arbitraryiteratorbodytag.java

基于struts框架的web开发应用实例

/**
 *
 * $Header: /raid1/wide/cvsroot/wide/dev/struts/struts-metadata/templates/new-app/nitroX-tour/site/WEB-INF/src/java/com/hp/mw/samples/struts/storefront/taglibs/ArbitraryIteratorBodyTag.java,v 1.1 2005/10/10 20:12:04 sami Exp $
 *
 * Copyright (c) 2002 by M7 Corporation
 * All rights reserved.
 *
 * The information contained herein is confidential and proprietary
 * to M7 Corporation, and considered a trade secret as defined under
 * civil and criminal statutes.  M7 Corporation shall pursue its
 * civil and criminal remedies in the event of unauthorized use or
 * misappropriation of its trade secrets.  Use of this information
 * by anyone other than authorized employees of M7 Corporation is
 * granted only under a written non-disclosure agreement, expressly
 * prescribing the scope and manner of such use.
 *
 */
package com.hp.mw.samples.struts.storefront.taglibs;

import java.util.*;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;


/**
 *
 * @author <a href="mailto:[e-mail]">Zaitrarrio Collier</a>
 * @version $ Revision: $
 */
public abstract class ArbitraryIteratorBodyTag
    extends AbstractBodyTag
{
    //~ Instance fields --------------------------------------------------------

    protected String   id;
    protected String   indexId;
    protected Iterator iterator = null;
    protected String   emptyText = "";
    protected int      index = 0;
    protected Object   currentObject;

    //~ Methods ----------------------------------------------------------------

    /**
     * Set's the id of the scripting variable that should contain the current object during iteration
     *
     * @param the id of the scripting variable that should contain the current object during iteration
     */
    public void setId( String value )
    {
        this.id = value;
    }

    /**
     * Set's the id of the scripting variable that should be used to contain the current index during iteration
     *
     * @param the id of the scripting variable that should be used to contain the current index during iteration
     */
    public void setIndexId( String value )
    {
        this.indexId = value;
    }

    public void setEmptyText( String value )
    {
        this.emptyText = value;
    }

    protected abstract Iterator getIterator(  )
        throws Exception;

    protected Object getCurrentObject(  )
    {
        return currentObject;
    }

    /**
     * Sets the attributes which are output to the jsp page
     */
    protected Object setOutputAttributes(  )
    {
        if ( id != null )
        {
            pageContext.setAttribute( id, currentObject = iterator.next(  ), PageContext.PAGE_SCOPE );
        }

        if ( indexId != null )
        {
            pageContext.setAttribute( indexId, new Integer( index++ ), PageContext.PAGE_SCOPE );
        }

        return currentObject;
    }

    /**
     * @see javax.servlet.jsp.tagext.BodyTag
     */
    public int doStartTag(  )
        throws JspException
    {
        try
        {
            // get the objects
            iterator = getIterator(  );
            if ( ( iterator == null ) || !iterator.hasNext(  ) )
            {
                JspWriter out = pageContext.getOut(  );

                out.print( emptyText );
                return ( SKIP_BODY );
            }

            // evaluate the body
            return ( EVAL_BODY_BUFFERED );
        }
        catch ( Exception e )
        {
            handlePageException( e );
            return ( SKIP_BODY );
        }
    }

    /**
     * @see javax.servlet.jsp.tagext.BodyTag
     */
    public void doInitBody(  )
    {
        setOutputAttributes(  );
    }

    /**
     * @see javax.servlet.jsp.tagext.BodyTag
     */
    public int doAfterBody(  )
        throws JspException
    {
        try
        {
            if ( iterator.hasNext(  ) )
            {
                setOutputAttributes(  );
                return EVAL_BODY_BUFFERED;
            }
            else
            {
                BodyContent body = getBodyContent(  );
                body.writeOut( getPreviousOut(  ) );
            }
        }
        catch ( Exception e )
        {
            handlePageException( e );
        }

        return ( SKIP_BODY );
    }
}