Package org.apache.commons.discovery.resource.classes

Source Code of org.apache.commons.discovery.resource.classes.DiscoverClasses

/*
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* The Apache Software License, Version 1.1
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* reserved.
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* modification, are permitted provided that the following conditions
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*    notice, this list of conditions and the following disclaimer.
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*    any, must include the following acknowlegement:
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*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowlegement may appear in the software itself,
*    if and wherever such third-party acknowlegements normally appear.
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
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* individuals on behalf of the Apache Software Foundation.  For more
* information on the Apache Software Foundation, please see
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*/

package org.apache.commons.discovery.resource.classes;

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

import org.apache.commons.discovery.Resource;
import org.apache.commons.discovery.ResourceClass;
import org.apache.commons.discovery.ResourceClassDiscover;
import org.apache.commons.discovery.ResourceClassIterator;
import org.apache.commons.discovery.ResourceIterator;
import org.apache.commons.discovery.ResourceNameIterator;
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;
            }
        };
    }
}
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