001/*
002 * Copyright 2006-2007 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.springframework.batch.item.support;
017
018import java.util.ArrayList;
019import java.util.Arrays;
020import java.util.List;
021
022import org.springframework.batch.item.ExecutionContext;
023import org.springframework.batch.item.ItemStream;
024import org.springframework.batch.item.ItemStreamException;
025
026/**
027 * Simple {@link ItemStream} that delegates to a list of other streams.
028 * 
029 * @author Dave Syer
030 * 
031 */
032public class CompositeItemStream implements ItemStream {
033
034        private final List<ItemStream> streams = new ArrayList<>();
035
036        /**
037         * Public setter for the {@link ItemStream}s.
038         * 
039         * @param streams array of {@link ItemStream}.
040         */
041        public void setStreams(ItemStream[] streams) {
042                this.streams.addAll(Arrays.asList(streams));
043        }
044
045        /**
046         * Register a {@link ItemStream} as one of the interesting providers under
047         * the provided key.
048         *
049         * @param stream an instance of {@link ItemStream} to be added to the list of streams.
050         */
051        public void register(ItemStream stream) {
052                synchronized (streams) {
053                        if (!streams.contains(stream)) {
054                                streams.add(stream);
055                        }
056                }
057        }
058
059        /**
060         * 
061         */
062        public CompositeItemStream() {
063                super();
064        }
065
066        /**
067         * Simple aggregate {@link ExecutionContext} provider for the contributions
068         * registered under the given key.
069         * 
070         * @see org.springframework.batch.item.ItemStream#update(ExecutionContext)
071         */
072    @Override
073        public void update(ExecutionContext executionContext) {
074                for (ItemStream itemStream : streams) {
075                        itemStream.update(executionContext);
076                }
077        }
078
079        /**
080         * Broadcast the call to close.
081
082         * @throws ItemStreamException thrown if one of the {@link ItemStream}s in
083         * the list fails to close.  This is a sequential operation so all itemStreams
084         * in the list after the one that failed to close will remain open.
085         */
086    @Override
087        public void close() throws ItemStreamException {
088                for (ItemStream itemStream : streams) {
089                        itemStream.close();
090                }
091        }
092
093        /**
094         * Broadcast the call to open.
095         *
096         * @throws ItemStreamException thrown if one of the {@link ItemStream}s in
097         * the list fails to open.  This is a sequential operation so all itemStreams
098         * in the list after the one that failed to open will not be opened.
099         */
100    @Override
101        public void open(ExecutionContext executionContext) throws ItemStreamException {
102                for (ItemStream itemStream : streams) {
103                        itemStream.open(executionContext);
104                }
105        }
106
107}