messagestag.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

/*
 * $Header: /sfroot/cvs/esimple/src/core/com/esimple/framework/web/taglib/html/MessagesTag.java,v 1.1.1.1 2004/09/08 06:38:18 lava Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/09/08 06:38:18 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Struts", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.esimple.framework.web.taglib.html;

import java.util.Iterator;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.Globals;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionMessages;
import org.apache.struts.util.MessageResources;
import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.ResponseUtils;

/**
 * Custom tag that iterates the elements of a message collection.
 * It defaults to retrieving the messages from <code>Globals.ERROR_KEY</code>,
 * but if the message attribute is set to true then the messages will be
 * retrieved from <code>Globals.MESSAGE_KEY</code>. This is an alternative
 * to the default <code>ErrorsTag</code>.
 *
 * @author David Winterfeldt
 * @version $Revision: 1.1.1.1 $ $Date: 2004/09/08 06:38:18 $
 * @since Struts 1.1
 */
public class MessagesTag extends BodyTagSupport {

    /**
     * The message resources for this package.
     */
    protected static MessageResources messageResources =
       MessageResources.getMessageResources(Constants.Package + ".LocalStrings");

    /**
     * Commons Logging instance.
     */
    private static Log log = LogFactory.getLog(MessagesTag.class);

    /**
     * Iterator of the elements of this error collection, while we are actually
     * running.
     */
    protected Iterator iterator = null;

    /**
     * Whether or not any error messages have been processed.
     */
    protected boolean processed = false;

    /**
     * The name of the scripting variable to be exposed.
     */
    protected String id = null;

    /**
     * The servlet context attribute key for our resources.
     */
    protected String bundle = null;

    /**
     * The session attribute key for our locale.
     */
    protected String locale = Globals.LOCALE_KEY;

    /**
     * The request attribute key for our error messages (if any).
     */
    protected String name = Globals.ERROR_KEY;

    /**
     * The name of the property for which error messages should be returned,
     * or <code>null</code> to return all errors.
     */
    protected String property = null;

    /**
     * The message resource key for errors header.
     */
    protected String header = null;

    /**
     * The message resource key for errors footer.
     */
    protected String footer = null;

    /**
     * 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 String getId() {
        return (this.id);
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getBundle() {
        return (this.bundle);
    }

    public void setBundle(String bundle) {
        this.bundle = bundle;
    }

    public String getLocale() {
        return (this.locale);
    }

    public void setLocale(String locale) {
        this.locale = locale;
    }

    public String getName() {
        return (this.name);
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getProperty() {
        return (this.property);
    }

    public void setProperty(String property) {
        this.property = property;
    }

    public String getHeader() {
        return (this.header);
    }

    public void setHeader(String header) {
        this.header = header;
    }

    public String getFooter() {
        return (this.footer);
    }

    public void setFooter(String footer) {
        this.footer = footer;
    }

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

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

    /**
     * Construct an iterator for the specified collection, and begin
     * looping through the body once per element.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
        // Initialize for a new request.
        processed = false;

        // Were any messages specified?
        ActionMessages messages = null;

        // Make a local copy of the name attribute that we can modify.
        String name = this.name;

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

        try {
            messages = RequestUtils.getActionMessages(pageContext, name);
        } catch (JspException e) {
            RequestUtils.saveException(pageContext, e);
            throw e;
        }

        // Acquire the collection we are going to iterate over
        this.iterator = (property == null) ? messages.get() : messages.get(property);

        // Store the first value and evaluate, or skip the body if none
        if (!this.iterator.hasNext()) {
            return SKIP_BODY;
        }
        
        ActionMessage report = (ActionMessage) this.iterator.next();
        String msg =
            RequestUtils.message(
                pageContext,
                bundle,
                locale,
                report.getKey(),
                report.getValues());

        if (msg != null) {
            pageContext.setAttribute(id, msg);
        } else {
            pageContext.removeAttribute(id);

            // log missing key to ease debugging
            if (log.isDebugEnabled()) {
                log.debug(
                    messageResources.getMessage(
                        "messageTag.resources",
                        report.getKey()));
            }
        }

        if (header != null && header.length() > 0) {
            String headerMessage =
                RequestUtils.message(pageContext, bundle, locale, header);
                
            if (headerMessage != null) {
                ResponseUtils.write(pageContext, headerMessage);
            }
        }

        // Set the processed variable to true so the
        // doEndTag() knows processing took place
        processed = true;

        return (EVAL_BODY_TAG);
    }

    /**
     * Make the next collection element available and loop, or
     * finish the iterations if there are no more elements.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doAfterBody() throws JspException {
        // Render the output from this iteration to the output stream
        if (bodyContent != null) {
            ResponseUtils.writePrevious(pageContext, bodyContent.getString());
            bodyContent.clearBody();
        }

        // Decide whether to iterate or quit
        if (iterator.hasNext()) {
               ActionMessage report = (ActionMessage)iterator.next();
               String msg = RequestUtils.message(pageContext, bundle,
                                                 locale, report.getKey(),
                                                 report.getValues());

           pageContext.setAttribute(id, msg);

           return (EVAL_BODY_TAG);
        } else {
           return (SKIP_BODY);
        }

    }


    /**
     * Clean up after processing this enumeration.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doEndTag() throws JspException {
       if (processed && footer != null && footer.length() > 0) {
          String footerMessage = RequestUtils.message(pageContext, bundle,
                                                         locale, footer);
          if (footerMessage != null) {
             // Print the results to our output writer
             ResponseUtils.write(pageContext, footerMessage);
          }
       }
       // Continue processing this page
       return (EVAL_PAGE);
    }


    /**
     * Release all allocated resources.
     */
    public void release() {
       super.release();
       iterator = null;
       processed = false;
       id = null;
       bundle = null;
       locale = Globals.LOCALE_KEY;
       name = Globals.ERROR_KEY;
       property = null;
       header = null;
       footer = null;
       message = null;
    }

}