FormatTag


1   /*
2    * Copyright 1999,2004 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.taglibs.datetime;
18  
19  import java.util.*;
20  import java.text.*;
21  import javax.servlet.*;
22  import javax.servlet.http.*;
23  import javax.servlet.jsp.*;
24  import javax.servlet.jsp.tagext.*;
25  
26  /**
27   * JSP Tag <b>format</b>, used to format a Date for display.
28   * <p>
29   * The Date as a long in milliseconds is obtained from the body of the tag.
30   * <p>
31   * Uses the optional attribute <b>pattern</b> as the time pattern
32   * string to use when formatting the Date.
33   * <p>
34   * The optional attribute <b>timeZone</b> can be set to the id of
35   * a timeZone script varaible so that the Date if adjusted for 
36   * that timeZone.
37   * <p>
38   * If the optional attribute <b>locale</b> is true, the Date
39   * is formatted for the clients locale if known.
40   * <p>
41   * The optional attribute <b>date</b> can be set to a
42   * Date object using a runtime expression value.  If set,
43   * date will be used instead of the tag body.
44   * <p>
45   * The optional attribute <b>default</b> can be set to a
46   * default string to output if the date object doesn't exist
47   * or the tag body is not a valid date.  If no default is set,
48   * the string "Invalid Date" is output.
49   * <p>
50   * The optional attribute <b>localeRef</b> can be used to specify
51   * the name of a page, session, application, or request scope attribute
52   * of type java.util.Locale to use.
53   * <p>
54   * JSP Tag Lib Descriptor
55   * <p><pre>
56   * &lt;name&gt;format&lt;/name&gt;
57   * &lt;tagclass&gt;org.apache.taglibs.datetime.FormatTag&lt;/tagclass&gt;
58   * &lt;bodycontent&gt;JSP&lt;/bodycontent&gt;
59   * &lt;info&gt;Formats a date for output.&lt;/info&gt;
60   *   &lt;attribute&gt;
61   *     &lt;name&gt;pattern&lt;/name&gt;
62   *     &lt;required&gt;false&lt;/required&gt;
63   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
64   *   &lt;/attribute&gt;
65   *   &lt;attribute&gt;
66   *     &lt;name&gt;patternId&lt;/name&gt;
67   *     &lt;required&gt;false&lt;/required&gt;
68   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
69   *   &lt;/attribute&gt;
70   *   &lt;attribute&gt;
71   *     &lt;name&gt;timeZone&lt;/name&gt;
72   *     &lt;required&gt;false&lt;/required&gt;
73   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
74   *   &lt;/attribute&gt;
75   *   &lt;attribute&gt;
76   *     &lt;name&gt;locale&lt;/name&gt;
77   *     &lt;required&gt;false&lt;/required&gt;
78   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
79   *   &lt;/attribute&gt;
80   *   &lt;attribute&gt;
81   *     &lt;name&gt;date&lt;/name&gt;
82   *     &lt;required&gt;false&lt;/required&gt;
83   *     &lt;rtexprvalue&gt;true&lt;/rtexprvalue&gt;
84   *   &lt;/attribute&gt;
85   *   &lt;attribute&gt;
86   *     &lt;name&gt;default&lt;/name&gt;
87   *     &lt;required&gt;false&lt;/required&gt;
88   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
89   *   &lt;/attribute&gt;
90   *   &lt;attribute&gt;
91   *     &lt;name&gt;localeRef&lt;/name&gt;
92   *     &lt;required&gt;false&lt;/required&gt;
93   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
94   *   &lt;/attribute&gt;
95   *   &lt;attribute&gt;
96   *     &lt;name&gt;symbolsRef&lt;/name&gt;
97   *     &lt;required&gt;false&lt;/required&gt;
98   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
99   *   &lt;/attribute&gt;
100  * </pre>
101  *
102  * @author Glenn Nielsen
103  * @author Mark Femal
104  */
105 
106 public class FormatTag extends BodyTagSupport
107 {
108 
109     // format tag attributes
110 
111     // Optional attribute, use users locale if known when formatting date
112     private boolean locale_flag = false;
113     // Optional attribute, time pattern string to use when formatting date
114     private String   pattern = null;
115     // Optional attribute, name of script variable to use as pattern
116     private String   patternid = null;
117     // Optional attribute, timeZone script variable id to use when formatting date
118     private String   timeZone_string;
119     // Optional attribute, date object from rtexprvalue
120     private Date date = null;
121     // Optional attribute, the default text if the tag body or date given is invalid/null
122     private String   default_text = "Invalid Date";
123     // Optional attribute, the name of an attribute which contains the Locale
124     private String   localeRef = null;
125     // Optional attribute, name of script variable to use as date symbols source
126     private String   symbolsRef = null;
127 
128     // format tag invocation variables
129 
130     // The symbols object
131     private DateFormatSymbols symbols = null;
132     // The date to be formatted an output by tag
133     private Date output_date = null;
134 
135     /**
136      * Method called at start of tag, always returns EVAL_BODY_TAG
137      *
138      * @return EVAL_BODY_TAG
139      */
140     public final int doStartTag() throws JspException
141     {
142         output_date = date;
143         return EVAL_BODY_TAG;
144     }
145 
146     /**
147      * Method called at end of format tag body.
148      *
149      * @return SKIP_BODY
150      */
151     public final int doAfterBody() throws JspException
152     {
153         // Use the body of the tag as input for the date
154         BodyContent body = getBodyContent();
155         String   s = body.getString().trim();  
156         // Clear the body since we will output only the formatted date
157         body.clearBody();
158         if( output_date == null ) {
159             long time;
160             try {
161                 time = Long.valueOf(s).longValue();
162                 output_date = new Date(time);
163             } catch(NumberFormatException   nfe) {
164             }
165         }
166 
167         return SKIP_BODY;
168     }
169 
170     /**
171      * Method called at end of Tag
172      *
173      * @return EVAL_PAGE
174      */
175     public final int doEndTag() throws JspException
176     {
177         String   date_formatted = default_text;
178 
179         if (output_date != null) {
180             // Get the pattern to use
181             SimpleDateFormat sdf;
182             String   pat = pattern;
183 
184             if (pat == null && patternid != null) {
185                 Object   attr = pageContext.findAttribute(patternid);
186                 if (attr != null)
187                     pat = attr.toString();
188             }
189 
190             if (pat == null) {
191                 sdf = new SimpleDateFormat();
192                 pat = sdf.toPattern();
193             }
194 
195             // Get a DateFormatSymbols
196             if (symbolsRef != null) {
197                 symbols = (DateFormatSymbols) pageContext.findAttribute(symbolsRef);
198                 if (symbols == null) {
199                     throw new JspException(
200                             "datetime format tag could not find dateFormatSymbols for symbolsRef \"" +
201                             symbolsRef + "\".");
202                 }
203             }
204 
205             // Get a SimpleDateFormat using locale if necessary
206             if (localeRef != null) {
207                 Locale locale = (Locale) pageContext.findAttribute(localeRef);
208                 if (locale == null) {
209                     throw new JspException(
210                             "datetime format tag could not find locale for localeRef \"" +
211                             localeRef + "\".");
212                 }
213 
214                 sdf = new SimpleDateFormat(pat, locale);
215             } else if (locale_flag) {
216                 sdf = new SimpleDateFormat(pat,
217                         (Locale) pageContext.getRequest().getLocale());
218             } else if (symbols != null) {
219                 sdf = new SimpleDateFormat(pat,
220                         symbols);
221             } else {
222                 sdf = new SimpleDateFormat(pat);
223             }
224 
225             // See if there is a timeZone
226             if (timeZone_string != null) {
227                 TimeZone timeZone =
228                         (TimeZone) pageContext.getAttribute(timeZone_string,
229                                 PageContext.SESSION_SCOPE);
230                 if (timeZone == null) {
231                     throw new JspTagException("Datetime format tag timeZone " +
232                             "script variable \"" + timeZone_string +
233                             " \" does not exist");
234                 }
235                 sdf.setTimeZone(timeZone);
236             }
237 
238             // Format the date for display
239             date_formatted = sdf.format(output_date);
240         }
241 
242         try {
243             pageContext.getOut().write(date_formatted);
244         } catch (Exception   e) {
245             throw new JspException("IO Error: " + e.getMessage());
246         }
247 
248         return EVAL_PAGE;
249     }
250 
251     public void release()
252     {
253         super.release();
254         locale_flag = false;
255         pattern = null;
256         patternid = null;
257         date = null;
258         localeRef = null;
259         symbolsRef = null;
260         symbols = null;
261     }
262 
263     /**
264      * Locale flag, if set to true, format date
265      * for client's preferred locale if known.
266      *
267      * @param boolean use users locale, true or false
268      */
269     public final void setLocale(boolean flag)
270     {
271         locale_flag = flag;
272     }
273 
274     /**
275      * Set the time zone to use when formatting date.
276      *
277      * Value must be the name of a <b>timeZone</b> tag script
278      * variable ID.
279      *
280      * @param String name of timeZone to use
281      */
282     public final void setTimeZone(String   tz)
283     {
284         timeZone_string = tz;
285     }
286 
287     /**
288      * Set the pattern to use when formatting Date.
289      *
290      * @param String SimpleDateFormat style time pattern format string
291      */
292     public final void setPattern(String   str)
293     {
294         pattern = str;
295     }
296 
297     /**
298      * Set the pattern to use when parsing Date using a script variable
299      * attribute.
300      * 
301      * @param String name of script variable attribute id
302      */
303     public final void setPatternId(String   str)
304     {   
305         patternid = str;
306     }
307 
308     /**
309      * Set the date to use (overrides tag body) for formatting
310      *
311      * @param Date to use for formatting (could be null)
312      */
313     public final void setDate(Date date)
314     {
315         this.date = date;
316     }
317 
318     /**
319      * Set the default text if an invalid date or no tag body is given
320      *
321      * @param String to use as default text
322      */
323     public final void setDefault(String   default_text)
324     {
325         this.default_text = default_text;
326     }
327 
328     /**
329      * Provides a key to search the page context for in order to get the
330      * java.util.Locale to use.
331      *
332      * @param String name of locale attribute to use
333      */
334     public void setLocaleRef(String   value)
335     {
336         localeRef = value;
337     }
338 
339     /**
340      * Provides a key to search the page context for in order to get the
341      * java.text.DateFormatSymbols to use
342      *
343      * @param symbolsRef
344      */
345     public void setSymbolsRef(String   symbolsRef) throws JspException
346     {
347         this.symbolsRef = symbolsRef;
348     }
349 }
350
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