messagespresenttag.java

这是一个轻便的j2ee的web应用框架,是一个在多个项目中运用的实际框架,采用struts,hebinate,xml等技术,有丰富的tag,role,navigation,session,dictio

/*
 * The Apache Software License, Version 1.1
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 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
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 *    if and wherever such third-party acknowlegements normally appear.
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package com.esimple.framework.web.taglib.logic;

import java.util.Iterator;

import javax.servlet.jsp.JspException;

import org.apache.struts.Globals;
import org.apache.struts.action.ActionMessages;
import org.apache.struts.util.RequestUtils;


/**
 * Evalute to <code>true</code> if an <code>ActionMessages</code> class or a
 * class that can be converted to an <code>ActionMessages</code> class is in
 * request scope under the specified key and there is at least one message in the
 * class or for the property specified.
 *
 * @author David Winterfeldt
 * @version $Revision: 1.1.1.1 $ $Date: 2004/09/08 06:38:21 $
 * @since Struts 1.1
 */

public class MessagesPresentTag extends ConditionalTagBase {

    /**
     * If this is set to 'true', then the <code>Globals.MESSAGE_KEY</code> will
     * be used to retrieve the messages from scope.
    */
    protected String message = null;


    public MessagesPresentTag() {
        name = Globals.ERROR_KEY;
    }

    public String getMessage() {
        return (this.message);
    }

    public void setMessage(String message) {
        this.message = message;
    }

    /**
     * Evaluate the condition that is being tested by this particular tag,
     * and return <code>true</code> if the nested body content of this tag
     * should be evaluated, or <code>false</code> if it should be skipped.
     * This method must be implemented by concrete subclasses.
     *
     * @exception JspException if a JSP exception occurs
     */
    protected boolean condition() throws JspException {

        return (condition(true));

    }


    /**
     * Evaluate the condition that is being tested by this particular tag,
     * and return <code>true</code> if there is at least one message in the
     * class or for the property specified.
     * This method must be implemented by concrete subclasses.
     *
     * @param desired Desired outcome for a true result
     *
     * @exception JspException if a JSP exception occurs
     */
    protected boolean condition(boolean desired) throws JspException {
        ActionMessages am = null;

        if (message != null && "true".equalsIgnoreCase(message))
           name = Globals.MESSAGE_KEY;

        // Evaluate the presence of the specified value
        boolean bMessages = false;

        try {
            // Definitely know it should be an error so
            // use method to retrieve errors.
            if (Globals.ERROR_KEY.equals(name)) {
                am = RequestUtils.getActionErrors(pageContext, name);
            } else {
                am = RequestUtils.getActionMessages(pageContext, name);
            }
        } catch (JspException e) {
            RequestUtils.saveException(pageContext, e);
            throw e;
        }

        Iterator iterator = null;

        if (property == null)
            iterator = am.get();
        else
            iterator = am.get(property);

        if (iterator.hasNext())
           bMessages = true;

        return (bMessages == desired);

    }

    /**
     * Release all allocated resources.
     */
    public void release() {
        super.release();
        name = Globals.ERROR_KEY;
        message = null;
    }

}