001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.spi;
018
019import java.lang.annotation.Annotation;
020import java.util.Set;
021
022import org.apache.camel.StaticService;
023
024/**
025 * A resolver that can find resources based on package scanning.
026 */
027public interface PackageScanClassResolver extends StaticService {
028
029    /**
030     * Gets the ClassLoader instances that should be used when scanning for classes.
031     * <p/>
032     * This implementation will return a new unmodifiable set containing the classloaders.
033     * Use the {@link #addClassLoader(ClassLoader)} method if you want to add new classloaders
034     * to the class loaders list.
035     *
036     * @return the class loaders to use
037     */
038    Set<ClassLoader> getClassLoaders();
039
040    /**
041     * Adds the class loader to the existing loaders
042     *
043     * @param classLoader the loader to add
044     */
045    void addClassLoader(ClassLoader classLoader);
046
047    /**
048     * Attempts to discover classes that are annotated with to the annotation.
049     *
050     * @param annotation   the annotation that should be present on matching classes
051     * @param packageNames one or more package names to scan (including subpackages) for classes
052     * @return the classes found, returns an empty set if none found
053     */
054    Set<Class<?>> findAnnotated(Class<? extends Annotation> annotation, String... packageNames);
055
056    /**
057     * Attempts to discover classes that are annotated with to the annotation.
058     *
059     * @param annotations   the annotations that should be present (any of them) on matching classes
060     * @param packageNames one or more package names to scan (including subpackages) for classes
061     * @return the classes found, returns an empty set if none found
062     */
063    Set<Class<?>> findAnnotated(Set<Class<? extends Annotation>> annotations, String... packageNames);
064
065    /**
066     * Attempts to discover classes that are assignable to the type provided. In
067     * the case that an interface is provided this method will collect
068     * implementations. In the case of a non-interface class, subclasses will be
069     * collected.
070     *
071     * @param parent       the class of interface to find subclasses or implementations of
072     * @param packageNames one or more package names to scan (including subpackages) for classes
073     * @return the classes found, returns an empty set if none found
074     */
075    Set<Class<?>> findImplementations(Class<?> parent, String... packageNames);
076
077    /**
078     * Attempts to discover classes filter by the provided filter
079     *
080     * @param filter  filter to filter desired classes.
081     * @param packageNames one or more package names to scan (including subpackages) for classes
082     * @return the classes found, returns an empty set if none found
083     */
084    Set<Class<?>> findByFilter(PackageScanFilter filter, String... packageNames);
085    
086    /**
087     * Add a filter that will be applied to all scan operations
088     * 
089     * @param filter filter to filter desired classes in all scan operations
090     */
091    void addFilter(PackageScanFilter filter);
092
093    /**
094     * Removes the filter
095     *
096     * @param filter filter to filter desired classes in all scan operations
097     */
098    void removeFilter(PackageScanFilter filter);
099}