/*
* $Id: Action.java 471754 2006-11-06 14:55:09Z husted $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts.action;
import org.apache.struts.Globals;
import org.apache.struts.config.ModuleConfig;
import org.apache.struts.util.MessageResources;
import org.apache.struts.util.ModuleUtils;
import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.TokenProcessor;
import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.Locale;
/**
* <p>An <strong>Action</strong> is an adapter between the contents of an
* incoming HTTP request and the corresponding business logic that should be
* executed to process this request. The controller (RequestProcessor) will
* select an appropriate Action for each request, create an instance (if
* necessary), and call the <code>execute</code> method.</p>
*
* <p>Actions must be programmed in a thread-safe manner, because the
* controller will share the same instance for multiple simultaneous requests.
* This means you should design with the following items in mind: </p>
*
* <ul>
*
* <li>Instance and static variables MUST NOT be used to store information
* related to the state of a particular request. They MAY be used to share
* global resources across requests for the same action.</li>
*
* <li>Access to other resources (JavaBeans, session variables, etc.) MUST be
* synchronized if those resources require protection. (Generally, however,
* resource classes should be designed to provide their own protection where
* necessary.</li>
*
* </ul>
*
* <p>When an <code>Action</code> instance is first created, the controller
* will call <code>setServlet</code> with a non-null argument to identify the
* servlet instance to which this Action is attached. When the servlet is to
* be shut down (or restarted), the <code>setServlet</code> method will be
* called with a <code>null</code> argument, which can be used to clean up any
* allocated resources in use by this Action.</p>
*
* @version $Rev: 471754 $ $Date: 2005-08-26 21:58:39 -0400 (Fri, 26 Aug 2005)
* $
*/
public class Action {
/**
* <p>An instance of <code>TokenProcessor</code> to use for token
* functionality.</p>
*/
private static TokenProcessor token = TokenProcessor.getInstance();
// NOTE: We can make the tken variable protected and remove Action's
// token methods or leave it private and allow the token methods to
// delegate their calls.
// ----------------------------------------------------- Instance Variables
/**
* <p>The servlet to which we are attached.</p>
*/
protected transient ActionServlet servlet = null;
// ------------------------------------------------------------- Properties
/**
* <p>Return the servlet instance to which we are attached.</p>
*
* @return The servlet instance to which we are attached.
*/
public ActionServlet getServlet() {
return (this.servlet);
}
/**
* <p>Set the servlet instance to which we are attached (if
* <code>servlet</code> is non-null), or release any allocated resources
* (if <code>servlet</code> is null).</p>
*
* @param servlet The new controller servlet, if any
*/
public void setServlet(ActionServlet servlet) {
this.servlet = servlet;
// :FIXME: Is this suppose to release resources?
}
// --------------------------------------------------------- Public Methods
/**
* <p>Process the specified non-HTTP request, and create the corresponding
* non-HTTP response (or forward to another web component that will create
* it), with provision for handling exceptions thrown by the business
* logic. Return an {@link ActionForward} instance describing where and
* how control should be forwarded, or <code>null</code> if the response
* has already been completed.</p>
*
* <p>The default implementation attempts to forward to the HTTP version
* of this method.</p>
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The non-HTTP request we are processing
* @param response The non-HTTP response we are creating
* @return The forward to which control should be transferred, or
* <code>null</code> if the response has been completed.
* @throws Exception if the application business logic throws an
* exception.
* @since Struts 1.1
*/
public ActionForward execute(ActionMapping mapping, ActionForm form,
ServletRequest request, ServletResponse response)
throws Exception {
try {
return execute(mapping, form, (HttpServletRequest) request,
(HttpServletResponse) response);
} catch (ClassCastException e) {
return null;
}
}
/**
* <p>Process the specified HTTP request, and create the corresponding
* HTTP response (or forward to another web component that will create
* it), with provision for handling exceptions thrown by the business
* logic. Return an {@link ActionForward} instance describing where and
* how control should be forwarded, or <code>null</code> if the response
* has already been completed.</p>
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The HTTP request we are processing
* @param response The HTTP response we are creating
* @return The forward to which control should be transferred, or
* <code>null</code> if the response has been completed.
* @throws Exception if the application business logic throws an
* exception
* @since Struts 1.1
*/
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
return null;
}
// ---------------------------------------------------- Protected Methods
/**
* Adds the specified messages keys into the appropriate request attribute
* for use by the <html:messages> tag (if messages="true" is set),
* if any messages are required. Initialize the attribute if it has not
* already been. Otherwise, ensure that the request attribute is not set.
*
* @param request The servlet request we are processing
* @param messages Messages object
* @since Struts 1.2.1
*/
protected void addMessages(HttpServletRequest request,
ActionMessages messages) {
if (messages == null) {
// bad programmer! *slap*
return;
}
// get any existing messages from the request, or make a new one
ActionMessages requestMessages =
(ActionMessages) request.getAttribute(Globals.MESSAGE_KEY);
if (requestMessages == null) {
requestMessages = new ActionMessages();
}
// add incoming messages
requestMessages.add(messages);
// if still empty, just wipe it out from the request
if (requestMessages.isEmpty()) {
request.removeAttribute(Globals.MESSAGE_KEY);
return;
}
// Save the messages
request.setAttribute(Globals.MESSAGE_KEY, requestMessages);
}
/**
* Adds the specified errors keys into the appropriate request attribute
* for use by the <html:errors> tag, if any messages are required.
* Initialize the attribute if it has not already been. Otherwise, ensure
* that the request attribute is not set.
*
* @param request The servlet request we are processing
* @param errors Errors object
* @since Struts 1.2.1
*/
protected void addErrors(HttpServletRequest request, ActionMessages errors) {
if (errors == null) {
// bad programmer! *slap*
return;
}
// get any existing errors from the request, or make a new one
ActionMessages requestErrors =
(ActionMessages) request.getAttribute(Globals.ERROR_KEY);
if (requestErrors == null) {
requestErrors = new ActionMessages();
}
// add incoming errors
requestErrors.add(errors);
// if still empty, just wipe it out from the request
if (requestErrors.isEmpty()) {
request.removeAttribute(Globals.ERROR_KEY);
return;
}
// Save the errors
request.setAttribute(Globals.ERROR_KEY, requestErrors);
}
/**
* <p>Generate a new transaction token, to be used for enforcing a single
* request for a particular transaction.</p>
*
* @param request The request we are processing
* @return The new transaction token.
*/
protected String generateToken(HttpServletRequest request) {
return token.generateToken(request);
}
/**
* Retrieves any existing errors placed in the request by previous
* actions. This method could be called instead of creating a <code>new
* ActionMessages()</code> at the beginning of an <code>Action</code>.
* This will prevent saveErrors() from wiping out any existing Errors
*
* @param request The servlet request we are processing
* @return the Errors that already exist in the request, or a new
* ActionMessages object if empty.
* @since Struts 1.2.1
*/
protected ActionMessages getErrors(HttpServletRequest request) {
ActionMessages errors =
(ActionMessages) request.getAttribute(Globals.ERROR_KEY);
if (errors == null) {
errors = new ActionMessages();
}
return errors;
}
/**
* <p>Return the user's currently selected Locale.</p>
*
* @param request The request we are processing
* @return The user's currently selected Locale.
*/
protected Locale getLocale(HttpServletRequest request) {
return RequestUtils.getUserLocale(request, null);
}
/**
* <p> Retrieves any existing messages placed in the request by previous
* actions. This method could be called instead of creating a <code>new
* ActionMessages()</code> at the beginning of an <code>Action</code> This
* will prevent saveMessages() from wiping out any existing Messages </p>
*
* @param request The servlet request we are processing
* @return the Messages that already exist in the request, or a new
* ActionMessages object if empty.
* @since Struts 1.2.1
*/
protected ActionMessages getMessages(HttpServletRequest request) {
ActionMessages messages =
(ActionMessages) request.getAttribute(Globals.MESSAGE_KEY);
if (messages == null) {
messages = new ActionMessages();
}
return messages;
}
/**
* <p>Return the default message resources for the current module.</p>
*
* @param request The servlet request we are processing
* @return The default message resources for the current module.
* @since Struts 1.1
*/
protected MessageResources getResources(HttpServletRequest request) {
return ((MessageResources) request.getAttribute(Globals.MESSAGES_KEY));
}
/**
* <p>Return the specified message resources for the current module.</p>
*
* @param request The servlet request we are processing
* @param key The key specified in the message-resources element for
* the requested bundle.
* @return The specified message resource for the current module.
* @since Struts 1.1
*/
protected MessageResources getResources(HttpServletRequest request,
String key) {
// Identify the current module
ServletContext context = getServlet().getServletContext();
ModuleConfig moduleConfig =
ModuleUtils.getInstance().getModuleConfig(request, context);
// Return the requested message resources instance
return (MessageResources) context.getAttribute(key
+ moduleConfig.getPrefix());
}
/**
* <p>Returns <code>true</code> if the current form's cancel button was
* pressed. This method will check if the <code>Globals.CANCEL_KEY</code>
* request attribute has been set, which normally occurs if the cancel
* button generated by <strong>CancelTag</strong> was pressed by the user
* in the current request. If <code>true</code>, validation performed by
* an <strong>ActionForm</strong>'s <code>validate()</code> method will
* have been skipped by the controller servlet.</p>
*
* <p> Since Action 1.3.0, the mapping for a cancellable Action must also have
* the new "cancellable" property set to true. If "cancellable" is not set, and
* the magic Cancel token is found in the request, the standard Composable
* Request Processor will throw an InvalidCancelException. </p>
*
* @param request The servlet request we are processing
* @return <code>true</code> if the cancel button was pressed;
* <code>false</code> otherwise.
*/
protected boolean isCancelled(HttpServletRequest request) {
return (request.getAttribute(Globals.CANCEL_KEY) != null);
}
/**
* <p>Return <code>true</code> if there is a transaction token stored in
* the user's current session, and the value submitted as a request
* parameter with this action matches it. Returns <code>false</code> under
* any of the following circumstances:</p>
*
* <ul>
*
* <li>No session associated with this request</li>
*
* <li>No transaction token saved in the session</li>
*
* <li>No transaction token included as a request parameter</li>
*
* <li>The included transaction token value does not match the transaction
* token in the user's session</li>
*
* </ul>
*
* @param request The servlet request we are processing
* @return <code>true</code> if there is a transaction token and it is
* valid; <code>false</code> otherwise.
*/
protected boolean isTokenValid(HttpServletRequest request) {
return token.isTokenValid(request, false);
}
/**
* <p>Return <code>true</code> if there is a transaction token stored in
* the user's current session, and the value submitted as a request
* parameter with this action matches it. Returns <code>false</code> under
* any of the following circumstances:</p>
*
* <ul>
*
* <li>No session associated with this request</li> <li>No transaction
* token saved in the session</li>
*
* <li>No transaction token included as a request parameter</li>
*
* <li>The included transaction token value does not match the transaction
* token in the user's session</li>
*
* </ul>
*
* @param request The servlet request we are processing
* @param reset Should we reset the token after checking it?
* @return <code>true</code> if there is a transaction token and it is
* valid; <code>false</code> otherwise.
*/
protected boolean isTokenValid(HttpServletRequest request, boolean reset) {
return token.isTokenValid(request, reset);
}
/**
* <p>Reset the saved transaction token in the user's session. This
* indicates that transactional token checking will not be needed on the
* next request that is submitted.</p>
*
* @param request The servlet request we are processing
*/
protected void resetToken(HttpServletRequest request) {
token.resetToken(request);
}
/**
* <p>Save the specified error messages keys into the appropriate request
* attribute for use by the <html:errors> tag, if any messages are
* required. Otherwise, ensure that the request attribute is not
* created.</p>
*
* @param request The servlet request we are processing
* @param errors Error messages object
* @since Struts 1.2
*/
protected void saveErrors(HttpServletRequest request, ActionMessages errors) {
// Remove any error messages attribute if none are required
if ((errors == null) || errors.isEmpty()) {
request.removeAttribute(Globals.ERROR_KEY);
return;
}
// Save the error messages we need
request.setAttribute(Globals.ERROR_KEY, errors);
}
/**
* <p>Save the specified messages keys into the appropriate request
* attribute for use by the <html:messages> tag (if messages="true"
* is set), if any messages are required. Otherwise, ensure that the
* request attribute is not created.</p>
*
* @param request The servlet request we are processing.
* @param messages The messages to save. <code>null</code> or empty
* messages removes any existing ActionMessages in the
* request.
* @since Struts 1.1
*/
protected void saveMessages(HttpServletRequest request,
ActionMessages messages) {
// Remove any messages attribute if none are required
if ((messages == null) || messages.isEmpty()) {
request.removeAttribute(Globals.MESSAGE_KEY);
return;
}
// Save the messages we need
request.setAttribute(Globals.MESSAGE_KEY, messages);
}
/**
* <p>Save the specified messages keys into the appropriate session
* attribute for use by the <html:messages> tag (if messages="true"
* is set), if any messages are required. Otherwise, ensure that the
* session attribute is not created.</p>
*
* @param session The session to save the messages in.
* @param messages The messages to save. <code>null</code> or empty
* messages removes any existing ActionMessages in the
* session.
* @since Struts 1.2
*/
protected void saveMessages(HttpSession session, ActionMessages messages) {
// Remove any messages attribute if none are required
if ((messages == null) || messages.isEmpty()) {
session.removeAttribute(Globals.MESSAGE_KEY);
return;
}
// Save the messages we need
session.setAttribute(Globals.MESSAGE_KEY, messages);
}
/**
* <p>Save the specified error messages keys into the appropriate session
* attribute for use by the <html:messages> tag (if
* messages="false") or <html:errors>, if any error messages are
* required. Otherwise, ensure that the session attribute is empty.</p>
*
* @param session The session to save the error messages in.
* @param errors The error messages to save. <code>null</code> or empty
* messages removes any existing error ActionMessages in
* the session.
* @since Struts 1.3
*/
protected void saveErrors(HttpSession session, ActionMessages errors) {
// Remove the error attribute if none are required
if ((errors == null) || errors.isEmpty()) {
session.removeAttribute(Globals.ERROR_KEY);
return;
}
// Save the errors we need
session.setAttribute(Globals.ERROR_KEY, errors);
}
/**
* <p>Save a new transaction token in the user's current session, creating
* a new session if necessary.</p>
*
* @param request The servlet request we are processing
*/
protected void saveToken(HttpServletRequest request) {
token.saveToken(request);
}
/**
* <p>Set the user's currently selected <code>Locale</code> into their
* <code>HttpSession</code>.</p>
*
* @param request The request we are processing
* @param locale The user's selected Locale to be set, or null to select
* the server's default Locale
*/
protected void setLocale(HttpServletRequest request, Locale locale) {
HttpSession session = request.getSession();
if (locale == null) {
locale = Locale.getDefault();
}
session.setAttribute(Globals.LOCALE_KEY, locale);
}
}