checkboxtag.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.jsp.JspException;

import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.ResponseUtils;
import org.butor.web.action.IButorActionForm;


/**
 * @author nacroaz
 *
 * To change this generated comment edit the template variable "typecomment":
 * Window>Preferences>Java>Templates.
 */
public class CheckboxTag extends org.apache.struts.taglib.html.CheckboxTag {
    /**
     * Generate the required input tag.
     * Indexed property since 1.1
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
	   	// Find and check the form bean	  
    	Object o = RequestUtils.lookup(pageContext, name, null);    	
        if (! (o instanceof IButorActionForm)) {
			ResponseUtils.write(pageContext, "The form bean must be an instance of ButorActionForm !!!");  
			return SKIP_BODY;
        }        
        IButorActionForm form = (IButorActionForm) o;
        
        // If property is enable, use super class definition 
        if (form.getEnabled(property)) {
        	return super.doStartTag();
        } else {        
        	// the property is disable, we must render it properly         	        	
	        // Acquire the current value of the appropriate field
    	    Object result = RequestUtils.lookup(pageContext, name,
                                            property, null);
			String propValue = null;
	        if (result == null) {
				propValue = "";
	        } else if (result instanceof String) {
				propValue = (String) result;
		    } else {
				propValue = result.toString();
		    }

			// if the property value is equal to the checkbox value
			// then it is on.
    	    if (propValue.equalsIgnoreCase(value)) {
				//  Add the checked image
				TagLibHelper.renderText(pageContext, "<img src=\"/_images/check_on.gif\">", false);
	            
				// Add an hidden field for this property
				TagLibHelper.renderHiddenField(pageContext, property, propValue);	
    	    } else {
				//  Add the checked image
				TagLibHelper.renderText(pageContext, "<img src=\"/_images/check_off.gif\">", false);
    	    }
        }    
        
        this.text = null;
    	return EVAL_BODY_BUFFERED;
    }	    
}