lookupdispatchaction.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/org/apache/struts/actions/LookupDispatchAction.java,v 1.1.1.1 2004/09/08 06:38:32 lava Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/09/08 06:38:32 $
 * 
 *  ====================================================================
 *
 *  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
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 *  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
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 */
package org.apache.struts.actions;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.Globals;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.config.MessageResourcesConfig;
import org.apache.struts.config.ModuleConfig;
import org.apache.struts.util.MessageResources;

/**
 *  <p>
 *
 *  An abstract <strong>Action</strong> that dispatches to the subclass mapped
 *  <code>execute</code> method. This is useful in
 *  cases where an HTML form has multiple submit buttons with the same name. The
 *  button name is specified by the <code>parameter</code> property of the
 *  corresponding ActionMapping. To configure the use of this action in your
 *  <code>struts-config.xml</code> file, create an entry like this:</p> <pre>
 *   &lt;action path="/test"
 *           type="org.example.MyAction"
 *           name="MyForm"
 *          scope="request"
 *          input="/test.jsp"
 *      parameter="action"/&gt;
 * </pre> <p>
 *
 *  which will use the value of the request parameter named "action" to locate
 *  the corresponding key in ApplicationResources. For example, you might have
 *  the following ApplicationResources.properties:</p> <pre>
 *    button.add=Add Record
 *    button.delete=Delete Record
 *  </pre><p>
 *
 *  And your JSP would have the following format for submit buttons:</p> <pre>
 *   &lt;html:form action="/test"&gt;
 *    &lt;html:submit property="action"&gt;
 *      &lt;bean:message key="button.add"/&gt;
 *    &lt;/html:submit&gt;
 *    &lt;html:submit property="action"&gt;
 *      &lt;bean:message key="button.delete"/&gt;
 *    &lt;/html:submit&gt;
 *  &lt;/html:form&gt;
 *  </pre> <p>
 *
 *  Your subclass must implement both getKeyMethodMap and the
 *  methods defined in the map. An example of such implementations are:</p>
 * <pre>
 *  protected Map getKeyMethodMap() {
 *      Map map = new HashMap();
 *      map.put("button.add", "add");
 *      map.put("button.delete", "delete");
 *      return map;
 *  }
 *
 *  public ActionForward add(ActionMapping mapping,
 *          ActionForm form,
 *          HttpServletRequest request,
 *          HttpServletResponse response)
 *          throws IOException, ServletException {
 *      // do add
 *      return mapping.findForward("success");
 *  }
 *
 *  public ActionForward delete(ActionMapping mapping,
 *          ActionForm form,
 *          HttpServletRequest request,
 *          HttpServletResponse response)
 *          throws IOException, ServletException {
 *      // do delete
 *      return mapping.findForward("success");
 *  }
 *  <p>
 *
 *  <strong>Notes</strong> - If duplicate values exist for the keys returned by
 *  getKeys, only the first one found will be returned. If no corresponding key
 *  is found then an exception will be thrown.
 *
 * @author Erik Hatcher
 * @author Scott Carlson
 * @author David Graham
 */
public abstract class LookupDispatchAction extends DispatchAction {

    /**
     * Reverse lookup map from resource value to resource key.
     */
    protected Map localeMap = new HashMap();

    /**
     * Resource key to method name lookup.
     */
    protected Map keyMethodMap = null;

    // ---------------------------------------------------------- Public Methods

    /**
     *  Process the specified HTTP request, and create the corresponding HTTP
     *  response (or forward to another web component that will create it).
     *  Return an <code>ActionForward</code> instance describing where and how
     *  control should be forwarded, or <code>null</code> if the response has
     *  already been completed.
     *
     * @param mapping The ActionMapping used to select this instance
     * @param request The HTTP request we are processing
     * @param response The HTTP response we are creating
     * @param form The optional ActionForm bean for this request (if any)
     * @return Describes where and how control should be forwarded.
     * @exception Exception if an error occurs
     */
    public ActionForward execute(
        ActionMapping mapping,
        ActionForm form,
        HttpServletRequest request,
        HttpServletResponse response)
        throws Exception {

        // Identify the request parameter containing the method name
        String parameter = mapping.getParameter();
        if (parameter == null) {
            String message = messages.getMessage("dispatch.handler", mapping.getPath());
            throw new ServletException(message);
        }

        // Identify the string to lookup
        String name = request.getParameter(parameter);
        if (name == null) {
            String message =
                messages.getMessage("dispatch.parameter", mapping.getPath(), parameter);
            throw new ServletException(message);
        }

        // Based on this request's Locale get the lookupMap
        Map lookupMap = null;
        Locale userLocale = getLocale(request);
        boolean newLookupMap = false;
        synchronized (localeMap) {
            lookupMap = (Map) this.localeMap.get(userLocale);
            if (lookupMap == null) {
                newLookupMap = true;
                lookupMap = new HashMap();
                this.localeMap.put(userLocale, lookupMap);
            }
        }
        
        synchronized (lookupMap) {
            if (newLookupMap) {
                /*
                 * This is the first time this Locale is used so build the reverse lookup Map.
                 * Search for message keys in all configured MessageResources for
                 * the current module.
                 */
                this.keyMethodMap = this.getKeyMethodMap();
                
                ModuleConfig moduleConfig = (ModuleConfig) request.getAttribute(Globals.MODULE_KEY);
                MessageResourcesConfig[] mrc = moduleConfig.findMessageResourcesConfigs();
                
                // Look through all module's MessageResources
                for (int i = 0; i < mrc.length; i++) {
                    MessageResources resources =
                        this.getResources(request, mrc[i].getKey());

                    // Look for key in MessageResources
                    Iterator iter = this.keyMethodMap.keySet().iterator();
                    while (iter.hasNext()) {
                        String key = (String) iter.next();
                        String text = resources.getMessage(userLocale, key);
                        
                        // Found key and haven't added to Map yet, so add the text
                        if ((text != null) && !lookupMap.containsKey(text)) {
                            lookupMap.put(text, key);
                        }
                    }
                }
            }
        }

        // Find the key
        String key = (String) lookupMap.get(name);

        String methodName = (String) keyMethodMap.get(key);

        return dispatchMethod(mapping, form, request, response, methodName);
    }

    /**
     * Provides the mapping from resource key to method name.
     *
     * @return Resource key / method name map.
     */
    protected abstract Map getKeyMethodMap();

}