001/*
002 * Copyright 2002-2015 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.aop.aspectj;
018
019import java.io.Serializable;
020
021import org.springframework.core.Ordered;
022import org.springframework.lang.Nullable;
023import org.springframework.util.Assert;
024
025/**
026 * Implementation of {@link AspectInstanceFactory} that is backed by a
027 * specified singleton object, returning the same instance for every
028 * {@link #getAspectInstance()} call.
029 *
030 * @author Rod Johnson
031 * @author Juergen Hoeller
032 * @since 2.0
033 * @see SimpleAspectInstanceFactory
034 */
035@SuppressWarnings("serial")
036public class SingletonAspectInstanceFactory implements AspectInstanceFactory, Serializable {
037
038        private final Object aspectInstance;
039
040
041        /**
042         * Create a new SingletonAspectInstanceFactory for the given aspect instance.
043         * @param aspectInstance the singleton aspect instance
044         */
045        public SingletonAspectInstanceFactory(Object aspectInstance) {
046                Assert.notNull(aspectInstance, "Aspect instance must not be null");
047                this.aspectInstance = aspectInstance;
048        }
049
050
051        @Override
052        public final Object getAspectInstance() {
053                return this.aspectInstance;
054        }
055
056        @Override
057        @Nullable
058        public ClassLoader getAspectClassLoader() {
059                return this.aspectInstance.getClass().getClassLoader();
060        }
061
062        /**
063         * Determine the order for this factory's aspect instance,
064         * either an instance-specific order expressed through implementing
065         * the {@link org.springframework.core.Ordered} interface,
066         * or a fallback order.
067         * @see org.springframework.core.Ordered
068         * @see #getOrderForAspectClass
069         */
070        @Override
071        public int getOrder() {
072                if (this.aspectInstance instanceof Ordered) {
073                        return ((Ordered) this.aspectInstance).getOrder();
074                }
075                return getOrderForAspectClass(this.aspectInstance.getClass());
076        }
077
078        /**
079         * Determine a fallback order for the case that the aspect instance
080         * does not express an instance-specific order through implementing
081         * the {@link org.springframework.core.Ordered} interface.
082         * <p>The default implementation simply returns {@code Ordered.LOWEST_PRECEDENCE}.
083         * @param aspectClass the aspect class
084         */
085        protected int getOrderForAspectClass(Class<?> aspectClass) {
086                return Ordered.LOWEST_PRECEDENCE;
087        }
088
089}