001    // Copyright 2008, 2010 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.services;
016    
017    import java.io.IOException;
018    
019    import org.apache.tapestry5.internal.InternalConstants;
020    import org.apache.tapestry5.internal.structure.Page;
021    import org.apache.tapestry5.services.Request;
022    
023    /**
024     * Alternative implementation, used when {@link org.apache.tapestry5.SymbolConstants#SUPPRESS_REDIRECT_FROM_ACTION_REQUESTS}
025     * is set to true.
026     */
027    public class ImmediateActionRenderResponseGenerator implements ActionRenderResponseGenerator
028    {
029        private final Request request;
030    
031        public ImmediateActionRenderResponseGenerator(Request request)
032        {
033            this.request = request;
034        }
035    
036        public void generateResponse(Page page) throws IOException
037        {
038            assert page != null;
039            if (request.getAttribute(InternalConstants.IMMEDIATE_RESPONSE_PAGE_ATTRIBUTE) != null) return;
040    
041            // We are somewhere in the middle of processing an action request, possibly something
042            // complicated like a form submission.  Tapestry components are not re-entrant, so we
043            // can't render the request right now, instead we record that we need to render
044            // a response as an attribute, and let a filter on the ComponentEventRequestHandler service
045            // do the work.
046    
047            request.setAttribute(InternalConstants.IMMEDIATE_RESPONSE_PAGE_ATTRIBUTE, page);
048        }
049    }