org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor.java Source code

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Here is the source code for org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor.java

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/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.config;

import java.lang.reflect.Constructor;

import org.springframework.beans.BeansException;
import org.springframework.lang.Nullable;

/**
 * Extension of the {@link InstantiationAwareBeanPostProcessor} interface,
 * adding a callback for predicting the eventual type of a processed bean.
 *
 * <p><b>NOTE:</b> This interface is a special purpose interface, mainly for
 * internal use within the framework. In general, application-provided
 * post-processors should simply implement the plain {@link BeanPostProcessor}
 * interface or derive from the {@link InstantiationAwareBeanPostProcessorAdapter}
 * class. New methods might be added to this interface even in point releases.
 *
 * @author Juergen Hoeller
 * @since 2.0.3
 * @see InstantiationAwareBeanPostProcessorAdapter
 */
public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor {

    /**
     * Predict the type of the bean to be eventually returned from this
     * processor's {@link #postProcessBeforeInstantiation} callback.
     * <p>The default implementation returns {@code null}.
     * @param beanClass the raw class of the bean
     * @param beanName the name of the bean
     * @return the type of the bean, or {@code null} if not predictable
     * @throws org.springframework.beans.BeansException in case of errors
     */
    @Nullable
    default Class<?> predictBeanType(Class<?> beanClass, String beanName) throws BeansException {
        return null;
    }

    /**
     * Determine the candidate constructors to use for the given bean.
     * <p>The default implementation returns {@code null}.
     * @param beanClass the raw class of the bean (never {@code null})
     * @param beanName the name of the bean
     * @return the candidate constructors, or {@code null} if none specified
     * @throws org.springframework.beans.BeansException in case of errors
     */
    @Nullable
    default Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName)
            throws BeansException {

        return null;
    }

    /**
     * Obtain a reference for early access to the specified bean,
     * typically for the purpose of resolving a circular reference.
     * <p>This callback gives post-processors a chance to expose a wrapper
     * early - that is, before the target bean instance is fully initialized.
     * The exposed object should be equivalent to the what
     * {@link #postProcessBeforeInitialization} / {@link #postProcessAfterInitialization}
     * would expose otherwise. Note that the object returned by this method will
     * be used as bean reference unless the post-processor returns a different
     * wrapper from said post-process callbacks. In other words: Those post-process
     * callbacks may either eventually expose the same reference or alternatively
     * return the raw bean instance from those subsequent callbacks (if the wrapper
     * for the affected bean has been built for a call to this method already,
     * it will be exposes as final bean reference by default).
     * <p>The default implementation returns the given {@code bean} as-is.
     * @param bean the raw bean instance
     * @param beanName the name of the bean
     * @return the object to expose as bean reference
     * (typically with the passed-in bean instance as default)
     * @throws org.springframework.beans.BeansException in case of errors
     */
    default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
        return bean;
    }

}