altrowtag.java

一个实用工具类

/*
 * Copyright (C) butor.com. All rights reserved.
 *
 * This software is published under the terms of the GNU Library General
 * Public License (GNU LGPL), a copy of which has been included with this
 * distribution in the LICENSE.txt file. 
 */


package org.butor.web.taglib.html;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.Tag;
import javax.servlet.jsp.tagext.TagSupport;

import org.apache.struts.taglib.logic.IterateTag;

/**
 * This tag renders an HTML <TR> with alternating
 * style class.  This tag must be nested into an IterateTag.
 * 
 * @author 	mateusfi
 */
public class AltRowTag extends TagSupport {
	// Default values
	protected String f_evenStyleClass = "even";
	protected String f_oddStyleClass = "odd";
	
	/**
	 * Reference to the parent IterateTag.
	 */
	protected IterateTag f_iterateParent;
	
	/**
	 * @see Tag#doEndTag()
	 */
	public int doEndTag() throws JspException {
		if (f_iterateParent == null) {
			return EVAL_PAGE;
		}
		
		try {
			JspWriter jspWriter = pageContext.getOut();
			jspWriter.println("</tr>");
		} catch (IOException e) {
			throw new JspException(e);
		}
		
		return EVAL_PAGE;
	}

	/**
	 * @see Tag#doStartTag()
	 */
	public int doStartTag() throws JspException {
		if (f_iterateParent == null) {
			f_iterateParent = findParentIterateTag();
		}

		try {
			JspWriter jspWriter = pageContext.getOut();
			if (f_iterateParent != null) {
				jspWriter.print("<tr class=");
				
				int index = f_iterateParent.getIndex();
				
				if ((index % 2) == 0) {
					jspWriter.print("\"" + getEvenStyleClass() + "\"");
				} else {
					jspWriter.print("\"" + getOddStyleClass() + "\"");
				}
				jspWriter.print(">\n");		
			} else {
				jspWriter.print("Can't find parent IterateTag");
				return SKIP_BODY;
			}
		} catch (IOException e) {
			throw new JspException(e);
		}
	
		return EVAL_BODY_INCLUDE;
	}

	/**
	 * Browse through all the parent chain and try to find an IterateTag.
	 * 
	 * @return the IterateTag parent, or null if not found.
	 */
	protected IterateTag findParentIterateTag() {
		Tag parent = getParent();
		while (parent !=null && !(parent instanceof IterateTag)) {
			parent = parent.getParent();
		}
		
		return (IterateTag)parent;
	}

	public String getEvenStyleClass() {
		return f_evenStyleClass;
	}
	public void setEvenStyleClass(String evenStyleClass) {
		f_evenStyleClass = evenStyleClass;
	}

	public String getOddStyleClass() {
		return f_oddStyleClass;
	}
	public void setOddStyleClass(String oddStyleClass) {
		f_oddStyleClass = oddStyleClass;
	}
	/**
	 * @see Tag#release()
	 */
	public void release() {
		f_iterateParent = null;
		f_evenStyleClass = null;
		f_oddStyleClass = null;
	}
}