ParseTag


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>parse</b>, used to parse a Date string and output
28   * the time in ms.
29   * <p>
30   * The Date as a string is obtained from the body of the tag.
31   * <p>
32   * Uses the optional attribute <b>pattern</b> as the pattern
33   * to use when parsing the Date string.
34   * <p>
35   * The optional attribute <b>timeZone</b> can be set to the id of
36   * a timeZone script varaible so that the Date if adjusted for
37   * that timeZone.
38   * <p>
39   * If the optional attribute <b>locale</b> is true, the Date
40   * is parsed for the clients locale if known.
41   * <p>                                                        
42   * The optional attribute <b>localeRef</b> can be used to specify
43   * the name of a page, session, application, or request scope attribute
44   * of type java.util.Locale to use.
45   * <p>
46   * If the date string can not be parsed, 0 is returned.
47   * <p>
48   * JSP Tag Lib Descriptor
49   * <p><pre>
50   * &lt;name&gt;parse&lt;/name&gt;
51   * &lt;tagclass&gt;org.apache.taglibs.datetime.ParseTag&lt;/tagclass&gt;
52   * &lt;bodycontent&gt;JSP&lt;/bodycontent&gt;
53   * &lt;info&gt;Parses a date string and outputs the time in milliseconds since Jan 1, 1970 GMT.&lt;/info&gt;
54   *   &lt;attribute&gt;
55   *     &lt;name&gt;pattern&lt;/name&gt;
56   *     &lt;required&gt;false&lt;/required&gt;
57   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
58   *   &lt;/attribute&gt;
59   *   &lt;attribute&gt;
60   *     &lt;name&gt;patternId&lt;/name&gt;
61   *     &lt;required&gt;false&lt;/required&gt;
62   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
63   *   &lt;/attribute&gt;
64   *   &lt;attribute&gt;
65   *     &lt;name&gt;timeZone&lt;/name&gt;
66   *     &lt;required&gt;false&lt;/required&gt;
67   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
68   *   &lt;/attribute&gt;
69   *   &lt;attribute&gt;
70   *     &lt;name&gt;locale&lt;/name&gt;
71   *     &lt;required&gt;false&lt;/required&gt;
72   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
73   *   &lt;/attribute&gt;
74   *   &lt;attribute&gt;                             
75   *     &lt;name&gt;localeRef&lt;/name&gt;
76   *     &lt;required&gt;false&lt;/required&gt;
77   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
78   *   &lt;/attribute&gt;
79   * </pre>
80   *
81   * @author Glenn Nielsen
82   */
83  
84  public class ParseTag extends BodyTagSupport
85  {
86      // Optional attribute, use users locale if known when formatting date
87      private boolean locale_flag = false;
88      // Optional attribute, time pattern string to use when formatting date
89      private String   pattern = null;
90      // Optional attribute, name of script variable to use as pattern
91      private String   patternid = null;
92      // Optional attribute, timeZone script variable id to use when
93      // formatting date
94      private String   timeZone_string;
95      // Optional attribute, the name of an attribute which contains the Locale            
96      private String   localeRef = null;                                         
97                                                                               
98      // format tag invocation variables
99      private TimeZone timeZone = null;
100     // Date after parsing tag body
101     private Date date = null;
102 
103     /**
104      * Method called at start of tag, always returns EVAL_BODY_TAG
105      *
106      * @return EVAL_BODY_TAG
107      */
108     public final int doStartTag() throws JspException
109     {
110     return EVAL_BODY_TAG;
111     }
112 
113     /**
114      * Method called at end of parse tag body.
115      *
116      * @return SKIP_BODY
117      */
118     public final int doAfterBody() throws JspException
119     {
120     // Use the body of the tag as input for the date
121     BodyContent body = getBodyContent();
122     String   s = body.getString().trim();  
123     // Clear the body since we will output only the parseted date
124     body.clearBody();
125 
126         // Get the pattern to use
127         SimpleDateFormat sdf;    
128         String   pat = pattern; 
129  
130         if( pat == null && patternid != null ) {
131           Object   attr = pageContext.findAttribute(patternid);
132           if( attr != null )    
133             pat = attr.toString();
134         }
135         
136         if( pat == null ) {
137             sdf = new SimpleDateFormat(); 
138             pat = sdf.toPattern();
139         }
140 
141     // Get a SimpleDateFormat using locale if necessary
142         if( localeRef != null ) {                          
143             Locale locale = (Locale)pageContext.findAttribute(localeRef);
144             if( locale == null ) {                                       
145                 throw new JspException(                                  
146                     "datetime parse tag could not find locale for localeRef \"" +
147                     localeRef + "\".");                                           
148             }                                                                     
149                                        
150             sdf = new SimpleDateFormat(pat,locale);
151         } else if( locale_flag ) {                 
152             sdf = new SimpleDateFormat(pat,        
153                       (Locale)pageContext.getRequest().getLocale());
154         } else {                                                    
155             sdf = new SimpleDateFormat(pat);                        
156         }
157 
158     // See if there is a timeZone
159         if( timeZone_string != null ) {
160             timeZone =
161                 (TimeZone)pageContext.getAttribute(timeZone_string,
162                                                    PageContext.SESSION_SCOPE);
163         if( timeZone == null )
164                 throw new JspTagException("Datetime parse tag timeZone " +
165                     "script variable \"" + timeZone_string +
166                     " \" does not exist");
167             sdf.setTimeZone(timeZone);
168         }
169 
170     // Parse the string and create the date.
171     try {
172             date = null;
173         date = sdf.parse(s);
174     } catch(ParseException e) {
175     }
176     return SKIP_BODY;
177     }
178 
179     /**
180      * Method called at end of Tag
181      *
182      * @return EVAL_PAGE
183      */
184     public final int doEndTag() throws JspException
185     {
186     long time = 0;
187     if( date != null )
188         time = date.getTime();
189     try {
190         pageContext.getOut().write("" + time);
191     } catch(Exception   e) {
192         throw new JspException("IO Error: " + e.getMessage());
193     }
194 
195     return EVAL_PAGE;
196     }
197 
198     /**
199      * Locale flag, if set to true, date format is for
200      * client's preferred locale if known.
201      *
202      * @param boolean use users locale, true or false
203      */
204     public final void setLocale(boolean flag)
205     {
206         locale_flag = flag;
207     }
208  
209     /**
210      * Set the time zone to use when parsing date.
211      *
212      * Value must be the name of a <b>timeZone</b> tag script
213      * variable ID.
214      *
215      * @param String name of timeZone to use
216      */
217     public final void setTimeZone(String   tz)
218     { 
219         timeZone_string = tz;
220     } 
221  
222     /**   
223      * Set the pattern to use when parsing Date.
224      *
225      * @param String SimpleDateFormat style time pattern format string
226      */
227     public final void setPattern(String   str)
228     { 
229         pattern = str;
230     }
231 
232     /**
233      * Set the pattern to use when parsing Date using a script variable
234      * attribute.
235      *
236      * @param String name of script variable attribute id
237      */
238     public final void setPatternId(String   str)
239     {
240         patternid = str;
241     }
242 
243     /**
244      * Provides a key to search the page context for in order to get the
245      * java.util.Locale to use.
246      *
247      * @param String name of locale attribute to use
248      */
249     public void setLocaleRef(String   value)
250     {
251         localeRef = value;
252     }
253 
254 }
255
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags