SpringのFactoryBean(工場Bean)
org.springframe ework.beans.factory.FactoryBeanはインターフェースであり、Springでカスタムサービスを定義するためのコアインターフェースであり、彼自身はbean工場で定義されたbeanであり、同時にもう一つのSpringサービス対象工場を作るためのものである.
FactoryBean.java
package org.springframe ework.beans.factory;public インターフェース FactoryBean {
If. this method returns null the ファクトリー will consider the * FactoryBean as not フルー initialized and throw a. cores ponding * FactoryBeanNot Initialized Exception. * @return an instance 保存先 the bean (ショルダー not be
null; a null value
* will be considered as an indication of incomplete initialization)
* @throws Exception in case of creation errors
* @see FactoryBeanNotInitializedException
<fontsize=3> */
Object getObject() throws Exception;
Class getObjectType();
boolean isSingleton();
}
FactoryBean getObject 。
， BeanFactory ApplicationContext getBean() ， Bean BeanFactory， BeanFactory FactoryBean.getObject() 。
<spanlang=zh-cn> AbstractBeanFactory getObjectForSharedInstance(String,Object) 。
// Now we have the bean instance, which may be a normal bean or a FactoryBean.
// If it&aposs a FactoryBean, we use it to create a bean instance, unless the
// caller actually wants a reference to the factory.
if (beanInstance instanceof FactoryBean) {
if (!isFactoryDereference(name)) {
// Return bean instance from factory.
FactoryBean factory = (FactoryBean) beanInstance; //Cast toFactoryBean.
if (logger.isDebugEnabled()) {
logger.debug("Bean with name &apos" + beanName + "&apos is a factory bean");
}
try {
beanInstance = factory.getObject(); // Get the realObject
}
catch (Exception ex) {
throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);
}
if (beanInstance == null) {
throw new FactoryBeanNotInitializedException(
beanName, "FactoryBean returned null object: " +
"probably not fully initialized (maybe due to circular bean reference)");
}
}
else {
// The user wants the factory itself.
if (logger.isDebugEnabled()) {
logger.debug("Calling code asked for FactoryBean instance for name &apos" + beanName + "&apos");
}
}
}
Spring FactoryBean 。 FactoryBean， ，Spring 。
org.springframework.jndi JndiObjectFactoryBean：JNDI LookUp。
org.springframework.orm.hibernate3. LocalSessionFactoryBean： Hibernate SessionFactory bean。
org.springframework.aop.framework ProxyFactoryBean： AOP bean。
org.springframework.transaction.interceptor.TransactionProxyFactoryBean： ， 。
…………etc
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