edu.cornell.mannlib.vitro.webapp.beans.DisplayMessage.java Source code

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Here is the source code for edu.cornell.mannlib.vitro.webapp.beans.DisplayMessage.java

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/* $This file is distributed under the terms of the license in /doc/license.txt$ */

package edu.cornell.mannlib.vitro.webapp.beans;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Store a message in the session, so it can be displayed on the page. Getting
 * the message also removes it from the session, so the same message is not
 * displayed repeatedly.
 */
public class DisplayMessage {
    private static final Log log = LogFactory.getLog(DisplayMessage.class);

    /** If there is no message, return this instead. */
    private static final String NO_MESSAGE = "";

    private static final String ATTRIBUTE_NAME = DisplayMessage.class.getName();

    /**
     * Store this message on the session. This will overwrite any previously
     * stored message.
     */
    public static void setMessage(HttpServletRequest request, String message) {
        setMessage(request.getSession(), message);
    }

    /**
     * Store this message on the session. This will overwrite any previously
     * stored message.
     */
    public static void setMessage(HttpSession session, String message) {
        session.setAttribute(ATTRIBUTE_NAME, message);
        log.debug("Set message: '" + message + "'");
    }

    /**
     * Get the current message from the session, and remove it from the session
     * so it won't be displayed again.
     * 
     * If there is no message, return the empty string.
     */
    public static String getMessageAndClear(HttpServletRequest request) {
        if (request == null) {
            return NO_MESSAGE;
        } else {
            return getMessageAndClear(request.getSession(false));
        }
    }

    /**
     * Get the current message from the session, and remove it from the session
     * so it won't be displayed again.
     * 
     * If there is no message, return the empty string.
     */
    public static String getMessageAndClear(HttpSession session) {
        String message = NO_MESSAGE;
        if (session != null) {
            Object sessionMessage = session.getAttribute(ATTRIBUTE_NAME);
            if (sessionMessage != null) {
                if (sessionMessage instanceof String) {
                    log.debug("Get message: '" + sessionMessage + "'");
                    message = (String) sessionMessage;
                }
                session.removeAttribute(ATTRIBUTE_NAME);
            } else {
                log.debug("Get no message.");
            }
        }
        return message;
    }
}