001/* 002 * Copyright 2002-2017 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.annotation; 018 019import java.io.Serializable; 020 021import org.springframework.lang.Nullable; 022import org.springframework.util.Assert; 023 024/** 025 * Decorator to cause a {@link MetadataAwareAspectInstanceFactory} to instantiate only once. 026 * 027 * @author Rod Johnson 028 * @author Juergen Hoeller 029 * @since 2.0 030 */ 031@SuppressWarnings("serial") 032public class LazySingletonAspectInstanceFactoryDecorator implements MetadataAwareAspectInstanceFactory, Serializable { 033 034 private final MetadataAwareAspectInstanceFactory maaif; 035 036 @Nullable 037 private volatile Object materialized; 038 039 040 /** 041 * Create a new lazily initializing decorator for the given AspectInstanceFactory. 042 * @param maaif the MetadataAwareAspectInstanceFactory to decorate 043 */ 044 public LazySingletonAspectInstanceFactoryDecorator(MetadataAwareAspectInstanceFactory maaif) { 045 Assert.notNull(maaif, "AspectInstanceFactory must not be null"); 046 this.maaif = maaif; 047 } 048 049 050 @Override 051 public Object getAspectInstance() { 052 Object aspectInstance = this.materialized; 053 if (aspectInstance == null) { 054 Object mutex = this.maaif.getAspectCreationMutex(); 055 if (mutex == null) { 056 aspectInstance = this.maaif.getAspectInstance(); 057 this.materialized = aspectInstance; 058 } 059 else { 060 synchronized (mutex) { 061 aspectInstance = this.materialized; 062 if (aspectInstance == null) { 063 aspectInstance = this.maaif.getAspectInstance(); 064 this.materialized = aspectInstance; 065 } 066 } 067 } 068 } 069 return aspectInstance; 070 } 071 072 public boolean isMaterialized() { 073 return (this.materialized != null); 074 } 075 076 @Override 077 @Nullable 078 public ClassLoader getAspectClassLoader() { 079 return this.maaif.getAspectClassLoader(); 080 } 081 082 @Override 083 public AspectMetadata getAspectMetadata() { 084 return this.maaif.getAspectMetadata(); 085 } 086 087 @Override 088 @Nullable 089 public Object getAspectCreationMutex() { 090 return this.maaif.getAspectCreationMutex(); 091 } 092 093 @Override 094 public int getOrder() { 095 return this.maaif.getOrder(); 096 } 097 098 099 @Override 100 public String toString() { 101 return "LazySingletonAspectInstanceFactoryDecorator: decorating " + this.maaif; 102 } 103 104}