org.apache.commons.discovery.resource.classes.DiscoverClasses.java Source code

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Here is the source code for org.apache.commons.discovery.resource.classes.DiscoverClasses.java

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/*
 * 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.commons.discovery.resource.classes;

import java.net.URL;
import java.util.Vector;

import org.apache.commons.discovery.ResourceClass;
import org.apache.commons.discovery.ResourceClassDiscover;
import org.apache.commons.discovery.ResourceClassIterator;
import org.apache.commons.discovery.log.DiscoveryLogFactory;
import org.apache.commons.discovery.resource.ClassLoaders;
import org.apache.commons.logging.Log;

/**
 * The findResources() method will check every loader.
 *
 * @author Richard A. Sitze
 * @author Craig R. McClanahan
 * @author Costin Manolache
 * @author James Strachan
 */
public class DiscoverClasses extends ResourceClassDiscoverImpl implements ResourceClassDiscover {
    private static Log log = DiscoveryLogFactory.newLog(DiscoverClasses.class);

    public static void setLog(Log _log) {
        log = _log;
    }

    /** Construct a new resource discoverer
     */
    public DiscoverClasses() {
        super();
    }

    /** Construct a new resource discoverer
     */
    public DiscoverClasses(ClassLoaders classLoaders) {
        super(classLoaders);
    }

    public ResourceClassIterator findResourceClasses(final String className) {
        final String resourceName = className.replace('.', '/') + ".class";

        if (log.isDebugEnabled())
            log.debug("find: className='" + className + "'");

        return new ResourceClassIterator() {
            private Vector history = new Vector();
            private int idx = 0;
            private ResourceClass resource = null;

            public boolean hasNext() {
                if (resource == null) {
                    resource = getNextClass();
                }
                return resource != null;
            }

            public ResourceClass nextResourceClass() {
                ResourceClass element = resource;
                resource = null;
                return element;
            }

            private ResourceClass getNextClass() {
                while (idx < getClassLoaders().size()) {
                    ClassLoader loader = getClassLoaders().get(idx++);
                    URL url = loader.getResource(resourceName);
                    if (url != null) {
                        if (!history.contains(url)) {
                            history.addElement(url);

                            if (log.isDebugEnabled())
                                log.debug("getNextClass: next URL='" + url + "'");

                            return new ResourceClass(className, url, loader);
                        }
                        if (log.isDebugEnabled())
                            log.debug("getNextClass: duplicate URL='" + url + "'");
                    } else {
                        if (log.isDebugEnabled())
                            log.debug("getNextClass: loader " + loader + ": '" + resourceName + "' not found");
                    }
                }
                return null;
            }
        };
    }
}