
176     public void setValue(String   value) {
177 
178         this.value = value;
179 
180     }
181 
182 
183     // --------------------------------------------------------- Public Methods
184 
185 
186     /**
187      * Render the beginning of this select tag.
188      * <p>
189      * Support for indexed property since Struts 1.1
190      *
191      * @exception JspException if a JSP exception has occurred
192      */
193     public int doStartTag() throws JspException   {
194 
195         TagUtils.getInstance().write(pageContext, renderSelectStartElement());
196 
197         // Store this tag itself as a page attribute
198         pageContext.setAttribute(Constants.SELECT_KEY, this);
199 
200         this.calculateMatchValues();
201 
202         return (EVAL_BODY_TAG);
203     }
204 
205     /**
206      * Create an appropriate select start element based on our parameters.
207      * @throws JspException
208      * @since Struts 1.1
209      */
210     protected String   renderSelectStartElement() throws JspException   {
211         StringBuffer   results = new StringBuffer  ("<select");
212         
213         prepareAttribute(results, "name", prepareName());
214         prepareAttribute(results, "accesskey", getAccesskey());
215         if (multiple != null) {
216             results.append(" multiple=\"multiple\"");
217         }
218         prepareAttribute(results, "size", getSize());
219         prepareAttribute(results, "tabindex", getTabindex());
220         results.append(prepareEventHandlers());
221         results.append(prepareStyles());
222         prepareOtherAttributes(results);
223         results.append(">");
224         
225         return results.toString();
226     }
227 
228     /**
229      * Calculate the match values we will actually be using.
230      * @throws JspException
231      */
232     private void calculateMatchValues() throws JspException   {
233         if (this.value != null) {
234             this.match = new String  [1];
235             this.match[0] = this.value;
236             
237         } else {
238             Object   bean = TagUtils.getInstance().lookup(pageContext, name, null);
239             if (bean == null) {
240                 JspException   e =
241                     new JspException  (messages.getMessage("getter.bean", name));
242                     
243                 TagUtils.getInstance().saveException(pageContext, e);
244                 throw e;
245             }
246 
247             try {
248                 this.match = BeanUtils.getArrayProperty(bean, property);
249                 if (this.match == null) {
250                     this.match = new String  [0];
251                 }
252 
253             } catch (IllegalAccessException   e) {
254                 TagUtils.getInstance().saveException(pageContext, e);
255                 throw new JspException  (
256                     messages.getMessage("getter.access", property, name));
257 
258             } catch (InvocationTargetException   e) {
259                 Throwable   t = e.getTargetException();
260                 TagUtils.getInstance().saveException(pageContext, t);
261                 throw new JspException  (
262                     messages.getMessage("getter.result", property, t.toString()));
263 
264             } catch (NoSuchMethodException   e) {
265                 TagUtils.getInstance().saveException(pageContext, e);
266                 throw new JspException  (
267                     messages.getMessage("getter.method", property, name));
268             }
269         }
270     }
271 
272 
273     /**
274      * Save any body content of this tag, which will generally be the
275      * option(s) representing the values displayed to the user.
276      *
277      * @exception JspException if a JSP exception has occurred
278      */
279     public int doAfterBody() throws JspException   {
280 
281         if (bodyContent != null) {
282             String   value = bodyContent.getString();
283             if (value == null) {
284                 value = "";
285             }
286             
287             this.saveBody = value.trim();
288         }
289         
290         return (SKIP_BODY);
291     }
292 
293 
294     /**
295      * Render the end of this form.
296      *
297      * @exception JspException if a JSP exception has occurred
298      */
299     public int doEndTag() throws JspException   {
300 
301         // Remove the page scope attributes we created
302         pageContext.removeAttribute(Constants.SELECT_KEY);
303 
304         // Render a tag representing the end of our current form
305         StringBuffer   results = new StringBuffer  ();
306         if (saveBody != null) {
307             results.append(saveBody);
308             saveBody = null;
309         }
310         results.append("</select>");
311 
312         TagUtils.getInstance().write(pageContext, results.toString());
313 
314         return (EVAL_PAGE);
315     }
316 
317     /**
318      * Prepare the name element
319      * @return The element name.
320      */
321     protected String   prepareName() throws JspException   {
322 
323         if (property == null) {
324             return null;
325         }
326 
327         // * @since Struts 1.1
328         if(indexed) {
329             StringBuffer   results = new StringBuffer  ();
330             prepareIndex(results, name);
331             results.append(property);
332             return results.toString();
333         }
334 
335         return property;
336 
337     }
338 
339     /**
340      * Release any acquired resources.
341      */
342     public void release() {
343 
344         super.release();
345         match = null;
346         multiple = null;
347         name = Constants.BEAN_KEY;
348         property = null;
349         saveBody = null;
350         size = null;
351         value = null;
352 
353     }
354 
355 }
356
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags