org.springframework.osgi.context.support.ChainedEntityResolver.java Source code

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Here is the source code for org.springframework.osgi.context.support.ChainedEntityResolver.java

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/*
 * Copyright 2006-2009 the original author or authors.
 * 
 * Licensed 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.springframework.osgi.context.support;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.Assert;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Delegated XML entity resolver.
 * 
 * @author Costin Leau
 * 
 */
class ChainedEntityResolver implements EntityResolver {

    /** logger */
    private static final Log log = LogFactory.getLog(ChainedEntityResolver.class);

    private final Map<EntityResolver, String> resolvers = new LinkedHashMap<EntityResolver, String>(2);

    public void addEntityResolver(EntityResolver resolver, String resolverToString) {
        Assert.notNull(resolver);
        resolvers.put(resolver, resolverToString);
    }

    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
        boolean trace = log.isTraceEnabled();

        for (Map.Entry<EntityResolver, String> entry : resolvers.entrySet()) {
            EntityResolver entityResolver = entry.getKey();
            if (trace)
                log.trace("Trying to resolve entity [" + publicId + "|" + systemId + "] through resolver "
                        + entry.getValue());
            InputSource entity = entityResolver.resolveEntity(publicId, systemId);

            String resolvedMsg = (entity != null ? "" : "not ");
            if (trace)
                log.trace("Entity [" + publicId + "|" + systemId + "] was " + resolvedMsg
                        + "resolved through entity resolver " + entry.getValue());

            if (entity != null) {
                return entity;
            }
        }
        return null;
    }
}