    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.TrackableComponentEventCallback;
    020    import org.apache.tapestry5.services.ComponentEventResultProcessor;
    021
    022    /**
    023     * A wrapper around {@link ComponentEventResultProcessor} that encapsulates capturing the exception.
    024     */
    025    @SuppressWarnings("unchecked")
    026    public class ComponentResultProcessorWrapper implements TrackableComponentEventCallback
    027    {
    028        private boolean aborted;
    029
    030        private IOException exception;
    031
    032        private final ComponentEventResultProcessor processor;
    033
    034        public ComponentResultProcessorWrapper(ComponentEventResultProcessor processor)
    035        {
    036            this.processor = processor;
    037        }
    038
    039        public boolean handleResult(Object result)
    040        {
    041            if (aborted)
    042                throw new IllegalStateException(
    043                        "Event callback has already received and processed a result value and can not do so again.");
    044
    045            try
    046            {
    047                processor.processResultValue(result);
    048            }
    049            catch (IOException ex)
    050            {
    051                exception = ex;
    052            }
    053
    054            aborted = true;
    055
    056            return true;
    057        }
    058
    059        /**
    060         * Returns true if {@link org.apache.tapestry5.ComponentEventCallback#handleResult(Object)} was invoked, false
    061         * otherwise.
    062         *
    063         * @return true if the event was aborted
    064         */
    065        public boolean isAborted()
    066        {
    067            return aborted;
    068        }
    069
    070        public void rethrow() throws IOException
    071        {
    072            if (exception != null)
    073                throw exception;
    074        }
    075
    076    }