Source code: org/apache/taglibs/datetime/ErasTag.java

   /*
    * Copyright 1999,2004 The Apache Software Foundation.
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
    * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.taglibs.datetime;
  
  import java.util.*;
  import java.text.*;
  import javax.servlet.*;
  import javax.servlet.http.*;
  import javax.servlet.jsp.*;
  import javax.servlet.jsp.tagext.*;
  
  /**
   * JSP Tag <b>eras</b>, used to loop through all the era strings
   * so that they can be accessed by using the standard
   * JSP &lt;jsp:getProperty&gt; tag.
   * <p>
   * The script variable of name <b>id</b> is availble only within the
   * body of the <b>eras</b> tag.
   * <p>
   * Loops through all the era strings.
   * <p>
   * If the optional attribute <b>locale</b> is true, the strings
   * are formatted for the clients locale if known.
   * <p>                                                         
   * The optional attribute <b>localeRef</b> can be used to specify
   * the name of a page, session, application, or request scope attribute
   * of type java.util.Locale to use.
   * <p>
   * JSP Tag Lib Descriptor
   * <p><pre>
   * &lt;name&gt;eras&lt;/name&gt;
   * &lt;tagclass&gt;org.apache.taglibs.datetime.ErasTag&lt;/tagclass&gt;
   * &lt;teiclass&gt;org.apache.taglibs.datetime.ErasTEI&lt;/teiclass&gt;
   * &lt;bodycontent&gt;JSP&lt;/bodycontent&gt;
   * &lt;info&gt;Loop through all the era names.&lt;/info&gt;
   *   &lt;attribute&gt;
   *     &lt;name&gt;id&lt;/name&gt;
   *     &lt;required&gt;true&lt;/required&gt;
   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
   *   &lt;/attribute&gt;
   *   &lt;attribute&gt;
   *     &lt;name&gt;locale&lt;/name&gt;
   *     &lt;required&gt;false&lt;/required&gt;
   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
   *   &lt;/attribute&gt;
   *   &lt;attribute&gt;                             
   *     &lt;name&gt;localeRef&lt;/name&gt;
   *     &lt;required&gt;false&lt;/required&gt;
   *     &lt;rtexprvalue&gt;false&lt;/rtexprvalue&gt;
   *   &lt;/attribute&gt;
   * </pre>
   *
   * @author Glenn Nielsen
   */
  
  public class ErasTag extends BodyTagSupport
  {
      // Static constants                     
      private static String PATTERN = "yyyy";
  
      // eras tag attributes
      private boolean locale_flag = false;
      private String localeRef = null;
  
      // eras tag invocation variables
      private String [] eras = null;
      private int count = 0;
  
      /**
       * Initializes tag so it can loop through the eras of the year.
       *
       * @return EVAL_BODY_TAG
       */
      public final int doStartTag() throws JspException
      {
          // Initialize variables                      
          count = 0;
  
          SimpleDateFormat sdf;
          // Get a SimpleDateFormat using locale if necessary
          if( localeRef != null ) {                          
              Locale locale = (Locale)pageContext.findAttribute(localeRef);
              if( locale == null ) {                                       
                  throw new JspException(                                  
                      "datetime eras tag could not find locale for localeRef \"" +
                     localeRef + "\".");                                          
             }                                                                    
  
             sdf = new SimpleDateFormat(PATTERN,locale);
         } else if( locale_flag ) {
             sdf = new SimpleDateFormat(PATTERN,
                       (Locale)pageContext.getRequest().getLocale());
         } else {
             sdf = new SimpleDateFormat(PATTERN);
         }
 
   DateFormatSymbols dfs = sdf.getDateFormatSymbols();
   eras = dfs.getEras();
   // Make sure we skip any blank array elements
         while( count < eras.length && 
             (eras[count] == null || eras[count].length() == 0) )
                 count++;
         if( count >= eras.length )
             return SKIP_BODY;
 
         pageContext.setAttribute(id,this,PageContext.PAGE_SCOPE);
   return EVAL_BODY_TAG;
     }
 
     /**
      * Method called at end of each eras tag.
      *
      * @return EVAL_BODY_TAG if there is another era, or SKIP_BODY if there are no more eras
      */
     public final int doAfterBody() throws JspException
     {
   // See if we are done looping through eras
   count++;
         if( count >= eras.length )
             return SKIP_BODY;
   // Make sure we skip any blank array elements
         while( count < eras.length && 
       (eras[count] == null || eras[count].length() == 0) )
                 count++;
 
   if( count >= eras.length )
       return SKIP_BODY;
 
   // There is another era, so loop again
   return EVAL_BODY_TAG;
     }
 
     /**
      * Method called at end of Tag
      * @return EVAL_PAGE
      */
     public final int doEndTag() throws JspException
     {
         pageContext.removeAttribute(id,PageContext.PAGE_SCOPE);
   try
   {
       if(bodyContent != null)
       bodyContent.writeOut(bodyContent.getEnclosingWriter());
   } catch(java.io.IOException e)
   {
       throw new JspException("IO Error: " + e.getMessage());
   }
   return EVAL_PAGE;
     }
 
     /**
      * Locale flag, if set to true, use era names
      * for client's preferred locale if known.
      *
      * @param boolean either <b>true</b> or <b>false</b>
      */
     public final void setLocale(boolean flag)
     {
         locale_flag = flag;
     }
 
     /**
      * Provides a key to search the page context for in order to get the
      * java.util.Locale to use.
      *  
      * @param String name of locale attribute to use 
      */
     public void setLocaleRef(String value)
     {
         localeRef = value;
     }
 
     /**
      * Returns the era name.
      * <p>
      * &lt;jsp:getProperty name=<i>"id"</i> property="name"/&gt;
      *
      * @return String - era name
      */
     public final String getName()
     {  
         return eras[count];
     }
 
 }