001/* 002 * Copyright 2002-2016 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.aopalliance.intercept; 018 019/** 020 * Intercepts the construction of a new object. 021 * 022 * <p>The user should implement the {@link 023 * #construct(ConstructorInvocation)} method to modify the original 024 * behavior. E.g. the following class implements a singleton 025 * interceptor (allows only one unique instance for the intercepted 026 * class): 027 * 028 * <pre class=code> 029 * class DebuggingInterceptor implements ConstructorInterceptor { 030 * Object instance=null; 031 * 032 * Object construct(ConstructorInvocation i) throws Throwable { 033 * if(instance==null) { 034 * return instance=i.proceed(); 035 * } else { 036 * throw new Exception("singleton does not allow multiple instance"); 037 * } 038 * } 039 * } 040 * </pre> 041 * 042 * @author Rod Johnson 043 */ 044public interface ConstructorInterceptor extends Interceptor { 045 046 /** 047 * Implement this method to perform extra treatments before and 048 * after the construction of a new object. Polite implementations 049 * would certainly like to invoke {@link Joinpoint#proceed()}. 050 * @param invocation the construction joinpoint 051 * @return the newly created object, which is also the result of 052 * the call to {@link Joinpoint#proceed()}; might be replaced by 053 * the interceptor 054 * @throws Throwable if the interceptors or the target object 055 * throws an exception 056 */ 057 Object construct(ConstructorInvocation invocation) throws Throwable; 058 059}