001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 */
019
020package org.apache.isis.core.commons.resource;
021
022import java.io.InputStream;
023import java.io.OutputStream;
024import java.io.SequenceInputStream;
025import java.util.ArrayList;
026import java.util.List;
027import java.util.Vector;
028
029import org.slf4j.Logger;
030import org.slf4j.LoggerFactory;
031
032public class ResourceStreamSourceComposite extends ResourceStreamSourceAbstract {
033
034    private static Logger LOG = LoggerFactory.getLogger(ResourceStreamSourceComposite.class);
035
036    private final List<ResourceStreamSource> resourceStreamSources = new ArrayList<ResourceStreamSource>();
037
038    public ResourceStreamSourceComposite(final ResourceStreamSource... resourceStreamSources) {
039        for (final ResourceStreamSource rss : resourceStreamSources) {
040            addResourceStreamSource(rss);
041        }
042    }
043
044    public void addResourceStreamSource(final ResourceStreamSource rss) {
045        this.resourceStreamSources.add(rss);
046    }
047
048    @Override
049    protected InputStream doReadResource(final String resourcePath) {
050        Vector<InputStream> compositionStreams = new Vector<InputStream>();
051        for (final ResourceStreamSource rss : resourceStreamSources) {
052            final InputStream resourceStream = rss.readResource(resourcePath);
053            if (resourceStream != null) {
054                compositionStreams.add(resourceStream);
055            }
056        }
057        if (!compositionStreams.isEmpty()) {
058            return new SequenceInputStream(compositionStreams.elements());
059        }
060        if (LOG.isDebugEnabled()) {
061            LOG.debug("could not load resource path '" + resourcePath + "' from " + getName());
062        }
063        return null;
064    }
065
066    @Override
067    public OutputStream writeResource(final String resourcePath) {
068        return null; // No support for writing resources
069    }
070
071    @Override
072    public String getName() {
073        return "composite [" + resourceStreamNames() + "]";
074    }
075
076    private String resourceStreamNames() {
077        final StringBuilder buf = new StringBuilder();
078        boolean first = true;
079        for (final ResourceStreamSource rss : resourceStreamSources) {
080            if (first) {
081                first = false;
082            } else {
083                buf.append(", ");
084            }
085            buf.append(rss.getName());
086        }
087        return buf.toString();
088    }
089
090}