iteratortag.java

webwork source

/*
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.view.taglib;

import org.apache.commons.logging.*;
import webwork.util.MakeIterator;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import java.util.*;
import java.lang.reflect.Array;

/**
 * Tag to iterate over an iterable value.
 *
 * An iterable value can be either of: java.util.Collection, java.util.Iterator,
 * java.util.Enumeration, java.util.Map, array, XML Node, or XML NodeList
 *
 * @author Rickard 謆erg ([e-mail])
 * @version $Revision: 1.9 $
 */
public class IteratorTag
   extends WebWorkBodyTagSupport
{
   // Attributes ----------------------------------------------------
   protected String valueAttr;
   protected String statusAttr;
   protected Object currentValue;
   protected Iterator iterator;
   protected IteratorStatus status;
   protected IteratorStatus.StatusState statusState;
   protected String statusName;
   protected Object oldStatus;

   // Public --------------------------------------------------------

   /**
    * Set the name of the property whose value is iterable.
    *
    * @param   aName
    */
   public void setValue(String aName)
   {
      valueAttr = aName;
   }

   /**
    * Set the name of the status object that is to be exposed.
    *
    * @param   aName
    */
   public void setStatus(String aName)
   {
      statusAttr = aName;
   }

   // BodyTag implementation ----------------------------------------
   public int doStartTag()
   {
      if (statusAttr != null)
      {
         statusState = new IteratorStatus.StatusState();
         status = new IteratorStatus(statusState);
      }

      Object value = findValue(valueAttr);

      if(value != null)
      {
         // Make sure it is iterable
         iterator = MakeIterator.convert(value);
         
         // Get first item
         if(iterator.hasNext())
         {
            currentValue = iterator.next();
            getStack().pushValue(currentValue);

            String id = getId();
            if(id != null && currentValue != null)
            {
               pageContext.setAttribute(id, currentValue);
               pageContext.setAttribute(id, currentValue, PageContext.REQUEST_SCOPE);
            }

            // Status object
            if (statusAttr != null)
            {
               statusState.setLast(!iterator.hasNext());
               statusName = (String)findValue(statusAttr);
               oldStatus = pageContext.getAttribute(statusName);
               pageContext.setAttribute(statusName, status);
            }

            return EVAL_BODY_TAG;
         }
         else
         {
            return SKIP_BODY;
         }
      }  else {
         LogFactory.getLog(IteratorTag.class.getName()).warn("Value is null! Returning an empty set.");
         return SKIP_BODY;
      }
   }

   public int doAfterBody()
      throws JspException
   {
      getStack().popValue();

      if(iterator.hasNext())
      {
         currentValue = iterator.next();

         // Update status
         if (status != null)
         {
            statusState.next(); // Increase counter
            statusState.setLast(!iterator.hasNext());
         }

         getStack().pushValue(currentValue);
         String id = getId();
         if(id != null && currentValue != null)
         {
            pageContext.setAttribute(getId(), currentValue);
            pageContext.setAttribute(getId(), currentValue, PageContext.REQUEST_SCOPE);
         }
         return EVAL_BODY_TAG;
      }
      else
      {
         // Reset status object (if someone else has set one with same name)
         if (status != null)
         {
            if (oldStatus == null)
               pageContext.removeAttribute(statusName);
            else
               pageContext.setAttribute(statusName, oldStatus);
         }

         // Release objects
         currentValue = null;
         iterator = null;
         status = null;

         // Write result
         try
         {
            bodyContent.writeOut(bodyContent.getEnclosingWriter());
         } catch (Exception e)
         {
            throw new JspException(e.getMessage());
         }

         return SKIP_BODY;
      }
   }
}