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.springframework.beans.factory.config; 018 019import java.lang.reflect.Constructor; 020 021import org.springframework.beans.BeansException; 022import org.springframework.lang.Nullable; 023 024/** 025 * Extension of the {@link InstantiationAwareBeanPostProcessor} interface, 026 * adding a callback for predicting the eventual type of a processed bean. 027 * 028 * <p><b>NOTE:</b> This interface is a special purpose interface, mainly for 029 * internal use within the framework. In general, application-provided 030 * post-processors should simply implement the plain {@link BeanPostProcessor} 031 * interface or derive from the {@link InstantiationAwareBeanPostProcessorAdapter} 032 * class. New methods might be added to this interface even in point releases. 033 * 034 * @author Juergen Hoeller 035 * @since 2.0.3 036 * @see InstantiationAwareBeanPostProcessorAdapter 037 */ 038public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor { 039 040 /** 041 * Predict the type of the bean to be eventually returned from this 042 * processor's {@link #postProcessBeforeInstantiation} callback. 043 * <p>The default implementation returns {@code null}. 044 * @param beanClass the raw class of the bean 045 * @param beanName the name of the bean 046 * @return the type of the bean, or {@code null} if not predictable 047 * @throws org.springframework.beans.BeansException in case of errors 048 */ 049 @Nullable 050 default Class<?> predictBeanType(Class<?> beanClass, String beanName) throws BeansException { 051 return null; 052 } 053 054 /** 055 * Determine the candidate constructors to use for the given bean. 056 * <p>The default implementation returns {@code null}. 057 * @param beanClass the raw class of the bean (never {@code null}) 058 * @param beanName the name of the bean 059 * @return the candidate constructors, or {@code null} if none specified 060 * @throws org.springframework.beans.BeansException in case of errors 061 */ 062 @Nullable 063 default Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) 064 throws BeansException { 065 066 return null; 067 } 068 069 /** 070 * Obtain a reference for early access to the specified bean, 071 * typically for the purpose of resolving a circular reference. 072 * <p>This callback gives post-processors a chance to expose a wrapper 073 * early - that is, before the target bean instance is fully initialized. 074 * The exposed object should be equivalent to the what 075 * {@link #postProcessBeforeInitialization} / {@link #postProcessAfterInitialization} 076 * would expose otherwise. Note that the object returned by this method will 077 * be used as bean reference unless the post-processor returns a different 078 * wrapper from said post-process callbacks. In other words: Those post-process 079 * callbacks may either eventually expose the same reference or alternatively 080 * return the raw bean instance from those subsequent callbacks (if the wrapper 081 * for the affected bean has been built for a call to this method already, 082 * it will be exposes as final bean reference by default). 083 * <p>The default implementation returns the given {@code bean} as-is. 084 * @param bean the raw bean instance 085 * @param beanName the name of the bean 086 * @return the object to expose as bean reference 087 * (typically with the passed-in bean instance as default) 088 * @throws org.springframework.beans.BeansException in case of errors 089 */ 090 default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException { 091 return bean; 092 } 093 094}