/*
* Copyright 2002-2010 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
*
* http://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.io.Serializable;
import javax.inject.Provider;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.util.Assert;
/**
* A {@link org.springframework.beans.factory.FactoryBean} implementation that
* returns a value which is a JSR-330 {@link javax.inject.Provider} that in turn
* returns a bean sourced from a {@link org.springframework.beans.factory.BeanFactory}.
*
* <p>This is basically a JSR-330 compliant variant of Spring's good old
* {@link ObjectFactoryCreatingFactoryBean}. It can be used for traditional
* external dependency injection configuration that targets a property or
* constructor argument of type <code>javax.inject.Provider</code>, as an
* alternative to JSR-330's <code>@Inject</code> annotation-driven approach.
*
* @author Juergen Hoeller
* @since 3.0.2
* @see javax.inject.Provider
* @see ObjectFactoryCreatingFactoryBean
*/
public class ProviderCreatingFactoryBean extends AbstractFactoryBean<Provider> {
private String targetBeanName;
/**
* Set the name of the target bean.
* <p>The target does not <i>have</> to be a non-singleton bean, but realisticially
* always will be (because if the target bean were a singleton, then said singleton
* bean could simply be injected straight into the dependent object, thus obviating
* the need for the extra level of indirection afforded by this factory approach).
*/
public void setTargetBeanName(String targetBeanName) {
this.targetBeanName = targetBeanName;
}
@Override
public void afterPropertiesSet() throws Exception {
Assert.hasText(this.targetBeanName, "Property 'targetBeanName' is required");
super.afterPropertiesSet();
}
@Override
public Class getObjectType() {
return Provider.class;
}
@Override
protected Provider createInstance() {
return new TargetBeanProvider(getBeanFactory(), this.targetBeanName);
}
/**
* Independent inner class - for serialization purposes.
*/
private static class TargetBeanProvider implements Provider, Serializable {
private final BeanFactory beanFactory;
private final String targetBeanName;
public TargetBeanProvider(BeanFactory beanFactory, String targetBeanName) {
this.beanFactory = beanFactory;
this.targetBeanName = targetBeanName;
}
public Object get() throws BeansException {
return this.beanFactory.getBean(this.targetBeanName);
}
}
}
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