InstantiationAwareBeanPostProcessor


1   /*
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4    * Licensed under the Apache License, Version 2.0 (the "License");
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8    *      http://www.apache.org/licenses/LICENSE-2.0
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10   * Unless required by applicable law or agreed to in writing, software
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13   * See the License for the specific language governing permissions and
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15   */
16  
17  package org.springframework.beans.factory.config;
18  
19  import java.beans.PropertyDescriptor  ;
20  
21  import org.springframework.beans.BeansException;
22  import org.springframework.beans.PropertyValues;
23  
24  /**
25   * Subinterface of {@link BeanPostProcessor} that adds a before-instantiation callback,
26   * and a callback after instantiation but before explicit properties are set or
27   * autowiring occurs.
28   *
29   * <p>Typically used to suppress default instantiation for specific target beans,
30   * for example to create proxies with special TargetSources (pooling targets,
31   * lazily initializing targets, etc), or to implement additional injection strategies
32   * such as field injection.
33   *
34   * <p><b>NOTE:</b> This interface is a special purpose interface, mainly for
35   * internal use within the framework. It is recommended to implement the plain
36   * {@link BeanPostProcessor} interface as far as possible, or to derive from
37   * {@link InstantiationAwareBeanPostProcessorAdapter} in order to be shielded
38   * from extensions to this interface.
39   *
40   * @author Juergen Hoeller
41   * @author Rod Johnson
42   * @since 1.2
43   * @see org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#setCustomTargetSourceCreators
44   * @see org.springframework.aop.framework.autoproxy.target.LazyInitTargetSourceCreator
45   */
46  public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {
47  
48      /**
49       * Apply this BeanPostProcessor <i>before the target bean gets instantiated</i>.
50       * The returned bean object may be a proxy to use instead of the target bean,
51       * effectively suppressing default instantiation of the target bean.
52       * <p>If a non-null object is returned by this method, the bean creation process
53       * will be short-circuited. The only further processing applied is the
54       * {@link #postProcessAfterInitialization} callback from the configured
55       * {@link BeanPostProcessor BeanPostProcessors}.
56       * <p>This callback will only be applied to bean definitions with a bean class.
57       * In particular, it will not be applied to beans with a "factory-method".
58       * <p>Post-processors may implement the extended
59       * {@link SmartInstantiationAwareBeanPostProcessor} interface in order
60       * to predict the type of the bean object that they are going to return here.
61       * @param beanClass the class of the bean to be instantiated
62       * @param beanName the name of the bean
63       * @return the bean object to expose instead of a default instance of the target bean,
64       * or <code>null</code> to proceed with default instantiation
65       * @throws org.springframework.beans.BeansException in case of errors
66       * @see org.springframework.beans.factory.support.AbstractBeanDefinition#hasBeanClass
67       * @see org.springframework.beans.factory.support.AbstractBeanDefinition#getFactoryMethodName
68       */
69      Object   postProcessBeforeInstantiation(Class   beanClass, String   beanName) throws BeansException;
70  
71      /**
72       * Perform operations after the bean has been instantiated, via a constructor or factory method,
73       * but before Spring property population (from explicit properties or autowiring) occurs.
74       * @param bean the bean instance created, but whose properties have not yet been set
75       * @param beanName the name of the bean
76       * @return <code>true</code> if properties should be set on the bean; <code>false</code>
77       * if property population should be skipped. Normal implementations should return <code>true</code>.
78       * Returning <code>false</code> will also prevent any subsequent InstantiationAwareBeanPostProcessor
79       * instances being invoked on this bean instance.
80       * @throws org.springframework.beans.BeansException in case of errors
81       */
82      boolean postProcessAfterInstantiation(Object   bean, String   beanName) throws BeansException;
83  
84      /**
85       * Post-process the given property values before the factory applies them
86       * to the given bean. Allows for checking whether all dependencies have been
87       * satisfied, for example based on a "Required" annotation on bean property setters.
88       * <p>Also allows for replacing the property values to apply, typically through
89       * creating a new MutablePropertyValues instance based on the original PropertyValues,
90       * adding or removing specific values.
91       * @param pvs the property values that the factory is about to apply (never <code>null</code>)
92       * @param pds the relevant property descriptors for the target bean (with ignored
93       * dependency types - which the factory handles specifically - already filtered out)
94       * @param bean the bean instance created, but whose properties have not yet been set
95       * @param beanName the name of the bean
96       * @return the actual property values to apply to to the given bean
97       * (can be the passed-in PropertyValues instance), or <code>null</code>
98       * to skip property population
99       * @throws org.springframework.beans.BeansException in case of errors
100      * @see org.springframework.beans.MutablePropertyValues
101      */
102     PropertyValues postProcessPropertyValues(
103             PropertyValues pvs, PropertyDescriptor  [] pds, Object   bean, String   beanName)
104             throws BeansException;
105 
106 }
107
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