server/src/main/java/org/apache/asyncweb/server/resolver/CompositeResolver.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.asyncweb.server.resolver;

import java.util.ArrayList;
import java.util.List;

import org.apache.asyncweb.common.HttpRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A <code>ServiceResolver</code> which applies a list of child
 * resolvers in turn until a match is made or all children have
 * been tried
 *
 * @author irvingd
 *
 */
public class CompositeResolver implements ServiceResolver {

    private static final Logger LOG = LoggerFactory
            .getLogger(CompositeResolver.class);

    private List<ServiceResolver> resolvers = new ArrayList<ServiceResolver>();

    /**
     * Requests all child resolvers to resolve the request until either
     * a resolution is found, or all child resolvers have been tried.
     *
     * @param  request  The request to resolve
     * @return The service name, or <code>null</code> if no resolution could
     *         be found
     */
    public String resolveService(HttpRequest request) {
        for (int i = 0, size = resolvers.size(); i < size; ++i) {
            ServiceResolver resolver = resolvers.get(i);
            String name = resolver.resolveService(request);
            if (name != null) {
                return name;
            }
        }
        return null;
    }

    /**
     * Adds a resolver. Resolvers are applied in the order they are
     * added
     *
     * @param resolver  The resolver
     */
    public void addResolver(ServiceResolver resolver) {
        resolvers.add(resolver);
        LOG.info("Added resolver: " + resolver.getClass());
    }

    /**
     * Sets the resolvers employed by this <code>CompositeResolver</code>
     *
     * @param resolvers  The resolvers
     */
    public void setResolvers(List<ServiceResolver> resolvers) {
        this.resolvers.clear();
        // Find bad types early
        for (ServiceResolver resolver : resolvers) {
         addResolver(resolver);
      }
    }

}