formtag.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 javax.servlet.ServletRequest;
import javax.servlet.jsp.JspException;

/**
 * @author nacroaz
 *
 * To change this generated comment edit the template variable "typecomment":
 * Window>Preferences>Java>Templates.
 */
public class FormTag extends org.apache.struts.taglib.html.FormTag {
	public static final String FIRST_FORM_TAG = "first_form_tag";
	
	protected boolean f_isFirstFormTag = false;
	
	public FormTag getFirstFormTag() {
		ServletRequest request = pageContext.getRequest();
		return (FormTag) request.getAttribute(FIRST_FORM_TAG);
	}
	
	protected FormTag setFirstFormTag(FormTag tag) {
		ServletRequest request = pageContext.getRequest();		
		FormTag oldFormTag = (FormTag) request.getAttribute(FIRST_FORM_TAG);
		
		if (tag != null) {
			request.setAttribute(FIRST_FORM_TAG, tag);	
		} else {
			request.removeAttribute(FIRST_FORM_TAG);
		}
		
		return oldFormTag;
	}	

	public int doStartTag() throws JspException {		
		FormTag formTag = getFirstFormTag();

		if (formTag == null) {
			f_isFirstFormTag = true;
			setFirstFormTag(this);
			return super.doStartTag();
		}			

		return EVAL_BODY_INCLUDE;
	}

	/**
	 * Render the end of this form.
	 *
	 * @exception JspException if a JSP exception has occurred
	 */
	public int doEndTag() throws JspException {
		if (f_isFirstFormTag) {
			setFirstFormTag(null);
			return super.doEndTag();	
		}	
		
		return EVAL_PAGE;
	}
}